diff mbox

[v6,media] vimc: Virtual Media Controller core, capture and sensor

Message ID 37dc3fa2c020c30f8ced9749f81394d585a37ec1.1473018878.git.helen.koike@collabora.com (mailing list archive)
State New, archived
Headers show

Commit Message

Helen Mae Koike Fornazier Sept. 4, 2016, 8:02 p.m. UTC
From: Helen Fornazier <helen.fornazier@gmail.com>

First version of the Virtual Media Controller.
Add a simple version of the core of the driver, the capture and
sensor nodes in the topology, generating a grey image in a hardcoded
format.

Signed-off-by: Helen Koike <helen.koike@collabora.com>

---

Patch based in media/master tree, and available here:
https://github.com/helen-fornazier/opw-staging/tree/vimc/devel/vpu

Changes since v5:
- Fix message "Entity type for entity Sensor A was not initialized!"
  by initializing the sensor entity.function after the calling
  v4l2_subded_init
- populate device_caps in vimc_cap_create instead of in
  vimc_cap_querycap
- Fix typo in vimc-core.c s/de/the

Changes since v4:
- coding style fixes
- remove BUG_ON
- change copyright to 2016
- depens on VIDEO_V4L2_SUBDEV_API instead of select
- remove assignement of V4L2_CAP_DEVICE_CAPS
- s/vimc_cap_g_fmt_vid_cap/vimc_cap_fmt_vid_cap
- fix vimc_cap_queue_setup declaration type
- remove wrong buffer size check and add it in vimc_cap_buffer_prepare
- vimc_cap_create: remove unecessary check if v4l2_dev or v4l2_dev->dev is null
- vimc_cap_create: only allow a single pad
- vimc_sen_create: only allow source pads, remove unecessary source pads
checks in vimc_thread_sen

Changes since v3: fix rmmod crash and built-in compile
- Re-order unregister calls in vimc_device_unregister function (remove
rmmod issue)
- Call media_device_unregister_entity in vimc_raw_destroy
- Add depends on VIDEO_DEV && VIDEO_V4L2 and select VIDEOBUF2_VMALLOC
- Check *nplanes in queue_setup (this remove v4l2-compliance fail)
- Include <linux/kthread.h> in vimc-sensor.c
- Move include of <linux/slab.h> from vimc-core.c to vimc-core.h
- Generate 60 frames per sec instead of 1 in the sensor

Changes since v2: update with current media master tree
- Add struct media_pipeline in vimc_cap_device
- Use vb2_v4l2_buffer instead of vb2_buffer
- Typos
- Remove usage of entity->type and use entity->function instead
- Remove fmt argument from queue setup
- Use ktime_get_ns instead of v4l2_get_timestamp
- Iterate over link's list using list_for_each_entry
- Use media_device_{init, cleanup}
- Use entity->use_count to keep track of entities instead of the old
entity->id
- Replace media_entity_init by media_entity_pads_init
---
 drivers/media/platform/Kconfig             |   2 +
 drivers/media/platform/Makefile            |   1 +
 drivers/media/platform/vimc/Kconfig        |   7 +
 drivers/media/platform/vimc/Makefile       |   3 +
 drivers/media/platform/vimc/vimc-capture.c | 553 ++++++++++++++++++++++++++
 drivers/media/platform/vimc/vimc-capture.h |  28 ++
 drivers/media/platform/vimc/vimc-core.c    | 600 +++++++++++++++++++++++++++++
 drivers/media/platform/vimc/vimc-core.h    |  57 +++
 drivers/media/platform/vimc/vimc-sensor.c  | 279 ++++++++++++++
 drivers/media/platform/vimc/vimc-sensor.h  |  28 ++
 10 files changed, 1558 insertions(+)
 create mode 100644 drivers/media/platform/vimc/Kconfig
 create mode 100644 drivers/media/platform/vimc/Makefile
 create mode 100644 drivers/media/platform/vimc/vimc-capture.c
 create mode 100644 drivers/media/platform/vimc/vimc-capture.h
 create mode 100644 drivers/media/platform/vimc/vimc-core.c
 create mode 100644 drivers/media/platform/vimc/vimc-core.h
 create mode 100644 drivers/media/platform/vimc/vimc-sensor.c
 create mode 100644 drivers/media/platform/vimc/vimc-sensor.h

Comments

Hans Verkuil Sept. 6, 2016, 7:33 a.m. UTC | #1
On 09/04/16 22:02, Helen Koike wrote:
> From: Helen Fornazier <helen.fornazier@gmail.com>
>
> First version of the Virtual Media Controller.
> Add a simple version of the core of the driver, the capture and
> sensor nodes in the topology, generating a grey image in a hardcoded
> format.
>
> Signed-off-by: Helen Koike <helen.koike@collabora.com>
>

One thing is missing: a MAINTAINERS entry. Can you make a separate patch
updating the MAINTAINERS file?

Thanks!

	Hans

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Laurent Pinchart Jan. 10, 2017, 7:54 p.m. UTC | #2
Hi Helen,

(CC'ing Sakari as there's a question specifically for him)

Thank you for the patch, and so sorry for the late review. 

On Sunday 04 Sep 2016 17:02:18 Helen Koike wrote:
> From: Helen Fornazier <helen.fornazier@gmail.com>
> 
> First version of the Virtual Media Controller.
> Add a simple version of the core of the driver, the capture and
> sensor nodes in the topology, generating a grey image in a hardcoded
> format.
> 
> Signed-off-by: Helen Koike <helen.koike@collabora.com>

I've reviewed the whole patch but haven't had time to test it. I've also 
skipped the items marked as TODO or FIXME as they're obviously not ready yet 
:-) Overall this looks good to me, all the issues are minor.

> ---
> 
> Patch based in media/master tree, and available here:
> https://github.com/helen-fornazier/opw-staging/tree/vimc/devel/vpu
> 
> Changes since v5:
> - Fix message "Entity type for entity Sensor A was not initialized!"
>   by initializing the sensor entity.function after the calling
>   v4l2_subded_init
> - populate device_caps in vimc_cap_create instead of in
>   vimc_cap_querycap
> - Fix typo in vimc-core.c s/de/the
> 
> Changes since v4:
> - coding style fixes
> - remove BUG_ON
> - change copyright to 2016
> - depens on VIDEO_V4L2_SUBDEV_API instead of select
> - remove assignement of V4L2_CAP_DEVICE_CAPS
> - s/vimc_cap_g_fmt_vid_cap/vimc_cap_fmt_vid_cap
> - fix vimc_cap_queue_setup declaration type
> - remove wrong buffer size check and add it in vimc_cap_buffer_prepare
> - vimc_cap_create: remove unecessary check if v4l2_dev or v4l2_dev->dev is
> null - vimc_cap_create: only allow a single pad
> - vimc_sen_create: only allow source pads, remove unecessary source pads
> checks in vimc_thread_sen
> 
> Changes since v3: fix rmmod crash and built-in compile
> - Re-order unregister calls in vimc_device_unregister function (remove
> rmmod issue)
> - Call media_device_unregister_entity in vimc_raw_destroy
> - Add depends on VIDEO_DEV && VIDEO_V4L2 and select VIDEOBUF2_VMALLOC
> - Check *nplanes in queue_setup (this remove v4l2-compliance fail)
> - Include <linux/kthread.h> in vimc-sensor.c
> - Move include of <linux/slab.h> from vimc-core.c to vimc-core.h
> - Generate 60 frames per sec instead of 1 in the sensor
> 
> Changes since v2: update with current media master tree
> - Add struct media_pipeline in vimc_cap_device
> - Use vb2_v4l2_buffer instead of vb2_buffer
> - Typos
> - Remove usage of entity->type and use entity->function instead
> - Remove fmt argument from queue setup
> - Use ktime_get_ns instead of v4l2_get_timestamp
> - Iterate over link's list using list_for_each_entry
> - Use media_device_{init, cleanup}
> - Use entity->use_count to keep track of entities instead of the old
> entity->id
> - Replace media_entity_init by media_entity_pads_init
> ---
>  drivers/media/platform/Kconfig             |   2 +
>  drivers/media/platform/Makefile            |   1 +
>  drivers/media/platform/vimc/Kconfig        |   7 +
>  drivers/media/platform/vimc/Makefile       |   3 +
>  drivers/media/platform/vimc/vimc-capture.c | 553 ++++++++++++++++++++++++++
>  drivers/media/platform/vimc/vimc-capture.h |  28 ++
>  drivers/media/platform/vimc/vimc-core.c    | 600 ++++++++++++++++++++++++++
>  drivers/media/platform/vimc/vimc-core.h    |  57 +++
>  drivers/media/platform/vimc/vimc-sensor.c  | 279 ++++++++++++++
>  drivers/media/platform/vimc/vimc-sensor.h  |  28 ++
>  10 files changed, 1558 insertions(+)
>  create mode 100644 drivers/media/platform/vimc/Kconfig
>  create mode 100644 drivers/media/platform/vimc/Makefile
>  create mode 100644 drivers/media/platform/vimc/vimc-capture.c
>  create mode 100644 drivers/media/platform/vimc/vimc-capture.h
>  create mode 100644 drivers/media/platform/vimc/vimc-core.c
>  create mode 100644 drivers/media/platform/vimc/vimc-core.h
>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.c
>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.h

[snip]

> diff --git a/drivers/media/platform/vimc/vimc-capture.c
> b/drivers/media/platform/vimc/vimc-capture.c new file mode 100644
> index 0000000..b7636cf
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-capture.c

[snip]

> +static void vimc_cap_return_all_buffers(struct vimc_cap_device *vcap,
> +					enum vb2_buffer_state state)
> +{
> +	struct vimc_cap_buffer *vbuf, *node;
> +
> +	spin_lock(&vcap->qlock);
> +
> +	list_for_each_entry_safe(vbuf, node, &vcap->buf_list, list) {
> +		vb2_buffer_done(&vbuf->vb2.vb2_buf, state);
> +		list_del(&vbuf->list);

It shouldn't matter given that you protect this with a spinlock, but moving 
the list_del() above makes the code flow follow a safer order.

> +	}
> +
> +	spin_unlock(&vcap->qlock);
> +}
> +
> +static int vimc_cap_pipeline_s_stream(struct vimc_cap_device *vcap, int
> enable)
> +{
> +	int ret;
> +	struct media_pad *pad;
> +	struct media_entity *entity;
> +	struct v4l2_subdev *sd;
> +
> +	/* Start the stream in the subdevice direct connected */
> +	entity = &vcap->vdev.entity;
> +	pad = media_entity_remote_pad(&entity->pads[0]);
> +
> +	/* If we are not connected to any subdev node, it means there is 
nothing
> +	 * to activate on the pipe (e.g. we can be connected with an input
> +	 * device or we are not connected at all)

Shouldn't this have resulted in a pipeline validation error ?

> +	 */
> +	if (pad == NULL || !is_media_entity_v4l2_subdev(pad->entity))
> +		return 0;
> +
> +	entity = pad->entity;
> +	sd = media_entity_to_v4l2_subdev(entity);
> +
> +	ret = v4l2_subdev_call(sd, video, s_stream, enable);
> +	if (ret && ret != -ENOIOCTLCMD)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int
> count)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> +	struct media_entity *entity;
> +	int ret;
> +
> +	vcap->sequence = 0;
> +
> +	/* Start the media pipeline */
> +	entity = &vcap->vdev.entity;
> +	ret = media_entity_pipeline_start(entity, &vcap->pipe);
> +	if (ret) {
> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
> +		return ret;
> +	}
> +
> +	/* Enable streaming from the pipe */
> +	ret = vimc_cap_pipeline_s_stream(vcap, 1);
> +	if (ret) {

You should call media_entity_pipeline_stop() here.

> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Stop the stream engine. Any remaining buffers in the stream queue are
> + * dequeued and passed on to the vb2 framework marked as STATE_ERROR.
> + */
> +static void vimc_cap_stop_streaming(struct vb2_queue *vq)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> +
> +	/* Disable streaming from the pipe */
> +	vimc_cap_pipeline_s_stream(vcap, 0);
> +
> +	/* Stop the media pipeline */
> +	media_entity_pipeline_stop(&vcap->vdev.entity);
> +
> +	/* Release all active buffers */
> +	vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_ERROR);
> +}
> +
> +static void vimc_cap_buf_queue(struct vb2_buffer *vb2_buf)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb2_buf->vb2_queue);
> +	struct vimc_cap_buffer *buf = container_of(vb2_buf,
> +						   struct vimc_cap_buffer,
> +						   vb2.vb2_buf);
> +
> +	spin_lock(&vcap->qlock);
> +	list_add_tail(&buf->list, &vcap->buf_list);
> +	spin_unlock(&vcap->qlock);
> +}
> +
> +static int vimc_cap_queue_setup(struct vb2_queue *vq, unsigned int
> *nbuffers,
> +				unsigned int *nplanes, unsigned int sizes[],
> +				struct device *alloc_devs[])
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> +
> +	if (*nplanes)

You should also return an error if *nplanes != 1 in this case.

> +		return sizes[0] < vcap->format.sizeimage ? -EINVAL : 0;
> +	/* We don't support multiplanes for now */
> +	*nplanes = 1;
> +	sizes[0] = vcap->format.sizeimage;
> +
> +	return 0;
> +}
> +
> +/*
> + * Prepare the buffer for queueing to the DMA engine: check and set the

There's no DMA engine, this is a virtual device :-)

> + * payload size.
> + */
> +static int vimc_cap_buffer_prepare(struct vb2_buffer *vb)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb->vb2_queue);
> +	unsigned long size = vcap->format.sizeimage;
> +
> +	if (vb2_plane_size(vb, 0) < size) {
> +		dev_err(vcap->dev, "buffer too small (%lu < %lu)\n",
> +			vb2_plane_size(vb, 0), size);
> +		return -EINVAL;
> +	}
> +
> +	vb2_set_plane_payload(vb, 0, size);

If you call this here you don't have to duplicate the call in 
vimc_cap_process_frame(). I would keep the one in vimc_cap_process_frame() and 
remove this one.

> +	return 0;
> +}
> +
> +static const struct vb2_ops vimc_cap_qops = {
> +	.start_streaming	= vimc_cap_start_streaming,
> +	.stop_streaming		= vimc_cap_stop_streaming,
> +	.buf_queue		= vimc_cap_buf_queue,
> +	.queue_setup		= vimc_cap_queue_setup,
> +	.buf_prepare		= vimc_cap_buffer_prepare,
> +	/*
> +	 * Since q->lock is set we can use the standard
> +	 * vb2_ops_wait_prepare/finish helper functions.
> +	 */
> +	.wait_prepare		= vb2_ops_wait_prepare,
> +	.wait_finish		= vb2_ops_wait_finish,
> +};
> +
> +/* NOTE: this function is a copy of v4l2_subdev_link_validate_get_format
> + * maybe the v4l2 function should be public
> + */

Or we should add a standard subdev <-> video devnode link validation function 
in the core :-) So far all drivers validate that link manually, but I don't 
remember a good reason why that couldn't be performed by the link validation 
infrastructure. Sakari, what do you think ?

That's anyway not a blocker to get this patch merged.

> +static int vimc_cap_v4l2_subdev_link_validate_get_format(struct media_pad
> *pad,
> +						struct v4l2_subdev_format 
*fmt)
> +{
> +	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(pad->entity);
> +
> +	fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
> +	fmt->pad = pad->index;
> +	return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);
> +}
> +
> +static int vimc_cap_link_validate(struct media_link *link)
> +{
> +	struct v4l2_subdev_format source_fmt;
> +	struct v4l2_pix_format *sink_fmt;
> +	struct vimc_cap_device *vcap;
> +	const struct vimc_pix_map *vpix;
> +	int ret;
> +
> +	/* Retrieve the video capture device */
> +	vcap = container_of(link->sink->entity,
> +			    struct vimc_cap_device, vdev.entity);
> +
> +	/* If the connected node is not a subdevice type
> +	 * then it's a raw node from vimc-core, ignore the link for now
> +	 * TODO: remove this when there are no more raw nodes in the
> +	 * core and return error instead
> +	 */
> +	if (!is_media_entity_v4l2_subdev(link->source->entity))
> +		return 0;
> +
> +	/* Get the the format of the video device */
> +	sink_fmt = &vcap->format;
> +
> +	/* Get the the format of the subdev */
> +	ret = vimc_cap_v4l2_subdev_link_validate_get_format(link->source,
> +							    &source_fmt);
> +	if (ret)
> +		return ret;
> +
> +	dev_dbg(vcap->dev,
> +		"cap: %s: link validate formats src:%dx%d %d sink:%dx%d %d\n",
> +		vcap->vdev.name,
> +		source_fmt.format.width, source_fmt.format.height,
> +		source_fmt.format.code,
> +		sink_fmt->width, sink_fmt->height,
> +		sink_fmt->pixelformat);
> +
> +	/* Validate the format */
> +
> +	vpix = vimc_pix_map_by_pixelformat(sink_fmt->pixelformat);
> +	if (!vpix)
> +		return -EINVAL;

This can't happen, it should be caught by the set format handler. The driver 
should not allowed the stored pixel format to ever be invalid.

> +	/* The width, height and code must match. */
> +	if (source_fmt.format.width != sink_fmt->width
> +	    || source_fmt.format.height != sink_fmt->height
> +	    || vpix->code != source_fmt.format.code)
> +		return -EINVAL;
> +
> +	/* The field order must match, or the sink field order must be NONE
> +	 * to support interlaced hardware connected to bridges that support
> +	 * progressive formats only.
> +	 */
> +	if (source_fmt.format.field != sink_fmt->field &&
> +	    sink_fmt->field != V4L2_FIELD_NONE)
> +		return -EINVAL;
> +
> +	return 0;
> +}

[snip]

> +struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
> +					const char *const name,
> +					u16 num_pads,
> +					const unsigned long *pads_flag)
> +{
> +	int ret;
> +	struct vb2_queue *q;
> +	struct video_device *vdev;
> +	struct vimc_cap_device *vcap;
> +	const struct vimc_pix_map *vpix;
> +
> +	/* Check entity configuration params
> +	 * NOTE: we only support a single sink pad
> +	 */
> +	if (!name || num_pads != 1 || !pads_flag ||
> +	    !(pads_flag[0] & MEDIA_PAD_FL_SINK))
> +		return ERR_PTR(-EINVAL);
> +
> +	/* Allocate the vimc_cap_device struct */
> +	vcap = kzalloc(sizeof(*vcap), GFP_KERNEL);
> +	if (!vcap)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Link the vimc_cap_device struct with v4l2 and dev parent */
> +	vcap->v4l2_dev = v4l2_dev;
> +	vcap->dev = v4l2_dev->dev;
> +
> +	/* Allocate the pads */
> +	vcap->ved.pads = vimc_pads_init(num_pads, pads_flag);
> +	if (IS_ERR(vcap->ved.pads)) {
> +		ret = PTR_ERR(vcap->ved.pads);
> +		goto err_free_vcap;
> +	}
> +
> +	/* Initialize the media entity */
> +	vcap->vdev.entity.name = name;
> +	vcap->vdev.entity.function = MEDIA_ENT_F_IO_V4L;
> +	ret = media_entity_pads_init(&vcap->vdev.entity,
> +				     num_pads, vcap->ved.pads);
> +	if (ret)
> +		goto err_clean_pads;
> +
> +	/* Initialize the lock */
> +	mutex_init(&vcap->lock);
> +
> +	/* Initialize the vb2 queue */
> +	q = &vcap->queue;
> +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	q->io_modes = VB2_MMAP | VB2_DMABUF;
> +	q->drv_priv = vcap;
> +	q->buf_struct_size = sizeof(struct vimc_cap_buffer);
> +	q->ops = &vimc_cap_qops;
> +	q->mem_ops = &vb2_vmalloc_memops;
> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	q->min_buffers_needed = 2;
> +	q->lock = &vcap->lock;
> +
> +	ret = vb2_queue_init(q);
> +	if (ret) {
> +		dev_err(vcap->dev,
> +			"vb2 queue init failed (err=%d)\n", ret);
> +		goto err_clean_m_ent;
> +	}
> +
> +	/* Initialize buffer list and its lock */
> +	INIT_LIST_HEAD(&vcap->buf_list);
> +	spin_lock_init(&vcap->qlock);
> +
> +	/* Set the frame format (this is hardcoded for now) */
> +	vcap->format.width = 640;
> +	vcap->format.height = 480;
> +	vcap->format.pixelformat = V4L2_PIX_FMT_RGB24;
> +	vcap->format.field = V4L2_FIELD_NONE;
> +	vcap->format.colorspace = V4L2_COLORSPACE_SRGB;
> +
> +	vpix = vimc_pix_map_by_pixelformat(vcap->format.pixelformat);
> +
> +	vcap->format.bytesperline = vcap->format.width * vpix->bpp;
> +	vcap->format.sizeimage = vcap->format.bytesperline *
> +				 vcap->format.height;
> +
> +	/* Fill the vimc_ent_device struct */
> +	vcap->ved.destroy = vimc_cap_destroy;
> +	vcap->ved.ent = &vcap->vdev.entity;
> +	vcap->ved.process_frame = vimc_cap_process_frame;
> +
> +	/* Initialize the video_device struct */
> +	vdev = &vcap->vdev;
> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
> +	vdev->entity.ops = &vimc_cap_mops;
> +	vdev->release = video_device_release_empty;

This will result in a crash if you keep the video device node open and unbind 
the vimc device from the driver. However, as the same issue in the media 
controller core hasn't been solved yet, I'm fine fixing all those problems in 
one go later.

> +	vdev->fops = &vimc_cap_fops;
> +	vdev->ioctl_ops = &vimc_cap_ioctl_ops;
> +	vdev->lock = &vcap->lock;
> +	vdev->queue = q;
> +	vdev->v4l2_dev = vcap->v4l2_dev;
> +	vdev->vfl_dir = VFL_DIR_RX;
> +	strlcpy(vdev->name, name, sizeof(vdev->name));
> +	video_set_drvdata(vdev, vcap);
> +
> +	/* Register the video_device with the v4l2 and the media framework */
> +	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
> +	if (ret) {
> +		dev_err(vcap->dev,
> +			"video register failed (err=%d)\n", ret);
> +		goto err_release_queue;
> +	}
> +
> +	return &vcap->ved;
> +
> +err_release_queue:
> +	vb2_queue_release(q);
> +err_clean_m_ent:
> +	media_entity_cleanup(&vcap->vdev.entity);
> +err_clean_pads:
> +	vimc_pads_cleanup(vcap->ved.pads);
> +err_free_vcap:
> +	kfree(vcap);
> +
> +	return ERR_PTR(ret);
> +}

[snip]

> diff --git a/drivers/media/platform/vimc/vimc-core.c
> b/drivers/media/platform/vimc/vimc-core.c new file mode 100644
> index 0000000..0a2b91b
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-core.c

[snip]

> +#define VIMC_ENT_LINK(src, srcpad, sink, sinkpad, link_flags) {	\
> +	.src_ent = src,						\
> +	.src_pad = srcpad,					\
> +	.sink_ent = sink,					\
> +	.sink_pad = sinkpad,					\
> +	.flags = link_flags,					\
> +}
> +
> +#define VIMC_PIX_MAP(_code, _bpp, _pixelformat) {	\
> +	.code = _code,					\
> +	.pixelformat = _pixelformat,			\
> +	.bpp = _bpp,					\
> +}
> +
> +struct vimc_device {
> +	/* The pipeline configuration
> +	 * (filled before calling vimc_device_register)
> +	 */
> +	const struct vimc_pipeline_config *pipe_cfg;
> +
> +	/* The Associated media_device parent */
> +	struct media_device mdev;
> +
> +	/* Internal v4l2 parent device*/
> +	struct v4l2_device v4l2_dev;
> +
> +	/* Internal topology */
> +	struct vimc_ent_device **ved;
> +};
> +
> +/**
> + * enum vimc_ent_node - Select the functionality of a node in the topology
> + * @VIMC_ENT_NODE_SENSOR:	A node of type SENSOR simulates a camera 
sensor
> + *				generating internal images in bayer format and
> + *				propagating those images through the pipeline
> + * @VIMC_ENT_NODE_CAPTURE:	A node of type CAPTURE is a v4l2 video_device
> + *				that exposes the received image from the
> + *				pipeline to the user space
> + * @VIMC_ENT_NODE_INPUT:	A node of type INPUT is a v4l2 video_device 
that
> + *				receives images from the user space and
> + *				propagates them through the pipeline
> + * @VIMC_ENT_NODE_DEBAYER:	A node type DEBAYER expects to receive a frame
> + *				in bayer format converts it to RGB
> + * @VIMC_ENT_NODE_SCALER:	A node of type SCALER scales the received 
image
> + *				by a given multiplier
> + *
> + * This enum is used in the entity configuration struct to allow the
> definition + * of a custom topology specifying the role of each node on it.
> + */
> +enum vimc_ent_node {
> +	VIMC_ENT_NODE_SENSOR,
> +	VIMC_ENT_NODE_CAPTURE,
> +	VIMC_ENT_NODE_INPUT,
> +	VIMC_ENT_NODE_DEBAYER,
> +	VIMC_ENT_NODE_SCALER,
> +};
> +
> +/* Structure which describes individual configuration for each entity */
> +struct vimc_ent_config {
> +	const char *name;
> +	size_t pads_qty;
> +	const unsigned long *pads_flag;
> +	enum vimc_ent_node node;
> +};
> +
> +/* Structure which describes links between entities */
> +struct vimc_ent_link {
> +	unsigned int src_ent;
> +	u16 src_pad;
> +	unsigned int sink_ent;
> +	u16 sink_pad;
> +	u32 flags;
> +};
> +
> +/* Structure which describes the whole topology */
> +struct vimc_pipeline_config {
> +	const struct vimc_ent_config *ents;
> +	size_t num_ents;
> +	const struct vimc_ent_link *links;
> +	size_t num_links;
> +};
> +
> +/*
> --------------------------------------------------------------------------
> + * Topology Configuration
> + */
> +
> +static const struct vimc_ent_config ent_config[] = {
> +	{
> +		.name = "Sensor A",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_SENSOR,
> +	},
> +	{
> +		.name = "Sensor B",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_SENSOR,
> +	},
> +	{
> +		.name = "Debayer A",
> +		.pads_qty = 2,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
> +						     MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_DEBAYER,
> +	},
> +	{
> +		.name = "Debayer B",
> +		.pads_qty = 2,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
> +						     MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_DEBAYER,
> +	},
> +	{
> +		.name = "Raw Capture 0",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
> +		.node = VIMC_ENT_NODE_CAPTURE,
> +	},
> +	{
> +		.name = "Raw Capture 1",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
> +		.node = VIMC_ENT_NODE_CAPTURE,
> +	},
> +	{
> +		.name = "RGB/YUV Input",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_INPUT,
> +	},
> +	{
> +		.name = "Scaler",
> +		.pads_qty = 2,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
> +						     MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_SCALER,
> +	},
> +	{
> +		.name = "RGB/YUV Capture",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
> +		.node = VIMC_ENT_NODE_CAPTURE,
> +	},
> +};
> +
> +static const struct vimc_ent_link ent_links[] = {
> +	/* Link: Sensor A (Pad 0)->(Pad 0) Debayer A */
> +	VIMC_ENT_LINK(0, 0, 2, 0, MEDIA_LNK_FL_ENABLED | 
MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Sensor A (Pad 0)->(Pad 0) Raw Capture 0 */
> +	VIMC_ENT_LINK(0, 0, 4, 0, MEDIA_LNK_FL_ENABLED | 
MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Sensor B (Pad 0)->(Pad 0) Debayer B */
> +	VIMC_ENT_LINK(1, 0, 3, 0, MEDIA_LNK_FL_ENABLED | 
MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Sensor B (Pad 0)->(Pad 0) Raw Capture 1 */
> +	VIMC_ENT_LINK(1, 0, 5, 0, MEDIA_LNK_FL_ENABLED | 
MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Debayer A (Pad 1)->(Pad 0) Scaler */
> +	VIMC_ENT_LINK(2, 1, 7, 0, MEDIA_LNK_FL_ENABLED),
> +	/* Link: Debayer B (Pad 1)->(Pad 0) Scaler */
> +	VIMC_ENT_LINK(3, 1, 7, 0, 0),
> +	/* Link: RGB/YUV Input (Pad 0)->(Pad 0) Scaler */
> +	VIMC_ENT_LINK(6, 0, 7, 0, 0),
> +	/* Link: Scaler (Pad 1)->(Pad 0) RGB/YUV Capture */
> +	VIMC_ENT_LINK(7, 1, 8, 0, MEDIA_LNK_FL_ENABLED | 
MEDIA_LNK_FL_IMMUTABLE),
> +};
> +
> +static const struct vimc_pipeline_config pipe_cfg = {
> +	.ents		= ent_config,
> +	.num_ents	= ARRAY_SIZE(ent_config),
> +	.links		= ent_links,
> +	.num_links	= ARRAY_SIZE(ent_links)
> +};
> +
> +/* --------------------------------------------------------------------- */
> +
> +static void vimc_dev_release(struct device *dev)
> +{}

Missing line break between the braces.

> +
> +static struct platform_device vimc_pdev = {
> +	.name		= VIMC_PDEV_NAME,
> +	.dev.release	= vimc_dev_release,
> +};
> +
> +const struct vimc_pix_map vimc_pix_map_list[] = {

This array isn't used outside of the compilation unit, you can make it static.

> +	/* TODO: add all missing formats */
> +
> +	/* RGB formats */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_BGR888_1X24, 3, V4L2_PIX_FMT_BGR24),

Is there really an added value in using the macro compared to direct array 
initialization ?

> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_RGB888_1X24, 3, V4L2_PIX_FMT_RGB24),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_ARGB8888_1X32, 4, V4L2_PIX_FMT_ARGB32),
> +
> +	/* Bayer formats */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR8_1X8, 1, V4L2_PIX_FMT_SBGGR8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG8_1X8, 1, V4L2_PIX_FMT_SGBRG8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG8_1X8, 1, V4L2_PIX_FMT_SGRBG8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB8_1X8, 1, V4L2_PIX_FMT_SRGGB8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_1X10, 2, V4L2_PIX_FMT_SBGGR10),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_1X10, 2, V4L2_PIX_FMT_SGBRG10),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_1X10, 2, V4L2_PIX_FMT_SGRBG10),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_1X10, 2, V4L2_PIX_FMT_SRGGB10),
> +	/* 10bit raw bayer a-law compressed to 8 bits */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_ALAW8_1X8, 1,
> V4L2_PIX_FMT_SBGGR10ALAW8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_ALAW8_1X8, 1,
> V4L2_PIX_FMT_SGBRG10ALAW8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_ALAW8_1X8, 1,
> V4L2_PIX_FMT_SGRBG10ALAW8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_ALAW8_1X8, 1,
> V4L2_PIX_FMT_SRGGB10ALAW8),
> +	/* 10bit raw bayer DPCM compressed to 8 bits */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_DPCM8_1X8, 1,
> V4L2_PIX_FMT_SBGGR10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_DPCM8_1X8, 1,
> V4L2_PIX_FMT_SGBRG10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_DPCM8_1X8, 1,
> V4L2_PIX_FMT_SGRBG10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_DPCM8_1X8, 1, 
V4L2_PIX_FMT_SRGGB10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR12_1X12, 2, V4L2_PIX_FMT_SBGGR12),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG12_1X12, 2, V4L2_PIX_FMT_SGBRG12),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG12_1X12, 2, V4L2_PIX_FMT_SGRBG12),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB12_1X12, 2, V4L2_PIX_FMT_SRGGB12),
> +
> +	/* End */
> +	{0, 0, 0}
> +};
> +
> +const struct vimc_pix_map *vimc_pix_map_by_code(u32 code)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {

You can use i < ARRAY_SIZE(vimc_pix_map_list) as the condition here and in the 
function below, and get rid of the termination marker in the array.

> +		if (vimc_pix_map_list[i].code == code)
> +			return &vimc_pix_map_list[i];
> +	}
> +	return NULL;
> +}
> +
> +const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
> +		if (vimc_pix_map_list[i].pixelformat == pixelformat)
> +			return &vimc_pix_map_list[i];
> +	}
> +	return NULL;
> +}

[snip]

> +/* TODO: remove this function when all the
> + * entities specific code are implemented
> + */
> +static struct vimc_ent_device *vimc_raw_create(struct v4l2_device
> *v4l2_dev,
> +					       const char *const name,
> +					       u16 num_pads,
> +					       const unsigned long *pads_flag)
> +{
> +	int ret;
> +	struct vimc_ent_device *ved;
> +
> +	/* Allocate the main ved struct */
> +	ved = kzalloc(sizeof(*ved), GFP_KERNEL);
> +	if (!ved)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Allocate the media entity */
> +	ved->ent = kzalloc(sizeof(*ved->ent), GFP_KERNEL);
> +	if (!ved->ent) {
> +		ret = -ENOMEM;
> +		goto err_free_ved;
> +	}
> +
> +	/* Allocate the pads */
> +	ved->pads = vimc_pads_init(num_pads, pads_flag);
> +	if (IS_ERR(ved->pads)) {
> +		ret = PTR_ERR(ved->pads);
> +		goto err_free_ent;
> +	}
> +
> +	/* Initialize the media entity */
> +	ved->ent->name = name;
> +	ved->ent->function = MEDIA_ENT_F_IO_V4L;

This isn't a video node. You can use MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN for now.

> +	ret = media_entity_pads_init(ved->ent, num_pads, ved->pads);
> +	if (ret)
> +		goto err_cleanup_pads;
> +
> +	/* Register the media entity */
> +	ret = media_device_register_entity(v4l2_dev->mdev, ved->ent);
> +	if (ret)
> +		goto err_cleanup_entity;
> +
> +	/* Fill out the destroy function and return */
> +	ved->destroy = vimc_raw_destroy;
> +	return ved;
> +
> +err_cleanup_entity:
> +	media_entity_cleanup(ved->ent);
> +err_cleanup_pads:
> +	vimc_pads_cleanup(ved->pads);
> +err_free_ent:
> +	kfree(ved->ent);
> +err_free_ved:
> +	kfree(ved);
> +
> +	return ERR_PTR(ret);
> +}
> +
> +static int vimc_device_register(struct vimc_device *vimc)
> +{
> +	unsigned int i;
> +	int ret = 0;

There's no need to assign 0 to ret here.

> +	/* Allocate memory for the vimc_ent_devices pointers */
> +	vimc->ved = devm_kcalloc(vimc->mdev.dev, vimc->pipe_cfg->num_ents,
> +				 sizeof(*vimc->ved), GFP_KERNEL);
> +	if (!vimc->ved)
> +		return -ENOMEM;
> +
> +	/* Register the media device */
> +	ret = media_device_register(&vimc->mdev);

Shouldn't you register the media device after creating the entities and links 
?

> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"media device register failed (err=%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Link the media device within the v4l2_device */
> +	vimc->v4l2_dev.mdev = &vimc->mdev;
> +
> +	/* Register the v4l2 struct */
> +	ret = v4l2_device_register(vimc->mdev.dev, &vimc->v4l2_dev);
> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"v4l2 device register failed (err=%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Initialize entities */
> +	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
> +		struct vimc_ent_device *(*create_func)(struct v4l2_device *,
> +						       const char *const,
> +						       u16,
> +						       const unsigned long *);
> +
> +		/* Register the specific node */
> +		switch (vimc->pipe_cfg->ents[i].node) {
> +		case VIMC_ENT_NODE_SENSOR:
> +			create_func = vimc_sen_create;
> +			break;
> +
> +		case VIMC_ENT_NODE_CAPTURE:
> +			create_func = vimc_cap_create;
> +			break;
> +
> +		/* TODO: Instantiate the specific topology node */
> +		case VIMC_ENT_NODE_INPUT:
> +		case VIMC_ENT_NODE_DEBAYER:
> +		case VIMC_ENT_NODE_SCALER:
> +		default:
> +			/* TODO: remove this when all the entities specific
> +			 * code are implemented
> +			 */
> +			create_func = vimc_raw_create;
> +			break;
> +		}
> +
> +		vimc->ved[i] = create_func(&vimc->v4l2_dev,
> +					   vimc->pipe_cfg->ents[i].name,
> +					   vimc->pipe_cfg->ents[i].pads_qty,
> +					   vimc->pipe_cfg->ents[i].pads_flag);
> +		if (IS_ERR(vimc->ved[i])) {
> +			ret = PTR_ERR(vimc->ved[i]);
> +			vimc->ved[i] = NULL;
> +			goto err;
> +		}
> +
> +		/* Set use_count to keep track of the ved structure */
> +		vimc->ved[i]->ent->use_count = i;

The media_entity::use_count field is managed by the media controller core. You 
can't use it for your own purpose.

> +	}
> +
> +	/* Initialize the links between entities */
> +	for (i = 0; i < vimc->pipe_cfg->num_links; i++) {
> +		const struct vimc_ent_link *link = &vimc->pipe_cfg->links[i];
> +
> +		ret = media_create_pad_link(vimc->ved[link->src_ent]->ent,
> +					    link->src_pad,
> +					    vimc->ved[link->sink_ent]->ent,
> +					    link->sink_pad,
> +					    link->flags);
> +		if (ret)
> +			goto err;
> +	}
> +
> +	/* Expose all subdev's nodes*/
> +	ret = v4l2_device_register_subdev_nodes(&vimc->v4l2_dev);
> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"vimc subdev nodes registration failed (err=%d)\n",
> +			ret);
> +		goto err;
> +	}
> +
> +	return 0;
> +
> +err:
> +	/* Destroy the so far created topology */
> +	vimc_device_unregister(vimc);
> +
> +	return ret;
> +}
> +
> +static int vimc_probe(struct platform_device *pdev)
> +{
> +	struct vimc_device *vimc;
> +	int ret;
> +
> +	/* Prepare the vimc topology structure */
> +
> +	/* Allocate memory for the vimc structure */
> +	vimc = devm_kzalloc(&pdev->dev, sizeof(*vimc), GFP_KERNEL);
> +	if (!vimc)
> +		return -ENOMEM;

We have recently come to an agreement that devm_kzalloc() is harmful to 
allocate structures that embed instances of struct media_device. While this is 
still an unresolved problem, could you please use kzalloc() to avoid making it 
worse ? It will require a kfree() in the error paths and in the remove 
handler.

> +	/* Set the pipeline configuration struct */
> +	vimc->pipe_cfg = &pipe_cfg;
> +
> +	/* Initialize media device */
> +	strlcpy(vimc->mdev.model, VIMC_MDEV_MODEL_NAME,
> +		sizeof(vimc->mdev.model));
> +	vimc->mdev.dev = &pdev->dev;
> +	media_device_init(&vimc->mdev);
> +
> +	/* Create vimc topology */
> +	ret = vimc_device_register(vimc);
> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"vimc device registration failed (err=%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Link the topology object with the platform device object */
> +	platform_set_drvdata(pdev, vimc);
> +
> +	return 0;
> +}
> +
> +static int vimc_remove(struct platform_device *pdev)
> +{
> +	struct vimc_device *vimc;
> +
> +	/* Get the topology object linked with the platform device object */
> +	vimc = platform_get_drvdata(pdev);

You could combine that in a single line

	struct vimc_device *vimc = platform_get_drvdata(pdev);

I understand that the comment was written when you had less experience with 
the kernel code which pushed you on the side of verbosity, but I believe it's 
not really needed :-)

> +
> +	/* Destroy all the topology */
> +	vimc_device_unregister(vimc);
> +
> +	return 0;
> +}

[snip]

> diff --git a/drivers/media/platform/vimc/vimc-sensor.c
> b/drivers/media/platform/vimc/vimc-sensor.c new file mode 100644
> index 0000000..174e5dc
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-sensor.c

[snip]

> +static int vimc_thread_sen(void *data)
> +{
> +	unsigned int i;
> +	struct vimc_sen_device *vsen = data;
> +
> +	set_freezable();
> +
> +	for (;;) {
> +		try_to_freeze();
> +		if (kthread_should_stop())
> +			break;
> +
> +		memset(vsen->frame, 100, vsen->frame_size);
> +
> +		/* Send the frame to all source pads */
> +		for (i = 0; i < vsen->sd.entity.num_pads; i++)
> +			vimc_propagate_frame(vsen->dev,
> +					     &vsen->sd.entity.pads[i],
> +					     vsen->frame);
> +
> +		/* 60 frames per second */
> +		schedule_timeout_interruptible(HZ/60);

What can this be interrupted by ?

> +	}
> +
> +	return 0;
> +}

[snip]

> +struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
> +					const char *const name,
> +					u16 num_pads,
> +					const unsigned long *pads_flag)
> +{
> +	int ret;
> +	unsigned int i;
> +	struct vimc_sen_device *vsen;
> +
> +	if (!name || (num_pads && !pads_flag))
> +		return ERR_PTR(-EINVAL);

I think you need at least one pad. Or actually, exactly one pad.

> +	/* check if all pads are sources */
> +	for (i = 0; i < num_pads; i++)
> +		if (!(pads_flag[i] & MEDIA_PAD_FL_SOURCE))
> +			return ERR_PTR(-EINVAL);
> +
> +	/* Allocate the vsen struct */
> +	vsen = kzalloc(sizeof(*vsen), GFP_KERNEL);
> +	if (!vsen)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Link the vimc_sen_device struct with the v4l2 parent */
> +	vsen->v4l2_dev = v4l2_dev;
> +	/* Link the vimc_sen_device struct with the dev parent */
> +	vsen->dev = v4l2_dev->dev;
> +
> +	/* Allocate the pads */
> +	vsen->ved.pads = vimc_pads_init(num_pads, pads_flag);
> +	if (IS_ERR(vsen->ved.pads)) {
> +		ret = PTR_ERR(vsen->ved.pads);
> +		goto err_free_vsen;
> +	}
> +
> +	/* Initialize the media entity */
> +	vsen->sd.entity.name = name;
> +	ret = media_entity_pads_init(&vsen->sd.entity,
> +				     num_pads, vsen->ved.pads);
> +	if (ret)
> +		goto err_clean_pads;
> +
> +	/* Set the active frame format (this is hardcoded for now) */
> +	vsen->mbus_format.width = 640;
> +	vsen->mbus_format.height = 480;
> +	vsen->mbus_format.code = MEDIA_BUS_FMT_RGB888_1X24;
> +	vsen->mbus_format.field = V4L2_FIELD_NONE;
> +	vsen->mbus_format.colorspace = V4L2_COLORSPACE_SRGB;
> +	vsen->mbus_format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
> +	vsen->mbus_format.xfer_func = V4L2_XFER_FUNC_SRGB;
> +
> +	/* Fill the vimc_ent_device struct */
> +	vsen->ved.destroy = vimc_sen_destroy;
> +	vsen->ved.ent = &vsen->sd.entity;
> +
> +	/* Initialize the subdev */
> +	v4l2_subdev_init(&vsen->sd, &vimc_sen_ops);
> +	vsen->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> +	vsen->sd.entity.ops = &vimc_sen_mops;
> +	vsen->sd.owner = THIS_MODULE;
> +	strlcpy(vsen->sd.name, name, sizeof(vsen->sd.name));
> +	v4l2_set_subdevdata(&vsen->sd, vsen);
> +
> +	/* Expose this subdev to user space */
> +	vsen->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
> +
> +	/* Register the subdev with the v4l2 and the media framework */
> +	ret = v4l2_device_register_subdev(vsen->v4l2_dev, &vsen->sd);
> +	if (ret) {
> +		dev_err(vsen->dev,
> +			"subdev register failed (err=%d)\n", ret);
> +		goto err_clean_m_ent;
> +	}
> +
> +	return &vsen->ved;
> +
> +err_clean_m_ent:
> +	media_entity_cleanup(&vsen->sd.entity);
> +err_clean_pads:
> +	vimc_pads_cleanup(vsen->ved.pads);
> +err_free_vsen:
> +	kfree(vsen);
> +
> +	return ERR_PTR(ret);
> +}

[snip]
Helen Koike Jan. 11, 2017, 1:30 a.m. UTC | #3
Hi Laurent,

On 2017-01-10 04:54 PM, Laurent Pinchart wrote:
> Hi Helen,
>
> (CC'ing Sakari as there's a question specifically for him)
>
> Thank you for the patch, and so sorry for the late review.
>
> On Sunday 04 Sep 2016 17:02:18 Helen Koike wrote:
>> From: Helen Fornazier <helen.fornazier@gmail.com>
>>
>> First version of the Virtual Media Controller.
>> Add a simple version of the core of the driver, the capture and
>> sensor nodes in the topology, generating a grey image in a hardcoded
>> format.
>>
>> Signed-off-by: Helen Koike <helen.koike@collabora.com>
>
> I've reviewed the whole patch but haven't had time to test it. I've also
> skipped the items marked as TODO or FIXME as they're obviously not ready yet
> :-) Overall this looks good to me, all the issues are minor.
>
>> ---
>>
>> Patch based in media/master tree, and available here:
>> https://github.com/helen-fornazier/opw-staging/tree/vimc/devel/vpu
>>
>> Changes since v5:
>> - Fix message "Entity type for entity Sensor A was not initialized!"
>>   by initializing the sensor entity.function after the calling
>>   v4l2_subded_init
>> - populate device_caps in vimc_cap_create instead of in
>>   vimc_cap_querycap
>> - Fix typo in vimc-core.c s/de/the
>>
>> Changes since v4:
>> - coding style fixes
>> - remove BUG_ON
>> - change copyright to 2016
>> - depens on VIDEO_V4L2_SUBDEV_API instead of select
>> - remove assignement of V4L2_CAP_DEVICE_CAPS
>> - s/vimc_cap_g_fmt_vid_cap/vimc_cap_fmt_vid_cap
>> - fix vimc_cap_queue_setup declaration type
>> - remove wrong buffer size check and add it in vimc_cap_buffer_prepare
>> - vimc_cap_create: remove unecessary check if v4l2_dev or v4l2_dev->dev is
>> null - vimc_cap_create: only allow a single pad
>> - vimc_sen_create: only allow source pads, remove unecessary source pads
>> checks in vimc_thread_sen
>>
>> Changes since v3: fix rmmod crash and built-in compile
>> - Re-order unregister calls in vimc_device_unregister function (remove
>> rmmod issue)
>> - Call media_device_unregister_entity in vimc_raw_destroy
>> - Add depends on VIDEO_DEV && VIDEO_V4L2 and select VIDEOBUF2_VMALLOC
>> - Check *nplanes in queue_setup (this remove v4l2-compliance fail)
>> - Include <linux/kthread.h> in vimc-sensor.c
>> - Move include of <linux/slab.h> from vimc-core.c to vimc-core.h
>> - Generate 60 frames per sec instead of 1 in the sensor
>>
>> Changes since v2: update with current media master tree
>> - Add struct media_pipeline in vimc_cap_device
>> - Use vb2_v4l2_buffer instead of vb2_buffer
>> - Typos
>> - Remove usage of entity->type and use entity->function instead
>> - Remove fmt argument from queue setup
>> - Use ktime_get_ns instead of v4l2_get_timestamp
>> - Iterate over link's list using list_for_each_entry
>> - Use media_device_{init, cleanup}
>> - Use entity->use_count to keep track of entities instead of the old
>> entity->id
>> - Replace media_entity_init by media_entity_pads_init
>> ---
>>  drivers/media/platform/Kconfig             |   2 +
>>  drivers/media/platform/Makefile            |   1 +
>>  drivers/media/platform/vimc/Kconfig        |   7 +
>>  drivers/media/platform/vimc/Makefile       |   3 +
>>  drivers/media/platform/vimc/vimc-capture.c | 553 ++++++++++++++++++++++++++
>>  drivers/media/platform/vimc/vimc-capture.h |  28 ++
>>  drivers/media/platform/vimc/vimc-core.c    | 600 ++++++++++++++++++++++++++
>>  drivers/media/platform/vimc/vimc-core.h    |  57 +++
>>  drivers/media/platform/vimc/vimc-sensor.c  | 279 ++++++++++++++
>>  drivers/media/platform/vimc/vimc-sensor.h  |  28 ++
>>  10 files changed, 1558 insertions(+)
>>  create mode 100644 drivers/media/platform/vimc/Kconfig
>>  create mode 100644 drivers/media/platform/vimc/Makefile
>>  create mode 100644 drivers/media/platform/vimc/vimc-capture.c
>>  create mode 100644 drivers/media/platform/vimc/vimc-capture.h
>>  create mode 100644 drivers/media/platform/vimc/vimc-core.c
>>  create mode 100644 drivers/media/platform/vimc/vimc-core.h
>>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.c
>>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.h
>
> [snip]
>
>> diff --git a/drivers/media/platform/vimc/vimc-capture.c
>> b/drivers/media/platform/vimc/vimc-capture.c new file mode 100644
>> index 0000000..b7636cf
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-capture.c
>
> [snip]
>
>> +static void vimc_cap_return_all_buffers(struct vimc_cap_device *vcap,
>> +					enum vb2_buffer_state state)
>> +{
>> +	struct vimc_cap_buffer *vbuf, *node;
>> +
>> +	spin_lock(&vcap->qlock);
>> +
>> +	list_for_each_entry_safe(vbuf, node, &vcap->buf_list, list) {
>> +		vb2_buffer_done(&vbuf->vb2.vb2_buf, state);
>> +		list_del(&vbuf->list);
>
> It shouldn't matter given that you protect this with a spinlock, but moving
> the list_del() above makes the code flow follow a safer order.
>
>> +	}
>> +
>> +	spin_unlock(&vcap->qlock);
>> +}
>> +
>> +static int vimc_cap_pipeline_s_stream(struct vimc_cap_device *vcap, int
>> enable)
>> +{
>> +	int ret;
>> +	struct media_pad *pad;
>> +	struct media_entity *entity;
>> +	struct v4l2_subdev *sd;
>> +
>> +	/* Start the stream in the subdevice direct connected */
>> +	entity = &vcap->vdev.entity;
>> +	pad = media_entity_remote_pad(&entity->pads[0]);
>> +
>> +	/* If we are not connected to any subdev node, it means there is
> nothing
>> +	 * to activate on the pipe (e.g. we can be connected with an input
>> +	 * device or we are not connected at all)
>
> Shouldn't this have resulted in a pipeline validation error ?
>
>> +	 */
>> +	if (pad == NULL || !is_media_entity_v4l2_subdev(pad->entity))
>> +		return 0;
>> +
>> +	entity = pad->entity;
>> +	sd = media_entity_to_v4l2_subdev(entity);
>> +
>> +	ret = v4l2_subdev_call(sd, video, s_stream, enable);
>> +	if (ret && ret != -ENOIOCTLCMD)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int
>> count)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>> +	struct media_entity *entity;
>> +	int ret;
>> +
>> +	vcap->sequence = 0;
>> +
>> +	/* Start the media pipeline */
>> +	entity = &vcap->vdev.entity;
>> +	ret = media_entity_pipeline_start(entity, &vcap->pipe);
>> +	if (ret) {
>> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
>> +		return ret;
>> +	}
>> +
>> +	/* Enable streaming from the pipe */
>> +	ret = vimc_cap_pipeline_s_stream(vcap, 1);
>> +	if (ret) {
>
> You should call media_entity_pipeline_stop() here.
>
>> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Stop the stream engine. Any remaining buffers in the stream queue are
>> + * dequeued and passed on to the vb2 framework marked as STATE_ERROR.
>> + */
>> +static void vimc_cap_stop_streaming(struct vb2_queue *vq)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>> +
>> +	/* Disable streaming from the pipe */
>> +	vimc_cap_pipeline_s_stream(vcap, 0);
>> +
>> +	/* Stop the media pipeline */
>> +	media_entity_pipeline_stop(&vcap->vdev.entity);
>> +
>> +	/* Release all active buffers */
>> +	vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_ERROR);
>> +}
>> +
>> +static void vimc_cap_buf_queue(struct vb2_buffer *vb2_buf)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb2_buf->vb2_queue);
>> +	struct vimc_cap_buffer *buf = container_of(vb2_buf,
>> +						   struct vimc_cap_buffer,
>> +						   vb2.vb2_buf);
>> +
>> +	spin_lock(&vcap->qlock);
>> +	list_add_tail(&buf->list, &vcap->buf_list);
>> +	spin_unlock(&vcap->qlock);
>> +}
>> +
>> +static int vimc_cap_queue_setup(struct vb2_queue *vq, unsigned int
>> *nbuffers,
>> +				unsigned int *nplanes, unsigned int sizes[],
>> +				struct device *alloc_devs[])
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>> +
>> +	if (*nplanes)
>
> You should also return an error if *nplanes != 1 in this case.
>
>> +		return sizes[0] < vcap->format.sizeimage ? -EINVAL : 0;
>> +	/* We don't support multiplanes for now */
>> +	*nplanes = 1;
>> +	sizes[0] = vcap->format.sizeimage;
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Prepare the buffer for queueing to the DMA engine: check and set the
>
> There's no DMA engine, this is a virtual device :-)
>
>> + * payload size.
>> + */
>> +static int vimc_cap_buffer_prepare(struct vb2_buffer *vb)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb->vb2_queue);
>> +	unsigned long size = vcap->format.sizeimage;
>> +
>> +	if (vb2_plane_size(vb, 0) < size) {
>> +		dev_err(vcap->dev, "buffer too small (%lu < %lu)\n",
>> +			vb2_plane_size(vb, 0), size);
>> +		return -EINVAL;
>> +	}
>> +
>> +	vb2_set_plane_payload(vb, 0, size);
>
> If you call this here you don't have to duplicate the call in
> vimc_cap_process_frame(). I would keep the one in vimc_cap_process_frame() and
> remove this one.
>
>> +	return 0;
>> +}
>> +
>> +static const struct vb2_ops vimc_cap_qops = {
>> +	.start_streaming	= vimc_cap_start_streaming,
>> +	.stop_streaming		= vimc_cap_stop_streaming,
>> +	.buf_queue		= vimc_cap_buf_queue,
>> +	.queue_setup		= vimc_cap_queue_setup,
>> +	.buf_prepare		= vimc_cap_buffer_prepare,
>> +	/*
>> +	 * Since q->lock is set we can use the standard
>> +	 * vb2_ops_wait_prepare/finish helper functions.
>> +	 */
>> +	.wait_prepare		= vb2_ops_wait_prepare,
>> +	.wait_finish		= vb2_ops_wait_finish,
>> +};
>> +
>> +/* NOTE: this function is a copy of v4l2_subdev_link_validate_get_format
>> + * maybe the v4l2 function should be public
>> + */
>
> Or we should add a standard subdev <-> video devnode link validation function
> in the core :-) So far all drivers validate that link manually, but I don't
> remember a good reason why that couldn't be performed by the link validation
> infrastructure. Sakari, what do you think ?
>
> That's anyway not a blocker to get this patch merged.
>
>> +static int vimc_cap_v4l2_subdev_link_validate_get_format(struct media_pad
>> *pad,
>> +						struct v4l2_subdev_format
> *fmt)
>> +{
>> +	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(pad->entity);
>> +
>> +	fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
>> +	fmt->pad = pad->index;
>> +	return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);
>> +}
>> +
>> +static int vimc_cap_link_validate(struct media_link *link)
>> +{
>> +	struct v4l2_subdev_format source_fmt;
>> +	struct v4l2_pix_format *sink_fmt;
>> +	struct vimc_cap_device *vcap;
>> +	const struct vimc_pix_map *vpix;
>> +	int ret;
>> +
>> +	/* Retrieve the video capture device */
>> +	vcap = container_of(link->sink->entity,
>> +			    struct vimc_cap_device, vdev.entity);
>> +
>> +	/* If the connected node is not a subdevice type
>> +	 * then it's a raw node from vimc-core, ignore the link for now
>> +	 * TODO: remove this when there are no more raw nodes in the
>> +	 * core and return error instead
>> +	 */
>> +	if (!is_media_entity_v4l2_subdev(link->source->entity))
>> +		return 0;
>> +
>> +	/* Get the the format of the video device */
>> +	sink_fmt = &vcap->format;
>> +
>> +	/* Get the the format of the subdev */
>> +	ret = vimc_cap_v4l2_subdev_link_validate_get_format(link->source,
>> +							    &source_fmt);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_dbg(vcap->dev,
>> +		"cap: %s: link validate formats src:%dx%d %d sink:%dx%d %d\n",
>> +		vcap->vdev.name,
>> +		source_fmt.format.width, source_fmt.format.height,
>> +		source_fmt.format.code,
>> +		sink_fmt->width, sink_fmt->height,
>> +		sink_fmt->pixelformat);
>> +
>> +	/* Validate the format */
>> +
>> +	vpix = vimc_pix_map_by_pixelformat(sink_fmt->pixelformat);
>> +	if (!vpix)
>> +		return -EINVAL;
>
> This can't happen, it should be caught by the set format handler. The driver
> should not allowed the stored pixel format to ever be invalid.
>
>> +	/* The width, height and code must match. */
>> +	if (source_fmt.format.width != sink_fmt->width
>> +	    || source_fmt.format.height != sink_fmt->height
>> +	    || vpix->code != source_fmt.format.code)
>> +		return -EINVAL;
>> +
>> +	/* The field order must match, or the sink field order must be NONE
>> +	 * to support interlaced hardware connected to bridges that support
>> +	 * progressive formats only.
>> +	 */
>> +	if (source_fmt.format.field != sink_fmt->field &&
>> +	    sink_fmt->field != V4L2_FIELD_NONE)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>
> [snip]
>
>> +struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
>> +					const char *const name,
>> +					u16 num_pads,
>> +					const unsigned long *pads_flag)
>> +{
>> +	int ret;
>> +	struct vb2_queue *q;
>> +	struct video_device *vdev;
>> +	struct vimc_cap_device *vcap;
>> +	const struct vimc_pix_map *vpix;
>> +
>> +	/* Check entity configuration params
>> +	 * NOTE: we only support a single sink pad
>> +	 */
>> +	if (!name || num_pads != 1 || !pads_flag ||
>> +	    !(pads_flag[0] & MEDIA_PAD_FL_SINK))
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	/* Allocate the vimc_cap_device struct */
>> +	vcap = kzalloc(sizeof(*vcap), GFP_KERNEL);
>> +	if (!vcap)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* Link the vimc_cap_device struct with v4l2 and dev parent */
>> +	vcap->v4l2_dev = v4l2_dev;
>> +	vcap->dev = v4l2_dev->dev;
>> +
>> +	/* Allocate the pads */
>> +	vcap->ved.pads = vimc_pads_init(num_pads, pads_flag);
>> +	if (IS_ERR(vcap->ved.pads)) {
>> +		ret = PTR_ERR(vcap->ved.pads);
>> +		goto err_free_vcap;
>> +	}
>> +
>> +	/* Initialize the media entity */
>> +	vcap->vdev.entity.name = name;
>> +	vcap->vdev.entity.function = MEDIA_ENT_F_IO_V4L;
>> +	ret = media_entity_pads_init(&vcap->vdev.entity,
>> +				     num_pads, vcap->ved.pads);
>> +	if (ret)
>> +		goto err_clean_pads;
>> +
>> +	/* Initialize the lock */
>> +	mutex_init(&vcap->lock);
>> +
>> +	/* Initialize the vb2 queue */
>> +	q = &vcap->queue;
>> +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>> +	q->io_modes = VB2_MMAP | VB2_DMABUF;
>> +	q->drv_priv = vcap;
>> +	q->buf_struct_size = sizeof(struct vimc_cap_buffer);
>> +	q->ops = &vimc_cap_qops;
>> +	q->mem_ops = &vb2_vmalloc_memops;
>> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
>> +	q->min_buffers_needed = 2;
>> +	q->lock = &vcap->lock;
>> +
>> +	ret = vb2_queue_init(q);
>> +	if (ret) {
>> +		dev_err(vcap->dev,
>> +			"vb2 queue init failed (err=%d)\n", ret);
>> +		goto err_clean_m_ent;
>> +	}
>> +
>> +	/* Initialize buffer list and its lock */
>> +	INIT_LIST_HEAD(&vcap->buf_list);
>> +	spin_lock_init(&vcap->qlock);
>> +
>> +	/* Set the frame format (this is hardcoded for now) */
>> +	vcap->format.width = 640;
>> +	vcap->format.height = 480;
>> +	vcap->format.pixelformat = V4L2_PIX_FMT_RGB24;
>> +	vcap->format.field = V4L2_FIELD_NONE;
>> +	vcap->format.colorspace = V4L2_COLORSPACE_SRGB;
>> +
>> +	vpix = vimc_pix_map_by_pixelformat(vcap->format.pixelformat);
>> +
>> +	vcap->format.bytesperline = vcap->format.width * vpix->bpp;
>> +	vcap->format.sizeimage = vcap->format.bytesperline *
>> +				 vcap->format.height;
>> +
>> +	/* Fill the vimc_ent_device struct */
>> +	vcap->ved.destroy = vimc_cap_destroy;
>> +	vcap->ved.ent = &vcap->vdev.entity;
>> +	vcap->ved.process_frame = vimc_cap_process_frame;
>> +
>> +	/* Initialize the video_device struct */
>> +	vdev = &vcap->vdev;
>> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
>> +	vdev->entity.ops = &vimc_cap_mops;
>> +	vdev->release = video_device_release_empty;
>
> This will result in a crash if you keep the video device node open and unbind
> the vimc device from the driver. However, as the same issue in the media
> controller core hasn't been solved yet, I'm fine fixing all those problems in
> one go later.
>
>> +	vdev->fops = &vimc_cap_fops;
>> +	vdev->ioctl_ops = &vimc_cap_ioctl_ops;
>> +	vdev->lock = &vcap->lock;
>> +	vdev->queue = q;
>> +	vdev->v4l2_dev = vcap->v4l2_dev;
>> +	vdev->vfl_dir = VFL_DIR_RX;
>> +	strlcpy(vdev->name, name, sizeof(vdev->name));
>> +	video_set_drvdata(vdev, vcap);
>> +
>> +	/* Register the video_device with the v4l2 and the media framework */
>> +	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
>> +	if (ret) {
>> +		dev_err(vcap->dev,
>> +			"video register failed (err=%d)\n", ret);
>> +		goto err_release_queue;
>> +	}
>> +
>> +	return &vcap->ved;
>> +
>> +err_release_queue:
>> +	vb2_queue_release(q);
>> +err_clean_m_ent:
>> +	media_entity_cleanup(&vcap->vdev.entity);
>> +err_clean_pads:
>> +	vimc_pads_cleanup(vcap->ved.pads);
>> +err_free_vcap:
>> +	kfree(vcap);
>> +
>> +	return ERR_PTR(ret);
>> +}
>
> [snip]
>
>> diff --git a/drivers/media/platform/vimc/vimc-core.c
>> b/drivers/media/platform/vimc/vimc-core.c new file mode 100644
>> index 0000000..0a2b91b
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-core.c
>
> [snip]
>
>> +#define VIMC_ENT_LINK(src, srcpad, sink, sinkpad, link_flags) {	\
>> +	.src_ent = src,						\
>> +	.src_pad = srcpad,					\
>> +	.sink_ent = sink,					\
>> +	.sink_pad = sinkpad,					\
>> +	.flags = link_flags,					\
>> +}
>> +
>> +#define VIMC_PIX_MAP(_code, _bpp, _pixelformat) {	\
>> +	.code = _code,					\
>> +	.pixelformat = _pixelformat,			\
>> +	.bpp = _bpp,					\
>> +}
>> +
>> +struct vimc_device {
>> +	/* The pipeline configuration
>> +	 * (filled before calling vimc_device_register)
>> +	 */
>> +	const struct vimc_pipeline_config *pipe_cfg;
>> +
>> +	/* The Associated media_device parent */
>> +	struct media_device mdev;
>> +
>> +	/* Internal v4l2 parent device*/
>> +	struct v4l2_device v4l2_dev;
>> +
>> +	/* Internal topology */
>> +	struct vimc_ent_device **ved;
>> +};
>> +
>> +/**
>> + * enum vimc_ent_node - Select the functionality of a node in the topology
>> + * @VIMC_ENT_NODE_SENSOR:	A node of type SENSOR simulates a camera
> sensor
>> + *				generating internal images in bayer format and
>> + *				propagating those images through the pipeline
>> + * @VIMC_ENT_NODE_CAPTURE:	A node of type CAPTURE is a v4l2 video_device
>> + *				that exposes the received image from the
>> + *				pipeline to the user space
>> + * @VIMC_ENT_NODE_INPUT:	A node of type INPUT is a v4l2 video_device
> that
>> + *				receives images from the user space and
>> + *				propagates them through the pipeline
>> + * @VIMC_ENT_NODE_DEBAYER:	A node type DEBAYER expects to receive a frame
>> + *				in bayer format converts it to RGB
>> + * @VIMC_ENT_NODE_SCALER:	A node of type SCALER scales the received
> image
>> + *				by a given multiplier
>> + *
>> + * This enum is used in the entity configuration struct to allow the
>> definition + * of a custom topology specifying the role of each node on it.
>> + */
>> +enum vimc_ent_node {
>> +	VIMC_ENT_NODE_SENSOR,
>> +	VIMC_ENT_NODE_CAPTURE,
>> +	VIMC_ENT_NODE_INPUT,
>> +	VIMC_ENT_NODE_DEBAYER,
>> +	VIMC_ENT_NODE_SCALER,
>> +};
>> +
>> +/* Structure which describes individual configuration for each entity */
>> +struct vimc_ent_config {
>> +	const char *name;
>> +	size_t pads_qty;
>> +	const unsigned long *pads_flag;
>> +	enum vimc_ent_node node;
>> +};
>> +
>> +/* Structure which describes links between entities */
>> +struct vimc_ent_link {
>> +	unsigned int src_ent;
>> +	u16 src_pad;
>> +	unsigned int sink_ent;
>> +	u16 sink_pad;
>> +	u32 flags;
>> +};
>> +
>> +/* Structure which describes the whole topology */
>> +struct vimc_pipeline_config {
>> +	const struct vimc_ent_config *ents;
>> +	size_t num_ents;
>> +	const struct vimc_ent_link *links;
>> +	size_t num_links;
>> +};
>> +
>> +/*
>> --------------------------------------------------------------------------
>> + * Topology Configuration
>> + */
>> +
>> +static const struct vimc_ent_config ent_config[] = {
>> +	{
>> +		.name = "Sensor A",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_SENSOR,
>> +	},
>> +	{
>> +		.name = "Sensor B",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_SENSOR,
>> +	},
>> +	{
>> +		.name = "Debayer A",
>> +		.pads_qty = 2,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
>> +						     MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_DEBAYER,
>> +	},
>> +	{
>> +		.name = "Debayer B",
>> +		.pads_qty = 2,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
>> +						     MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_DEBAYER,
>> +	},
>> +	{
>> +		.name = "Raw Capture 0",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
>> +		.node = VIMC_ENT_NODE_CAPTURE,
>> +	},
>> +	{
>> +		.name = "Raw Capture 1",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
>> +		.node = VIMC_ENT_NODE_CAPTURE,
>> +	},
>> +	{
>> +		.name = "RGB/YUV Input",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_INPUT,
>> +	},
>> +	{
>> +		.name = "Scaler",
>> +		.pads_qty = 2,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
>> +						     MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_SCALER,
>> +	},
>> +	{
>> +		.name = "RGB/YUV Capture",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
>> +		.node = VIMC_ENT_NODE_CAPTURE,
>> +	},
>> +};
>> +
>> +static const struct vimc_ent_link ent_links[] = {
>> +	/* Link: Sensor A (Pad 0)->(Pad 0) Debayer A */
>> +	VIMC_ENT_LINK(0, 0, 2, 0, MEDIA_LNK_FL_ENABLED |
> MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Sensor A (Pad 0)->(Pad 0) Raw Capture 0 */
>> +	VIMC_ENT_LINK(0, 0, 4, 0, MEDIA_LNK_FL_ENABLED |
> MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Sensor B (Pad 0)->(Pad 0) Debayer B */
>> +	VIMC_ENT_LINK(1, 0, 3, 0, MEDIA_LNK_FL_ENABLED |
> MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Sensor B (Pad 0)->(Pad 0) Raw Capture 1 */
>> +	VIMC_ENT_LINK(1, 0, 5, 0, MEDIA_LNK_FL_ENABLED |
> MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Debayer A (Pad 1)->(Pad 0) Scaler */
>> +	VIMC_ENT_LINK(2, 1, 7, 0, MEDIA_LNK_FL_ENABLED),
>> +	/* Link: Debayer B (Pad 1)->(Pad 0) Scaler */
>> +	VIMC_ENT_LINK(3, 1, 7, 0, 0),
>> +	/* Link: RGB/YUV Input (Pad 0)->(Pad 0) Scaler */
>> +	VIMC_ENT_LINK(6, 0, 7, 0, 0),
>> +	/* Link: Scaler (Pad 1)->(Pad 0) RGB/YUV Capture */
>> +	VIMC_ENT_LINK(7, 1, 8, 0, MEDIA_LNK_FL_ENABLED |
> MEDIA_LNK_FL_IMMUTABLE),
>> +};
>> +
>> +static const struct vimc_pipeline_config pipe_cfg = {
>> +	.ents		= ent_config,
>> +	.num_ents	= ARRAY_SIZE(ent_config),
>> +	.links		= ent_links,
>> +	.num_links	= ARRAY_SIZE(ent_links)
>> +};
>> +
>> +/* --------------------------------------------------------------------- */
>> +
>> +static void vimc_dev_release(struct device *dev)
>> +{}
>
> Missing line break between the braces.
>
>> +
>> +static struct platform_device vimc_pdev = {
>> +	.name		= VIMC_PDEV_NAME,
>> +	.dev.release	= vimc_dev_release,
>> +};
>> +
>> +const struct vimc_pix_map vimc_pix_map_list[] = {
>
> This array isn't used outside of the compilation unit, you can make it static.
>
>> +	/* TODO: add all missing formats */
>> +
>> +	/* RGB formats */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_BGR888_1X24, 3, V4L2_PIX_FMT_BGR24),
>
> Is there really an added value in using the macro compared to direct array
> initialization ?
>
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_RGB888_1X24, 3, V4L2_PIX_FMT_RGB24),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_ARGB8888_1X32, 4, V4L2_PIX_FMT_ARGB32),
>> +
>> +	/* Bayer formats */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR8_1X8, 1, V4L2_PIX_FMT_SBGGR8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG8_1X8, 1, V4L2_PIX_FMT_SGBRG8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG8_1X8, 1, V4L2_PIX_FMT_SGRBG8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB8_1X8, 1, V4L2_PIX_FMT_SRGGB8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_1X10, 2, V4L2_PIX_FMT_SBGGR10),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_1X10, 2, V4L2_PIX_FMT_SGBRG10),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_1X10, 2, V4L2_PIX_FMT_SGRBG10),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_1X10, 2, V4L2_PIX_FMT_SRGGB10),
>> +	/* 10bit raw bayer a-law compressed to 8 bits */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_ALAW8_1X8, 1,
>> V4L2_PIX_FMT_SBGGR10ALAW8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_ALAW8_1X8, 1,
>> V4L2_PIX_FMT_SGBRG10ALAW8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_ALAW8_1X8, 1,
>> V4L2_PIX_FMT_SGRBG10ALAW8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_ALAW8_1X8, 1,
>> V4L2_PIX_FMT_SRGGB10ALAW8),
>> +	/* 10bit raw bayer DPCM compressed to 8 bits */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_DPCM8_1X8, 1,
>> V4L2_PIX_FMT_SBGGR10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_DPCM8_1X8, 1,
>> V4L2_PIX_FMT_SGBRG10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_DPCM8_1X8, 1,
>> V4L2_PIX_FMT_SGRBG10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_DPCM8_1X8, 1,
> V4L2_PIX_FMT_SRGGB10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR12_1X12, 2, V4L2_PIX_FMT_SBGGR12),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG12_1X12, 2, V4L2_PIX_FMT_SGBRG12),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG12_1X12, 2, V4L2_PIX_FMT_SGRBG12),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB12_1X12, 2, V4L2_PIX_FMT_SRGGB12),
>> +
>> +	/* End */
>> +	{0, 0, 0}
>> +};
>> +
>> +const struct vimc_pix_map *vimc_pix_map_by_code(u32 code)
>> +{
>> +	unsigned int i;
>> +
>> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
>
> You can use i < ARRAY_SIZE(vimc_pix_map_list) as the condition here and in the
> function below, and get rid of the termination marker in the array.
>
>> +		if (vimc_pix_map_list[i].code == code)
>> +			return &vimc_pix_map_list[i];
>> +	}
>> +	return NULL;
>> +}
>> +
>> +const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat)
>> +{
>> +	unsigned int i;
>> +
>> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
>> +		if (vimc_pix_map_list[i].pixelformat == pixelformat)
>> +			return &vimc_pix_map_list[i];
>> +	}
>> +	return NULL;
>> +}
>
> [snip]
>
>> +/* TODO: remove this function when all the
>> + * entities specific code are implemented
>> + */
>> +static struct vimc_ent_device *vimc_raw_create(struct v4l2_device
>> *v4l2_dev,
>> +					       const char *const name,
>> +					       u16 num_pads,
>> +					       const unsigned long *pads_flag)
>> +{
>> +	int ret;
>> +	struct vimc_ent_device *ved;
>> +
>> +	/* Allocate the main ved struct */
>> +	ved = kzalloc(sizeof(*ved), GFP_KERNEL);
>> +	if (!ved)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* Allocate the media entity */
>> +	ved->ent = kzalloc(sizeof(*ved->ent), GFP_KERNEL);
>> +	if (!ved->ent) {
>> +		ret = -ENOMEM;
>> +		goto err_free_ved;
>> +	}
>> +
>> +	/* Allocate the pads */
>> +	ved->pads = vimc_pads_init(num_pads, pads_flag);
>> +	if (IS_ERR(ved->pads)) {
>> +		ret = PTR_ERR(ved->pads);
>> +		goto err_free_ent;
>> +	}
>> +
>> +	/* Initialize the media entity */
>> +	ved->ent->name = name;
>> +	ved->ent->function = MEDIA_ENT_F_IO_V4L;
>
> This isn't a video node. You can use MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN for now.
>
>> +	ret = media_entity_pads_init(ved->ent, num_pads, ved->pads);
>> +	if (ret)
>> +		goto err_cleanup_pads;
>> +
>> +	/* Register the media entity */
>> +	ret = media_device_register_entity(v4l2_dev->mdev, ved->ent);
>> +	if (ret)
>> +		goto err_cleanup_entity;
>> +
>> +	/* Fill out the destroy function and return */
>> +	ved->destroy = vimc_raw_destroy;
>> +	return ved;
>> +
>> +err_cleanup_entity:
>> +	media_entity_cleanup(ved->ent);
>> +err_cleanup_pads:
>> +	vimc_pads_cleanup(ved->pads);
>> +err_free_ent:
>> +	kfree(ved->ent);
>> +err_free_ved:
>> +	kfree(ved);
>> +
>> +	return ERR_PTR(ret);
>> +}
>> +
>> +static int vimc_device_register(struct vimc_device *vimc)
>> +{
>> +	unsigned int i;
>> +	int ret = 0;
>
> There's no need to assign 0 to ret here.
>
>> +	/* Allocate memory for the vimc_ent_devices pointers */
>> +	vimc->ved = devm_kcalloc(vimc->mdev.dev, vimc->pipe_cfg->num_ents,
>> +				 sizeof(*vimc->ved), GFP_KERNEL);
>> +	if (!vimc->ved)
>> +		return -ENOMEM;
>> +
>> +	/* Register the media device */
>> +	ret = media_device_register(&vimc->mdev);
>
> Shouldn't you register the media device after creating the entities and links
> ?
>
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"media device register failed (err=%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Link the media device within the v4l2_device */
>> +	vimc->v4l2_dev.mdev = &vimc->mdev;
>> +
>> +	/* Register the v4l2 struct */
>> +	ret = v4l2_device_register(vimc->mdev.dev, &vimc->v4l2_dev);
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"v4l2 device register failed (err=%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Initialize entities */
>> +	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
>> +		struct vimc_ent_device *(*create_func)(struct v4l2_device *,
>> +						       const char *const,
>> +						       u16,
>> +						       const unsigned long *);
>> +
>> +		/* Register the specific node */
>> +		switch (vimc->pipe_cfg->ents[i].node) {
>> +		case VIMC_ENT_NODE_SENSOR:
>> +			create_func = vimc_sen_create;
>> +			break;
>> +
>> +		case VIMC_ENT_NODE_CAPTURE:
>> +			create_func = vimc_cap_create;
>> +			break;
>> +
>> +		/* TODO: Instantiate the specific topology node */
>> +		case VIMC_ENT_NODE_INPUT:
>> +		case VIMC_ENT_NODE_DEBAYER:
>> +		case VIMC_ENT_NODE_SCALER:
>> +		default:
>> +			/* TODO: remove this when all the entities specific
>> +			 * code are implemented
>> +			 */
>> +			create_func = vimc_raw_create;
>> +			break;
>> +		}
>> +
>> +		vimc->ved[i] = create_func(&vimc->v4l2_dev,
>> +					   vimc->pipe_cfg->ents[i].name,
>> +					   vimc->pipe_cfg->ents[i].pads_qty,
>> +					   vimc->pipe_cfg->ents[i].pads_flag);
>> +		if (IS_ERR(vimc->ved[i])) {
>> +			ret = PTR_ERR(vimc->ved[i]);
>> +			vimc->ved[i] = NULL;
>> +			goto err;
>> +		}
>> +
>> +		/* Set use_count to keep track of the ved structure */
>> +		vimc->ved[i]->ent->use_count = i;
>
> The media_entity::use_count field is managed by the media controller core. You
> can't use it for your own purpose.
>
>> +	}
>> +
>> +	/* Initialize the links between entities */
>> +	for (i = 0; i < vimc->pipe_cfg->num_links; i++) {
>> +		const struct vimc_ent_link *link = &vimc->pipe_cfg->links[i];
>> +
>> +		ret = media_create_pad_link(vimc->ved[link->src_ent]->ent,
>> +					    link->src_pad,
>> +					    vimc->ved[link->sink_ent]->ent,
>> +					    link->sink_pad,
>> +					    link->flags);
>> +		if (ret)
>> +			goto err;
>> +	}
>> +
>> +	/* Expose all subdev's nodes*/
>> +	ret = v4l2_device_register_subdev_nodes(&vimc->v4l2_dev);
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"vimc subdev nodes registration failed (err=%d)\n",
>> +			ret);
>> +		goto err;
>> +	}
>> +
>> +	return 0;
>> +
>> +err:
>> +	/* Destroy the so far created topology */
>> +	vimc_device_unregister(vimc);
>> +
>> +	return ret;
>> +}
>> +
>> +static int vimc_probe(struct platform_device *pdev)
>> +{
>> +	struct vimc_device *vimc;
>> +	int ret;
>> +
>> +	/* Prepare the vimc topology structure */
>> +
>> +	/* Allocate memory for the vimc structure */
>> +	vimc = devm_kzalloc(&pdev->dev, sizeof(*vimc), GFP_KERNEL);
>> +	if (!vimc)
>> +		return -ENOMEM;
>
> We have recently come to an agreement that devm_kzalloc() is harmful to
> allocate structures that embed instances of struct media_device. While this is
> still an unresolved problem, could you please use kzalloc() to avoid making it
> worse ? It will require a kfree() in the error paths and in the remove
> handler.
>
>> +	/* Set the pipeline configuration struct */
>> +	vimc->pipe_cfg = &pipe_cfg;
>> +
>> +	/* Initialize media device */
>> +	strlcpy(vimc->mdev.model, VIMC_MDEV_MODEL_NAME,
>> +		sizeof(vimc->mdev.model));
>> +	vimc->mdev.dev = &pdev->dev;
>> +	media_device_init(&vimc->mdev);
>> +
>> +	/* Create vimc topology */
>> +	ret = vimc_device_register(vimc);
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"vimc device registration failed (err=%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Link the topology object with the platform device object */
>> +	platform_set_drvdata(pdev, vimc);
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_remove(struct platform_device *pdev)
>> +{
>> +	struct vimc_device *vimc;
>> +
>> +	/* Get the topology object linked with the platform device object */
>> +	vimc = platform_get_drvdata(pdev);
>
> You could combine that in a single line
>
> 	struct vimc_device *vimc = platform_get_drvdata(pdev);
>
> I understand that the comment was written when you had less experience with
> the kernel code which pushed you on the side of verbosity, but I believe it's
> not really needed :-)
>
>> +
>> +	/* Destroy all the topology */
>> +	vimc_device_unregister(vimc);
>> +
>> +	return 0;
>> +}
>
> [snip]
>
>> diff --git a/drivers/media/platform/vimc/vimc-sensor.c
>> b/drivers/media/platform/vimc/vimc-sensor.c new file mode 100644
>> index 0000000..174e5dc
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-sensor.c
>
> [snip]
>
>> +static int vimc_thread_sen(void *data)
>> +{
>> +	unsigned int i;
>> +	struct vimc_sen_device *vsen = data;
>> +
>> +	set_freezable();
>> +
>> +	for (;;) {
>> +		try_to_freeze();
>> +		if (kthread_should_stop())
>> +			break;
>> +
>> +		memset(vsen->frame, 100, vsen->frame_size);
>> +
>> +		/* Send the frame to all source pads */
>> +		for (i = 0; i < vsen->sd.entity.num_pads; i++)
>> +			vimc_propagate_frame(vsen->dev,
>> +					     &vsen->sd.entity.pads[i],
>> +					     vsen->frame);
>> +
>> +		/* 60 frames per second */
>> +		schedule_timeout_interruptible(HZ/60);
>
> What can this be interrupted by ?
>
>> +	}
>> +
>> +	return 0;
>> +}
>
> [snip]
>
>> +struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
>> +					const char *const name,
>> +					u16 num_pads,
>> +					const unsigned long *pads_flag)
>> +{
>> +	int ret;
>> +	unsigned int i;
>> +	struct vimc_sen_device *vsen;
>> +
>> +	if (!name || (num_pads && !pads_flag))
>> +		return ERR_PTR(-EINVAL);
>
> I think you need at least one pad. Or actually, exactly one pad.
>
>> +	/* check if all pads are sources */
>> +	for (i = 0; i < num_pads; i++)
>> +		if (!(pads_flag[i] & MEDIA_PAD_FL_SOURCE))
>> +			return ERR_PTR(-EINVAL);
>> +
>> +	/* Allocate the vsen struct */
>> +	vsen = kzalloc(sizeof(*vsen), GFP_KERNEL);
>> +	if (!vsen)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* Link the vimc_sen_device struct with the v4l2 parent */
>> +	vsen->v4l2_dev = v4l2_dev;
>> +	/* Link the vimc_sen_device struct with the dev parent */
>> +	vsen->dev = v4l2_dev->dev;
>> +
>> +	/* Allocate the pads */
>> +	vsen->ved.pads = vimc_pads_init(num_pads, pads_flag);
>> +	if (IS_ERR(vsen->ved.pads)) {
>> +		ret = PTR_ERR(vsen->ved.pads);
>> +		goto err_free_vsen;
>> +	}
>> +
>> +	/* Initialize the media entity */
>> +	vsen->sd.entity.name = name;
>> +	ret = media_entity_pads_init(&vsen->sd.entity,
>> +				     num_pads, vsen->ved.pads);
>> +	if (ret)
>> +		goto err_clean_pads;
>> +
>> +	/* Set the active frame format (this is hardcoded for now) */
>> +	vsen->mbus_format.width = 640;
>> +	vsen->mbus_format.height = 480;
>> +	vsen->mbus_format.code = MEDIA_BUS_FMT_RGB888_1X24;
>> +	vsen->mbus_format.field = V4L2_FIELD_NONE;
>> +	vsen->mbus_format.colorspace = V4L2_COLORSPACE_SRGB;
>> +	vsen->mbus_format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
>> +	vsen->mbus_format.xfer_func = V4L2_XFER_FUNC_SRGB;
>> +
>> +	/* Fill the vimc_ent_device struct */
>> +	vsen->ved.destroy = vimc_sen_destroy;
>> +	vsen->ved.ent = &vsen->sd.entity;
>> +
>> +	/* Initialize the subdev */
>> +	v4l2_subdev_init(&vsen->sd, &vimc_sen_ops);
>> +	vsen->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
>> +	vsen->sd.entity.ops = &vimc_sen_mops;
>> +	vsen->sd.owner = THIS_MODULE;
>> +	strlcpy(vsen->sd.name, name, sizeof(vsen->sd.name));
>> +	v4l2_set_subdevdata(&vsen->sd, vsen);
>> +
>> +	/* Expose this subdev to user space */
>> +	vsen->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
>> +
>> +	/* Register the subdev with the v4l2 and the media framework */
>> +	ret = v4l2_device_register_subdev(vsen->v4l2_dev, &vsen->sd);
>> +	if (ret) {
>> +		dev_err(vsen->dev,
>> +			"subdev register failed (err=%d)\n", ret);
>> +		goto err_clean_m_ent;
>> +	}
>> +
>> +	return &vsen->ved;
>> +
>> +err_clean_m_ent:
>> +	media_entity_cleanup(&vsen->sd.entity);
>> +err_clean_pads:
>> +	vimc_pads_cleanup(vsen->ved.pads);
>> +err_free_vsen:
>> +	kfree(vsen);
>> +
>> +	return ERR_PTR(ret);
>> +}
>
> [snip]
>

Thank you for the review, I'll update the patch accordingly and 
re-submit it.

Helen
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Sakari Ailus Jan. 25, 2017, 1:03 p.m. UTC | #4
Hi Helen,

My apologies for the long review time!

Please see my comments below.

On Sun, Sep 04, 2016 at 05:02:18PM -0300, Helen Koike wrote:
> From: Helen Fornazier <helen.fornazier@gmail.com>
> 
> First version of the Virtual Media Controller.
> Add a simple version of the core of the driver, the capture and
> sensor nodes in the topology, generating a grey image in a hardcoded
> format.
> 
> Signed-off-by: Helen Koike <helen.koike@collabora.com>
> 
> ---
> 
> Patch based in media/master tree, and available here:
> https://github.com/helen-fornazier/opw-staging/tree/vimc/devel/vpu
> 
> Changes since v5:
> - Fix message "Entity type for entity Sensor A was not initialized!"
>   by initializing the sensor entity.function after the calling
>   v4l2_subded_init
> - populate device_caps in vimc_cap_create instead of in
>   vimc_cap_querycap
> - Fix typo in vimc-core.c s/de/the
> 
> Changes since v4:
> - coding style fixes
> - remove BUG_ON
> - change copyright to 2016
> - depens on VIDEO_V4L2_SUBDEV_API instead of select
> - remove assignement of V4L2_CAP_DEVICE_CAPS
> - s/vimc_cap_g_fmt_vid_cap/vimc_cap_fmt_vid_cap
> - fix vimc_cap_queue_setup declaration type
> - remove wrong buffer size check and add it in vimc_cap_buffer_prepare
> - vimc_cap_create: remove unecessary check if v4l2_dev or v4l2_dev->dev is null
> - vimc_cap_create: only allow a single pad
> - vimc_sen_create: only allow source pads, remove unecessary source pads
> checks in vimc_thread_sen
> 
> Changes since v3: fix rmmod crash and built-in compile
> - Re-order unregister calls in vimc_device_unregister function (remove
> rmmod issue)
> - Call media_device_unregister_entity in vimc_raw_destroy
> - Add depends on VIDEO_DEV && VIDEO_V4L2 and select VIDEOBUF2_VMALLOC
> - Check *nplanes in queue_setup (this remove v4l2-compliance fail)
> - Include <linux/kthread.h> in vimc-sensor.c
> - Move include of <linux/slab.h> from vimc-core.c to vimc-core.h
> - Generate 60 frames per sec instead of 1 in the sensor
> 
> Changes since v2: update with current media master tree
> - Add struct media_pipeline in vimc_cap_device
> - Use vb2_v4l2_buffer instead of vb2_buffer
> - Typos
> - Remove usage of entity->type and use entity->function instead
> - Remove fmt argument from queue setup
> - Use ktime_get_ns instead of v4l2_get_timestamp
> - Iterate over link's list using list_for_each_entry
> - Use media_device_{init, cleanup}
> - Use entity->use_count to keep track of entities instead of the old
> entity->id
> - Replace media_entity_init by media_entity_pads_init
> ---
>  drivers/media/platform/Kconfig             |   2 +
>  drivers/media/platform/Makefile            |   1 +
>  drivers/media/platform/vimc/Kconfig        |   7 +
>  drivers/media/platform/vimc/Makefile       |   3 +
>  drivers/media/platform/vimc/vimc-capture.c | 553 ++++++++++++++++++++++++++
>  drivers/media/platform/vimc/vimc-capture.h |  28 ++
>  drivers/media/platform/vimc/vimc-core.c    | 600 +++++++++++++++++++++++++++++
>  drivers/media/platform/vimc/vimc-core.h    |  57 +++
>  drivers/media/platform/vimc/vimc-sensor.c  | 279 ++++++++++++++
>  drivers/media/platform/vimc/vimc-sensor.h  |  28 ++
>  10 files changed, 1558 insertions(+)
>  create mode 100644 drivers/media/platform/vimc/Kconfig
>  create mode 100644 drivers/media/platform/vimc/Makefile
>  create mode 100644 drivers/media/platform/vimc/vimc-capture.c
>  create mode 100644 drivers/media/platform/vimc/vimc-capture.h
>  create mode 100644 drivers/media/platform/vimc/vimc-core.c
>  create mode 100644 drivers/media/platform/vimc/vimc-core.h
>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.c
>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.h
> 
> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
> index 46f14dd..4a0577f 100644
> --- a/drivers/media/platform/Kconfig
> +++ b/drivers/media/platform/Kconfig
> @@ -329,6 +329,8 @@ menuconfig V4L_TEST_DRIVERS
>  
>  if V4L_TEST_DRIVERS
>  
> +source "drivers/media/platform/vimc/Kconfig"
> +
>  source "drivers/media/platform/vivid/Kconfig"
>  
>  config VIDEO_VIM2M
> diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
> index 536d1d8..dd4f658 100644
> --- a/drivers/media/platform/Makefile
> +++ b/drivers/media/platform/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_VIDEO_OMAP3)	+= omap3isp/
>  
>  obj-$(CONFIG_VIDEO_VIU) += fsl-viu.o
>  
> +obj-$(CONFIG_VIDEO_VIMC)		+= vimc/
>  obj-$(CONFIG_VIDEO_VIVID)		+= vivid/
>  obj-$(CONFIG_VIDEO_VIM2M)		+= vim2m.o
>  
> diff --git a/drivers/media/platform/vimc/Kconfig b/drivers/media/platform/vimc/Kconfig
> new file mode 100644
> index 0000000..b48819c
> --- /dev/null
> +++ b/drivers/media/platform/vimc/Kconfig
> @@ -0,0 +1,7 @@
> +config VIDEO_VIMC
> +	tristate "Virtual Media Controller Driver (VIMC)"
> +	depends on VIDEO_DEV && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
> +	select VIDEOBUF2_VMALLOC
> +	default n
> +	---help---
> +	  Skeleton driver for Virtual Media Controller

A bit more verbose description would be nice.

> diff --git a/drivers/media/platform/vimc/Makefile b/drivers/media/platform/vimc/Makefile
> new file mode 100644
> index 0000000..c45195e
> --- /dev/null
> +++ b/drivers/media/platform/vimc/Makefile
> @@ -0,0 +1,3 @@
> +vimc-objs := vimc-core.o vimc-capture.o vimc-sensor.o
> +
> +obj-$(CONFIG_VIDEO_VIMC) += vimc.o
> diff --git a/drivers/media/platform/vimc/vimc-capture.c b/drivers/media/platform/vimc/vimc-capture.c
> new file mode 100644
> index 0000000..b7636cf
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-capture.c
> @@ -0,0 +1,553 @@
> +/*
> + * vimc-capture.c Virtual Media Controller Driver
> + *
> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>

2017 might be used now.

> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <media/videobuf2-core.h>
> +#include <media/videobuf2-vmalloc.h>
> +#include <media/v4l2-ioctl.h>

Numbers come before letters.

> +
> +#include "vimc-capture.h"
> +
> +struct vimc_cap_device {
> +	struct vimc_ent_device ved;
> +	struct video_device vdev;
> +	struct v4l2_device *v4l2_dev;

struct video_device also has a pointer to v4l2_dev. I wonder if that could
be used.

> +	struct device *dev;
> +	struct v4l2_pix_format format;
> +	struct vb2_queue queue;
> +	struct list_head buf_list;
> +	/*
> +	 * NOTE: in a real driver, a spin lock must be used to access the
> +	 * queue because the frames are generated from a hardware interruption
> +	 * and the isr is not allowed to sleep.
> +	 * Even if it is not necessary a spinlock in the vimc driver, we
> +	 * use it here as a code reference
> +	 */
> +	spinlock_t qlock;
> +	struct mutex lock;
> +	u32 sequence;
> +	struct media_pipeline pipe;
> +};
> +
> +struct vimc_cap_buffer {
> +	/*
> +	 * vb2_buffer must be the first element

vb2 or struct vb2_v4l2_buffer ?

> +	 * the videobuf2 framework will allocate this struct based on
> +	 * buf_struct_size and use the first sizeof(struct vb2_buffer) bytes of
> +	 * memory as a vb2_buffer
> +	 */
> +	struct vb2_v4l2_buffer vb2;
> +	struct list_head list;
> +};
> +
> +static int vimc_cap_querycap(struct file *file, void *priv,
> +			     struct v4l2_capability *cap)
> +{
> +	struct vimc_cap_device *vcap = video_drvdata(file);
> +
> +	strlcpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
> +	strlcpy(cap->card, KBUILD_MODNAME, sizeof(cap->card));
> +	snprintf(cap->bus_info, sizeof(cap->bus_info),
> +		 "platform:%s", vcap->v4l2_dev->name);
> +
> +	return 0;
> +}
> +
> +static int vimc_cap_enum_input(struct file *file, void *priv,
> +			       struct v4l2_input *i)
> +{
> +	/* We only have one input */
> +	if (i->index > 0)
> +		return -EINVAL;
> +
> +	i->type = V4L2_INPUT_TYPE_CAMERA;
> +	strlcpy(i->name, "VIMC capture", sizeof(i->name));

Isn't this (*INPUT IOCTLs) something that should be handled in a sub-device
driver, such as a TV tuner?

> +
> +	return 0;
> +}
> +
> +static int vimc_cap_g_input(struct file *file, void *priv, unsigned int *i)
> +{
> +	/* We only have one input */
> +	*i = 0;
> +	return 0;
> +}
> +
> +static int vimc_cap_s_input(struct file *file, void *priv, unsigned int i)
> +{
> +	/* We only have one input */
> +	return i ? -EINVAL : 0;
> +}
> +
> +static int vimc_cap_fmt_vid_cap(struct file *file, void *priv,
> +				  struct v4l2_format *f)
> +{
> +	struct vimc_cap_device *vcap = video_drvdata(file);
> +
> +	f->fmt.pix = vcap->format;
> +
> +	return 0;
> +}
> +
> +static int vimc_cap_enum_fmt_vid_cap(struct file *file, void *priv,
> +				     struct v4l2_fmtdesc *f)
> +{
> +	struct vimc_cap_device *vcap = video_drvdata(file);
> +
> +	if (f->index > 0)
> +		return -EINVAL;
> +
> +	/* We only support one format for now */
> +	f->pixelformat = vcap->format.pixelformat;
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_file_operations vimc_cap_fops = {
> +	.owner		= THIS_MODULE,
> +	.open		= v4l2_fh_open,
> +	.release	= vb2_fop_release,
> +	.read           = vb2_fop_read,
> +	.poll		= vb2_fop_poll,
> +	.unlocked_ioctl = video_ioctl2,
> +	.mmap           = vb2_fop_mmap,
> +};
> +
> +static const struct v4l2_ioctl_ops vimc_cap_ioctl_ops = {
> +	.vidioc_querycap = vimc_cap_querycap,
> +
> +	.vidioc_enum_input = vimc_cap_enum_input,
> +	.vidioc_g_input = vimc_cap_g_input,
> +	.vidioc_s_input = vimc_cap_s_input,
> +
> +	.vidioc_g_fmt_vid_cap = vimc_cap_fmt_vid_cap,
> +	.vidioc_s_fmt_vid_cap = vimc_cap_fmt_vid_cap,
> +	.vidioc_try_fmt_vid_cap = vimc_cap_fmt_vid_cap,
> +	.vidioc_enum_fmt_vid_cap = vimc_cap_enum_fmt_vid_cap,
> +
> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
> +	.vidioc_querybuf = vb2_ioctl_querybuf,
> +	.vidioc_qbuf = vb2_ioctl_qbuf,
> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
> +	.vidioc_expbuf = vb2_ioctl_expbuf,
> +	.vidioc_streamon = vb2_ioctl_streamon,
> +	.vidioc_streamoff = vb2_ioctl_streamoff,
> +};
> +
> +static void vimc_cap_return_all_buffers(struct vimc_cap_device *vcap,
> +					enum vb2_buffer_state state)
> +{
> +	struct vimc_cap_buffer *vbuf, *node;
> +
> +	spin_lock(&vcap->qlock);
> +
> +	list_for_each_entry_safe(vbuf, node, &vcap->buf_list, list) {
> +		vb2_buffer_done(&vbuf->vb2.vb2_buf, state);
> +		list_del(&vbuf->list);
> +	}
> +
> +	spin_unlock(&vcap->qlock);
> +}
> +
> +static int vimc_cap_pipeline_s_stream(struct vimc_cap_device *vcap, int enable)
> +{
> +	int ret;
> +	struct media_pad *pad;
> +	struct media_entity *entity;
> +	struct v4l2_subdev *sd;
> +
> +	/* Start the stream in the subdevice direct connected */
> +	entity = &vcap->vdev.entity;
> +	pad = media_entity_remote_pad(&entity->pads[0]);

You could use vcap->vdev.entity.pads here, without assigning to entity. Then
entity would only be used to refer to the remove entity at the other end of
the link. Up to you.

> +
> +	/* If we are not connected to any subdev node, it means there is nothing

/*
 * Multi line
 * comment.
 */

> +	 * to activate on the pipe (e.g. we can be connected with an input
> +	 * device or we are not connected at all)
> +	 */
> +	if (pad == NULL || !is_media_entity_v4l2_subdev(pad->entity))
> +		return 0;
> +
> +	entity = pad->entity;
> +	sd = media_entity_to_v4l2_subdev(entity);

And if you used pad->entity here, you could remove the entity variable
altogether.

> +
> +	ret = v4l2_subdev_call(sd, video, s_stream, enable);
> +	if (ret && ret != -ENOIOCTLCMD)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int count)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> +	struct media_entity *entity;
> +	int ret;
> +
> +	vcap->sequence = 0;
> +
> +	/* Start the media pipeline */
> +	entity = &vcap->vdev.entity;
> +	ret = media_entity_pipeline_start(entity, &vcap->pipe);
> +	if (ret) {
> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
> +		return ret;
> +	}
> +
> +	/* Enable streaming from the pipe */
> +	ret = vimc_cap_pipeline_s_stream(vcap, 1);
> +	if (ret) {
> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Stop the stream engine. Any remaining buffers in the stream queue are
> + * dequeued and passed on to the vb2 framework marked as STATE_ERROR.
> + */
> +static void vimc_cap_stop_streaming(struct vb2_queue *vq)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> +
> +	/* Disable streaming from the pipe */
> +	vimc_cap_pipeline_s_stream(vcap, 0);
> +
> +	/* Stop the media pipeline */
> +	media_entity_pipeline_stop(&vcap->vdev.entity);
> +
> +	/* Release all active buffers */
> +	vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_ERROR);
> +}
> +
> +static void vimc_cap_buf_queue(struct vb2_buffer *vb2_buf)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb2_buf->vb2_queue);
> +	struct vimc_cap_buffer *buf = container_of(vb2_buf,
> +						   struct vimc_cap_buffer,
> +						   vb2.vb2_buf);
> +
> +	spin_lock(&vcap->qlock);
> +	list_add_tail(&buf->list, &vcap->buf_list);
> +	spin_unlock(&vcap->qlock);
> +}
> +
> +static int vimc_cap_queue_setup(struct vb2_queue *vq, unsigned int *nbuffers,
> +				unsigned int *nplanes, unsigned int sizes[],
> +				struct device *alloc_devs[])
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
> +
> +	if (*nplanes)
> +		return sizes[0] < vcap->format.sizeimage ? -EINVAL : 0;

Why? The user could later reconfigure the device to use with a buffer of
this size. This might not be a concern for vimc, but the code from example
drivers tends to get copied around.

> +	/* We don't support multiplanes for now */
> +	*nplanes = 1;
> +	sizes[0] = vcap->format.sizeimage;
> +
> +	return 0;
> +}
> +
> +/*
> + * Prepare the buffer for queueing to the DMA engine: check and set the
> + * payload size.
> + */
> +static int vimc_cap_buffer_prepare(struct vb2_buffer *vb)
> +{
> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb->vb2_queue);
> +	unsigned long size = vcap->format.sizeimage;
> +
> +	if (vb2_plane_size(vb, 0) < size) {
> +		dev_err(vcap->dev, "buffer too small (%lu < %lu)\n",
> +			vb2_plane_size(vb, 0), size);
> +		return -EINVAL;
> +	}
> +
> +	vb2_set_plane_payload(vb, 0, size);

Newline here?

> +	return 0;
> +}
> +
> +static const struct vb2_ops vimc_cap_qops = {
> +	.start_streaming	= vimc_cap_start_streaming,
> +	.stop_streaming		= vimc_cap_stop_streaming,
> +	.buf_queue		= vimc_cap_buf_queue,
> +	.queue_setup		= vimc_cap_queue_setup,
> +	.buf_prepare		= vimc_cap_buffer_prepare,
> +	/*
> +	 * Since q->lock is set we can use the standard
> +	 * vb2_ops_wait_prepare/finish helper functions.
> +	 */
> +	.wait_prepare		= vb2_ops_wait_prepare,
> +	.wait_finish		= vb2_ops_wait_finish,
> +};
> +

> +/* NOTE: this function is a copy of v4l2_subdev_link_validate_get_format

/*
 * ...

> + * maybe the v4l2 function should be public
> + */
> +static int vimc_cap_v4l2_subdev_link_validate_get_format(struct media_pad *pad,
> +						struct v4l2_subdev_format *fmt)
> +{
> +	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(pad->entity);
> +
> +	fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
> +	fmt->pad = pad->index;

A newline here would be nice.

> +	return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);
> +}
> +
> +static int vimc_cap_link_validate(struct media_link *link)
> +{
> +	struct v4l2_subdev_format source_fmt;
> +	struct v4l2_pix_format *sink_fmt;
> +	struct vimc_cap_device *vcap;
> +	const struct vimc_pix_map *vpix;
> +	int ret;
> +
> +	/* Retrieve the video capture device */
> +	vcap = container_of(link->sink->entity,
> +			    struct vimc_cap_device, vdev.entity);

You could assign in variable declaration.

> +
> +	/* If the connected node is not a subdevice type

Ditto.

> +	 * then it's a raw node from vimc-core, ignore the link for now

What's a raw node in this case?

> +	 * TODO: remove this when there are no more raw nodes in the
> +	 * core and return error instead
> +	 */
> +	if (!is_media_entity_v4l2_subdev(link->source->entity))
> +		return 0;
> +
> +	/* Get the the format of the video device */
> +	sink_fmt = &vcap->format;

Same for sink_fmt, you could assign it in variable declaration.

> +
> +	/* Get the the format of the subdev */
> +	ret = vimc_cap_v4l2_subdev_link_validate_get_format(link->source,
> +							    &source_fmt);
> +	if (ret)
> +		return ret;
> +
> +	dev_dbg(vcap->dev,
> +		"cap: %s: link validate formats src:%dx%d %d sink:%dx%d %d\n",
> +		vcap->vdev.name,
> +		source_fmt.format.width, source_fmt.format.height,
> +		source_fmt.format.code,
> +		sink_fmt->width, sink_fmt->height,
> +		sink_fmt->pixelformat);
> +
> +	/* Validate the format */
> +
> +	vpix = vimc_pix_map_by_pixelformat(sink_fmt->pixelformat);
> +	if (!vpix)
> +		return -EINVAL;
> +
> +	/* The width, height and code must match. */
> +	if (source_fmt.format.width != sink_fmt->width
> +	    || source_fmt.format.height != sink_fmt->height
> +	    || vpix->code != source_fmt.format.code)
> +		return -EINVAL;
> +
> +	/* The field order must match, or the sink field order must be NONE
> +	 * to support interlaced hardware connected to bridges that support
> +	 * progressive formats only.
> +	 */
> +	if (source_fmt.format.field != sink_fmt->field &&
> +	    sink_fmt->field != V4L2_FIELD_NONE)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static const struct media_entity_operations vimc_cap_mops = {
> +	.link_validate		= vimc_cap_link_validate,
> +};
> +
> +static void vimc_cap_destroy(struct vimc_ent_device *ved)
> +{
> +	struct vimc_cap_device *vcap = container_of(ved, struct vimc_cap_device,
> +						    ved);
> +
> +	vb2_queue_release(&vcap->queue);
> +	media_entity_cleanup(ved->ent);
> +	video_unregister_device(&vcap->vdev);
> +	vimc_pads_cleanup(vcap->ved.pads);
> +	kfree(vcap);
> +}
> +
> +static void vimc_cap_process_frame(struct vimc_ent_device *ved,
> +				   struct media_pad *sink, const void *frame)
> +{
> +	struct vimc_cap_device *vcap = container_of(ved, struct vimc_cap_device,
> +						    ved);
> +	struct vimc_cap_buffer *vimc_buf;
> +	void *vbuf;
> +
> +	/* If the stream in this node is not active, just return */
> +	mutex_lock(&vcap->lock);
> +	if (!vb2_is_busy(&vcap->queue)) {
> +		mutex_unlock(&vcap->lock);
> +		return;
> +	}
> +	mutex_unlock(&vcap->lock);
> +
> +	spin_lock(&vcap->qlock);
> +
> +	/* Get the first entry of the list */
> +	vimc_buf = list_first_entry_or_null(&vcap->buf_list,
> +					    typeof(*vimc_buf), list);
> +	if (!vimc_buf) {
> +		spin_unlock(&vcap->qlock);
> +		return;
> +	}
> +
> +	/* Remove this entry from the list */
> +	list_del(&vimc_buf->list);
> +
> +	spin_unlock(&vcap->qlock);
> +
> +	/* Fill the buffer */
> +	vimc_buf->vb2.vb2_buf.timestamp = ktime_get_ns();
> +	vimc_buf->vb2.sequence = vcap->sequence++;
> +	vimc_buf->vb2.field = vcap->format.field;
> +
> +	vbuf = vb2_plane_vaddr(&vimc_buf->vb2.vb2_buf, 0);
> +
> +	memcpy(vbuf, frame, vcap->format.sizeimage);
> +
> +	/* Set it as ready */
> +	vb2_set_plane_payload(&vimc_buf->vb2.vb2_buf, 0,
> +			      vcap->format.sizeimage);
> +	vb2_buffer_done(&vimc_buf->vb2.vb2_buf, VB2_BUF_STATE_DONE);
> +}
> +
> +struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
> +					const char *const name,
> +					u16 num_pads,
> +					const unsigned long *pads_flag)
> +{
> +	int ret;

It'd be nice to declare temporary variables, return values and such last.

> +	struct vb2_queue *q;
> +	struct video_device *vdev;
> +	struct vimc_cap_device *vcap;
> +	const struct vimc_pix_map *vpix;
> +
> +	/* Check entity configuration params

/*
 *

> +	 * NOTE: we only support a single sink pad
> +	 */
> +	if (!name || num_pads != 1 || !pads_flag ||
> +	    !(pads_flag[0] & MEDIA_PAD_FL_SINK))
> +		return ERR_PTR(-EINVAL);
> +
> +	/* Allocate the vimc_cap_device struct */
> +	vcap = kzalloc(sizeof(*vcap), GFP_KERNEL);
> +	if (!vcap)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Link the vimc_cap_device struct with v4l2 and dev parent */
> +	vcap->v4l2_dev = v4l2_dev;
> +	vcap->dev = v4l2_dev->dev;
> +
> +	/* Allocate the pads */
> +	vcap->ved.pads = vimc_pads_init(num_pads, pads_flag);
> +	if (IS_ERR(vcap->ved.pads)) {
> +		ret = PTR_ERR(vcap->ved.pads);
> +		goto err_free_vcap;
> +	}
> +
> +	/* Initialize the media entity */
> +	vcap->vdev.entity.name = name;
> +	vcap->vdev.entity.function = MEDIA_ENT_F_IO_V4L;
> +	ret = media_entity_pads_init(&vcap->vdev.entity,
> +				     num_pads, vcap->ved.pads);
> +	if (ret)
> +		goto err_clean_pads;
> +
> +	/* Initialize the lock */
> +	mutex_init(&vcap->lock);
> +
> +	/* Initialize the vb2 queue */
> +	q = &vcap->queue;
> +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	q->io_modes = VB2_MMAP | VB2_DMABUF;
> +	q->drv_priv = vcap;
> +	q->buf_struct_size = sizeof(struct vimc_cap_buffer);
> +	q->ops = &vimc_cap_qops;
> +	q->mem_ops = &vb2_vmalloc_memops;
> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	q->min_buffers_needed = 2;
> +	q->lock = &vcap->lock;
> +
> +	ret = vb2_queue_init(q);
> +	if (ret) {
> +		dev_err(vcap->dev,
> +			"vb2 queue init failed (err=%d)\n", ret);
> +		goto err_clean_m_ent;
> +	}
> +
> +	/* Initialize buffer list and its lock */
> +	INIT_LIST_HEAD(&vcap->buf_list);
> +	spin_lock_init(&vcap->qlock);
> +
> +	/* Set the frame format (this is hardcoded for now) */
> +	vcap->format.width = 640;
> +	vcap->format.height = 480;
> +	vcap->format.pixelformat = V4L2_PIX_FMT_RGB24;
> +	vcap->format.field = V4L2_FIELD_NONE;
> +	vcap->format.colorspace = V4L2_COLORSPACE_SRGB;
> +
> +	vpix = vimc_pix_map_by_pixelformat(vcap->format.pixelformat);
> +
> +	vcap->format.bytesperline = vcap->format.width * vpix->bpp;
> +	vcap->format.sizeimage = vcap->format.bytesperline *
> +				 vcap->format.height;
> +
> +	/* Fill the vimc_ent_device struct */
> +	vcap->ved.destroy = vimc_cap_destroy;
> +	vcap->ved.ent = &vcap->vdev.entity;
> +	vcap->ved.process_frame = vimc_cap_process_frame;
> +
> +	/* Initialize the video_device struct */
> +	vdev = &vcap->vdev;
> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
> +	vdev->entity.ops = &vimc_cap_mops;
> +	vdev->release = video_device_release_empty;
> +	vdev->fops = &vimc_cap_fops;
> +	vdev->ioctl_ops = &vimc_cap_ioctl_ops;
> +	vdev->lock = &vcap->lock;
> +	vdev->queue = q;
> +	vdev->v4l2_dev = vcap->v4l2_dev;
> +	vdev->vfl_dir = VFL_DIR_RX;
> +	strlcpy(vdev->name, name, sizeof(vdev->name));
> +	video_set_drvdata(vdev, vcap);
> +
> +	/* Register the video_device with the v4l2 and the media framework */
> +	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
> +	if (ret) {
> +		dev_err(vcap->dev,
> +			"video register failed (err=%d)\n", ret);
> +		goto err_release_queue;
> +	}
> +
> +	return &vcap->ved;
> +
> +err_release_queue:
> +	vb2_queue_release(q);
> +err_clean_m_ent:
> +	media_entity_cleanup(&vcap->vdev.entity);
> +err_clean_pads:
> +	vimc_pads_cleanup(vcap->ved.pads);
> +err_free_vcap:
> +	kfree(vcap);
> +
> +	return ERR_PTR(ret);
> +}
> diff --git a/drivers/media/platform/vimc/vimc-capture.h b/drivers/media/platform/vimc/vimc-capture.h
> new file mode 100644
> index 0000000..bcf9fc37
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-capture.h
> @@ -0,0 +1,28 @@
> +/*
> + * vimc-capture.h Virtual Media Controller Driver
> + *
> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#ifndef _VIMC_CAPTURE_H_
> +#define _VIMC_CAPTURE_H_
> +
> +#include "vimc-core.h"
> +
> +struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
> +					const char *const name,
> +					u16 num_pads,
> +					const unsigned long *pads_flag);
> +
> +#endif
> diff --git a/drivers/media/platform/vimc/vimc-core.c b/drivers/media/platform/vimc/vimc-core.c
> new file mode 100644
> index 0000000..0a2b91b
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-core.c
> @@ -0,0 +1,600 @@
> +/*
> + * vimc-core.c Virtual Media Controller Driver
> + *
> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <media/media-device.h>
> +#include <media/v4l2-device.h>
> +
> +#include "vimc-capture.h"
> +#include "vimc-core.h"
> +#include "vimc-sensor.h"
> +
> +#define VIMC_PDEV_NAME "vimc"
> +#define VIMC_MDEV_MODEL_NAME "VIMC MDEV"
> +
> +#define VIMC_ENT_LINK(src, srcpad, sink, sinkpad, link_flags) {	\
> +	.src_ent = src,						\
> +	.src_pad = srcpad,					\
> +	.sink_ent = sink,					\
> +	.sink_pad = sinkpad,					\
> +	.flags = link_flags,					\
> +}
> +
> +#define VIMC_PIX_MAP(_code, _bpp, _pixelformat) {	\
> +	.code = _code,					\
> +	.pixelformat = _pixelformat,			\
> +	.bpp = _bpp,					\
> +}
> +
> +struct vimc_device {
> +	/* The pipeline configuration

/*
 *

> +	 * (filled before calling vimc_device_register)
> +	 */
> +	const struct vimc_pipeline_config *pipe_cfg;
> +
> +	/* The Associated media_device parent */
> +	struct media_device mdev;
> +
> +	/* Internal v4l2 parent device*/
> +	struct v4l2_device v4l2_dev;
> +
> +	/* Internal topology */
> +	struct vimc_ent_device **ved;
> +};
> +
> +/**
> + * enum vimc_ent_node - Select the functionality of a node in the topology
> + * @VIMC_ENT_NODE_SENSOR:	A node of type SENSOR simulates a camera sensor
> + *				generating internal images in bayer format and
> + *				propagating those images through the pipeline
> + * @VIMC_ENT_NODE_CAPTURE:	A node of type CAPTURE is a v4l2 video_device
> + *				that exposes the received image from the
> + *				pipeline to the user space
> + * @VIMC_ENT_NODE_INPUT:	A node of type INPUT is a v4l2 video_device that
> + *				receives images from the user space and
> + *				propagates them through the pipeline
> + * @VIMC_ENT_NODE_DEBAYER:	A node type DEBAYER expects to receive a frame
> + *				in bayer format converts it to RGB
> + * @VIMC_ENT_NODE_SCALER:	A node of type SCALER scales the received image
> + *				by a given multiplier
> + *
> + * This enum is used in the entity configuration struct to allow the definition
> + * of a custom topology specifying the role of each node on it.
> + */
> +enum vimc_ent_node {
> +	VIMC_ENT_NODE_SENSOR,
> +	VIMC_ENT_NODE_CAPTURE,
> +	VIMC_ENT_NODE_INPUT,
> +	VIMC_ENT_NODE_DEBAYER,
> +	VIMC_ENT_NODE_SCALER,
> +};
> +
> +/* Structure which describes individual configuration for each entity */
> +struct vimc_ent_config {
> +	const char *name;
> +	size_t pads_qty;
> +	const unsigned long *pads_flag;
> +	enum vimc_ent_node node;
> +};
> +
> +/* Structure which describes links between entities */
> +struct vimc_ent_link {
> +	unsigned int src_ent;
> +	u16 src_pad;
> +	unsigned int sink_ent;
> +	u16 sink_pad;
> +	u32 flags;
> +};
> +
> +/* Structure which describes the whole topology */
> +struct vimc_pipeline_config {
> +	const struct vimc_ent_config *ents;
> +	size_t num_ents;
> +	const struct vimc_ent_link *links;
> +	size_t num_links;
> +};
> +
> +/* --------------------------------------------------------------------------
> + * Topology Configuration
> + */
> +
> +static const struct vimc_ent_config ent_config[] = {
> +	{
> +		.name = "Sensor A",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_SENSOR,
> +	},
> +	{
> +		.name = "Sensor B",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_SENSOR,
> +	},
> +	{
> +		.name = "Debayer A",
> +		.pads_qty = 2,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
> +						     MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_DEBAYER,
> +	},
> +	{
> +		.name = "Debayer B",
> +		.pads_qty = 2,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
> +						     MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_DEBAYER,
> +	},
> +	{
> +		.name = "Raw Capture 0",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
> +		.node = VIMC_ENT_NODE_CAPTURE,
> +	},
> +	{
> +		.name = "Raw Capture 1",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
> +		.node = VIMC_ENT_NODE_CAPTURE,
> +	},
> +	{
> +		.name = "RGB/YUV Input",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_INPUT,
> +	},
> +	{
> +		.name = "Scaler",
> +		.pads_qty = 2,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
> +						     MEDIA_PAD_FL_SOURCE},
> +		.node = VIMC_ENT_NODE_SCALER,
> +	},
> +	{
> +		.name = "RGB/YUV Capture",
> +		.pads_qty = 1,
> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
> +		.node = VIMC_ENT_NODE_CAPTURE,
> +	},
> +};
> +
> +static const struct vimc_ent_link ent_links[] = {
> +	/* Link: Sensor A (Pad 0)->(Pad 0) Debayer A */
> +	VIMC_ENT_LINK(0, 0, 2, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Sensor A (Pad 0)->(Pad 0) Raw Capture 0 */
> +	VIMC_ENT_LINK(0, 0, 4, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Sensor B (Pad 0)->(Pad 0) Debayer B */
> +	VIMC_ENT_LINK(1, 0, 3, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Sensor B (Pad 0)->(Pad 0) Raw Capture 1 */
> +	VIMC_ENT_LINK(1, 0, 5, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
> +	/* Link: Debayer A (Pad 1)->(Pad 0) Scaler */
> +	VIMC_ENT_LINK(2, 1, 7, 0, MEDIA_LNK_FL_ENABLED),
> +	/* Link: Debayer B (Pad 1)->(Pad 0) Scaler */
> +	VIMC_ENT_LINK(3, 1, 7, 0, 0),
> +	/* Link: RGB/YUV Input (Pad 0)->(Pad 0) Scaler */
> +	VIMC_ENT_LINK(6, 0, 7, 0, 0),
> +	/* Link: Scaler (Pad 1)->(Pad 0) RGB/YUV Capture */
> +	VIMC_ENT_LINK(7, 1, 8, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
> +};
> +
> +static const struct vimc_pipeline_config pipe_cfg = {
> +	.ents		= ent_config,
> +	.num_ents	= ARRAY_SIZE(ent_config),
> +	.links		= ent_links,
> +	.num_links	= ARRAY_SIZE(ent_links)
> +};
> +
> +/* -------------------------------------------------------------------------- */
> +
> +static void vimc_dev_release(struct device *dev)
> +{}
> +
> +static struct platform_device vimc_pdev = {
> +	.name		= VIMC_PDEV_NAME,
> +	.dev.release	= vimc_dev_release,
> +};
> +
> +const struct vimc_pix_map vimc_pix_map_list[] = {
> +	/* TODO: add all missing formats */
> +
> +	/* RGB formats */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_BGR888_1X24, 3, V4L2_PIX_FMT_BGR24),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_RGB888_1X24, 3, V4L2_PIX_FMT_RGB24),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_ARGB8888_1X32, 4, V4L2_PIX_FMT_ARGB32),
> +
> +	/* Bayer formats */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR8_1X8, 1, V4L2_PIX_FMT_SBGGR8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG8_1X8, 1, V4L2_PIX_FMT_SGBRG8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG8_1X8, 1, V4L2_PIX_FMT_SGRBG8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB8_1X8, 1, V4L2_PIX_FMT_SRGGB8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_1X10, 2, V4L2_PIX_FMT_SBGGR10),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_1X10, 2, V4L2_PIX_FMT_SGBRG10),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_1X10, 2, V4L2_PIX_FMT_SGRBG10),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_1X10, 2, V4L2_PIX_FMT_SRGGB10),
> +	/* 10bit raw bayer a-law compressed to 8 bits */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_ALAW8_1X8, 1, V4L2_PIX_FMT_SBGGR10ALAW8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGBRG10ALAW8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGRBG10ALAW8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_ALAW8_1X8, 1, V4L2_PIX_FMT_SRGGB10ALAW8),
> +	/* 10bit raw bayer DPCM compressed to 8 bits */
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_DPCM8_1X8, 1, V4L2_PIX_FMT_SBGGR10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGBRG10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGRBG10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_DPCM8_1X8, 1, V4L2_PIX_FMT_SRGGB10DPCM8),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR12_1X12, 2, V4L2_PIX_FMT_SBGGR12),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG12_1X12, 2, V4L2_PIX_FMT_SGBRG12),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG12_1X12, 2, V4L2_PIX_FMT_SGRBG12),
> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB12_1X12, 2, V4L2_PIX_FMT_SRGGB12),
> +
> +	/* End */
> +	{0, 0, 0}
> +};
> +
> +const struct vimc_pix_map *vimc_pix_map_by_code(u32 code)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
> +		if (vimc_pix_map_list[i].code == code)
> +			return &vimc_pix_map_list[i];
> +	}
> +	return NULL;
> +}
> +
> +const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
> +		if (vimc_pix_map_list[i].pixelformat == pixelformat)
> +			return &vimc_pix_map_list[i];
> +	}
> +	return NULL;
> +}
> +
> +int vimc_propagate_frame(struct device *dev,
> +			 struct media_pad *src, const void *frame)
> +{
> +	struct media_link *link;
> +	struct vimc_device *vimc = dev_get_drvdata(dev);
> +
> +	if (!(src->flags & MEDIA_PAD_FL_SOURCE))
> +		return -EINVAL;
> +
> +	/* Send this frame to all sink pads that are direct linked */
> +	list_for_each_entry(link, &src->entity->links, list) {
> +		if (link->source == src &&
> +		    (link->flags & MEDIA_LNK_FL_ENABLED)) {
> +			struct vimc_ent_device *ved;
> +
> +			ved = vimc->ved[link->sink->entity->use_count];
> +			if (ved && ved->process_frame)
> +				ved->process_frame(ved, link->sink, frame);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static void vimc_device_unregister(struct vimc_device *vimc)
> +{
> +	unsigned int i;
> +
> +	/* Cleanup (only initialized) entities */
> +	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
> +		if (vimc->ved[i] && vimc->ved[i]->destroy)
> +			vimc->ved[i]->destroy(vimc->ved[i]);
> +
> +		vimc->ved[i] = NULL;
> +	}
> +	v4l2_device_unregister(&vimc->v4l2_dev);
> +
> +	media_device_unregister(&vimc->mdev);
> +	media_device_cleanup(&vimc->mdev);
> +}
> +
> +/* Helper function to allocate and initialize pads */
> +struct media_pad *vimc_pads_init(u16 num_pads, const unsigned long *pads_flag)
> +{
> +	unsigned int i;
> +	struct media_pad *pads;
> +
> +	/* Allocate memory for the pads */
> +	pads = kcalloc(num_pads, sizeof(*pads), GFP_KERNEL);
> +	if (!pads)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Initialize the pads */
> +	for (i = 0; i < num_pads; i++) {
> +		pads[i].index = i;
> +		pads[i].flags = pads_flag[i];
> +	}
> +
> +	return pads;
> +}
> +
> +/* TODO: remove this function when all the
> + * entities specific code are implemented
> + */
> +static void vimc_raw_destroy(struct vimc_ent_device *ved)
> +{
> +	media_device_unregister_entity(ved->ent);
> +
> +	media_entity_cleanup(ved->ent);
> +
> +	vimc_pads_cleanup(ved->pads);
> +
> +	kfree(ved->ent);
> +
> +	kfree(ved);
> +}
> +
> +/* TODO: remove this function when all the
> + * entities specific code are implemented
> + */
> +static struct vimc_ent_device *vimc_raw_create(struct v4l2_device *v4l2_dev,
> +					       const char *const name,
> +					       u16 num_pads,
> +					       const unsigned long *pads_flag)
> +{
> +	int ret;
> +	struct vimc_ent_device *ved;
> +
> +	/* Allocate the main ved struct */
> +	ved = kzalloc(sizeof(*ved), GFP_KERNEL);
> +	if (!ved)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Allocate the media entity */
> +	ved->ent = kzalloc(sizeof(*ved->ent), GFP_KERNEL);
> +	if (!ved->ent) {
> +		ret = -ENOMEM;
> +		goto err_free_ved;
> +	}
> +
> +	/* Allocate the pads */
> +	ved->pads = vimc_pads_init(num_pads, pads_flag);
> +	if (IS_ERR(ved->pads)) {
> +		ret = PTR_ERR(ved->pads);
> +		goto err_free_ent;
> +	}
> +
> +	/* Initialize the media entity */
> +	ved->ent->name = name;
> +	ved->ent->function = MEDIA_ENT_F_IO_V4L;
> +	ret = media_entity_pads_init(ved->ent, num_pads, ved->pads);
> +	if (ret)
> +		goto err_cleanup_pads;
> +
> +	/* Register the media entity */
> +	ret = media_device_register_entity(v4l2_dev->mdev, ved->ent);
> +	if (ret)
> +		goto err_cleanup_entity;
> +
> +	/* Fill out the destroy function and return */
> +	ved->destroy = vimc_raw_destroy;
> +	return ved;
> +
> +err_cleanup_entity:
> +	media_entity_cleanup(ved->ent);
> +err_cleanup_pads:
> +	vimc_pads_cleanup(ved->pads);
> +err_free_ent:
> +	kfree(ved->ent);
> +err_free_ved:
> +	kfree(ved);
> +
> +	return ERR_PTR(ret);
> +}
> +
> +static int vimc_device_register(struct vimc_device *vimc)
> +{
> +	unsigned int i;
> +	int ret = 0;
> +
> +	/* Allocate memory for the vimc_ent_devices pointers */
> +	vimc->ved = devm_kcalloc(vimc->mdev.dev, vimc->pipe_cfg->num_ents,
> +				 sizeof(*vimc->ved), GFP_KERNEL);
> +	if (!vimc->ved)
> +		return -ENOMEM;
> +
> +	/* Register the media device */
> +	ret = media_device_register(&vimc->mdev);
> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"media device register failed (err=%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Link the media device within the v4l2_device */
> +	vimc->v4l2_dev.mdev = &vimc->mdev;
> +
> +	/* Register the v4l2 struct */
> +	ret = v4l2_device_register(vimc->mdev.dev, &vimc->v4l2_dev);
> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"v4l2 device register failed (err=%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Initialize entities */
> +	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
> +		struct vimc_ent_device *(*create_func)(struct v4l2_device *,
> +						       const char *const,
> +						       u16,
> +						       const unsigned long *);
> +
> +		/* Register the specific node */
> +		switch (vimc->pipe_cfg->ents[i].node) {
> +		case VIMC_ENT_NODE_SENSOR:
> +			create_func = vimc_sen_create;
> +			break;
> +
> +		case VIMC_ENT_NODE_CAPTURE:
> +			create_func = vimc_cap_create;
> +			break;
> +
> +		/* TODO: Instantiate the specific topology node */
> +		case VIMC_ENT_NODE_INPUT:
> +		case VIMC_ENT_NODE_DEBAYER:
> +		case VIMC_ENT_NODE_SCALER:
> +		default:
> +			/* TODO: remove this when all the entities specific
> +			 * code are implemented
> +			 */
> +			create_func = vimc_raw_create;
> +			break;
> +		}
> +
> +		vimc->ved[i] = create_func(&vimc->v4l2_dev,
> +					   vimc->pipe_cfg->ents[i].name,
> +					   vimc->pipe_cfg->ents[i].pads_qty,
> +					   vimc->pipe_cfg->ents[i].pads_flag);
> +		if (IS_ERR(vimc->ved[i])) {
> +			ret = PTR_ERR(vimc->ved[i]);
> +			vimc->ved[i] = NULL;
> +			goto err;
> +		}
> +
> +		/* Set use_count to keep track of the ved structure */
> +		vimc->ved[i]->ent->use_count = i;
> +	}
> +
> +	/* Initialize the links between entities */
> +	for (i = 0; i < vimc->pipe_cfg->num_links; i++) {
> +		const struct vimc_ent_link *link = &vimc->pipe_cfg->links[i];
> +
> +		ret = media_create_pad_link(vimc->ved[link->src_ent]->ent,
> +					    link->src_pad,
> +					    vimc->ved[link->sink_ent]->ent,
> +					    link->sink_pad,
> +					    link->flags);
> +		if (ret)
> +			goto err;
> +	}
> +
> +	/* Expose all subdev's nodes*/
> +	ret = v4l2_device_register_subdev_nodes(&vimc->v4l2_dev);
> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"vimc subdev nodes registration failed (err=%d)\n",
> +			ret);
> +		goto err;
> +	}
> +
> +	return 0;
> +
> +err:
> +	/* Destroy the so far created topology */
> +	vimc_device_unregister(vimc);
> +
> +	return ret;
> +}
> +
> +static int vimc_probe(struct platform_device *pdev)
> +{
> +	struct vimc_device *vimc;
> +	int ret;
> +
> +	/* Prepare the vimc topology structure */
> +
> +	/* Allocate memory for the vimc structure */
> +	vimc = devm_kzalloc(&pdev->dev, sizeof(*vimc), GFP_KERNEL);
> +	if (!vimc)
> +		return -ENOMEM;
> +
> +	/* Set the pipeline configuration struct */
> +	vimc->pipe_cfg = &pipe_cfg;
> +
> +	/* Initialize media device */
> +	strlcpy(vimc->mdev.model, VIMC_MDEV_MODEL_NAME,
> +		sizeof(vimc->mdev.model));
> +	vimc->mdev.dev = &pdev->dev;
> +	media_device_init(&vimc->mdev);
> +
> +	/* Create vimc topology */
> +	ret = vimc_device_register(vimc);
> +	if (ret) {
> +		dev_err(vimc->mdev.dev,
> +			"vimc device registration failed (err=%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Link the topology object with the platform device object */
> +	platform_set_drvdata(pdev, vimc);
> +
> +	return 0;
> +}
> +
> +static int vimc_remove(struct platform_device *pdev)
> +{
> +	struct vimc_device *vimc;
> +
> +	/* Get the topology object linked with the platform device object */
> +	vimc = platform_get_drvdata(pdev);

You should assign in variable declaration.

> +
> +	/* Destroy all the topology */
> +	vimc_device_unregister(vimc);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver vimc_pdrv = {
> +	.probe		= vimc_probe,
> +	.remove		= vimc_remove,
> +	.driver		= {
> +		.name	= VIMC_PDEV_NAME,
> +	},
> +};
> +
> +static int __init vimc_init(void)
> +{
> +	int ret;
> +
> +	ret = platform_device_register(&vimc_pdev);

You could declare vimc_pdev closer to this.

> +	if (ret) {
> +		dev_err(&vimc_pdev.dev,
> +			"platform device registration failed (err=%d)\n", ret);
> +		return ret;
> +	}
> +
> +	ret = platform_driver_register(&vimc_pdrv);
> +	if (ret) {
> +		dev_err(&vimc_pdev.dev,
> +			"platform driver registration failed (err=%d)\n", ret);
> +
> +		platform_device_unregister(&vimc_pdev);
> +	}
> +
> +	return ret;
> +}
> +
> +static void __exit vimc_exit(void)
> +{
> +	platform_driver_unregister(&vimc_pdrv);
> +
> +	platform_device_unregister(&vimc_pdev);
> +}
> +
> +module_init(vimc_init);
> +module_exit(vimc_exit);
> +
> +MODULE_DESCRIPTION("Virtual Media Controller Driver (VIMC)");
> +MODULE_AUTHOR("Helen Fornazier <helen.fornazier@gmail.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/media/platform/vimc/vimc-core.h b/drivers/media/platform/vimc/vimc-core.h
> new file mode 100644
> index 0000000..bd7abff
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-core.h
> @@ -0,0 +1,57 @@
> +/*
> + * vimc-core.h Virtual Media Controller Driver
> + *
> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#ifndef _VIMC_CORE_H_
> +#define _VIMC_CORE_H_
> +
> +#include <linux/slab.h>
> +#include <media/v4l2-device.h>
> +
> +/* Struct which matches the MEDIA_BUS_FMT_ codes with the corresponding

/*

> + * V4L2_PIX_FMT_ fourcc pixelformat and its bytes per pixel (bpp)
> + */
> +struct vimc_pix_map {
> +	unsigned int code;
> +	unsigned int bpp;
> +	u32 pixelformat;
> +};
> +extern const struct vimc_pix_map vimc_pix_map_list[];
> +
> +struct vimc_ent_device {
> +	struct media_entity *ent;
> +	struct media_pad *pads;
> +	void (*destroy)(struct vimc_ent_device *);
> +	void (*process_frame)(struct vimc_ent_device *ved,
> +			      struct media_pad *sink, const void *frame);
> +};
> +
> +int vimc_propagate_frame(struct device *dev,
> +			 struct media_pad *src, const void *frame);
> +
> +/* Helper functions to allocate/initialize pads and free them */
> +struct media_pad *vimc_pads_init(u16 num_pads,
> +				 const unsigned long *pads_flag);
> +static inline void vimc_pads_cleanup(struct media_pad *pads)
> +{
> +	kfree(pads);
> +}
> +
> +const struct vimc_pix_map *vimc_pix_map_by_code(u32 code);
> +
> +const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat);
> +
> +#endif
> diff --git a/drivers/media/platform/vimc/vimc-sensor.c b/drivers/media/platform/vimc/vimc-sensor.c
> new file mode 100644
> index 0000000..174e5dc
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-sensor.c
> @@ -0,0 +1,279 @@
> +/*
> + * vimc-sensor.c Virtual Media Controller Driver
> + *
> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/freezer.h>
> +#include <linux/kthread.h>
> +#include <linux/vmalloc.h>
> +#include <linux/v4l2-mediabus.h>
> +#include <media/v4l2-subdev.h>

Alphabetic order, please.

> +
> +#include "vimc-sensor.h"
> +
> +struct vimc_sen_device {
> +	struct vimc_ent_device ved;
> +	struct v4l2_subdev sd;
> +	struct v4l2_device *v4l2_dev;
> +	struct device *dev;
> +	struct task_struct *kthread_sen;
> +	u8 *frame;
> +	/* The active format */
> +	struct v4l2_mbus_framefmt mbus_format;
> +	int frame_size;
> +};
> +
> +static int vimc_sen_enum_mbus_code(struct v4l2_subdev *sd,
> +				   struct v4l2_subdev_pad_config *cfg,
> +				   struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
> +
> +	/* Check if it is a valid pad */
> +	if (code->pad >= vsen->sd.entity.num_pads)
> +		return -EINVAL;

The check is already performed in v4l2-subdev.c.

> +
> +	code->code = vsen->mbus_format.code;
> +
> +	return 0;
> +}
> +
> +static int vimc_sen_enum_frame_size(struct v4l2_subdev *sd,
> +				    struct v4l2_subdev_pad_config *cfg,
> +				    struct v4l2_subdev_frame_size_enum *fse)
> +{
> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
> +
> +	/* Check if it is a valid pad */
> +	if (fse->pad >= vsen->sd.entity.num_pads)
> +		return -EINVAL;

Same here.

> +
> +	/* TODO: Add support to other formats */
> +	if (fse->index)
> +		return -EINVAL;
> +
> +	/* TODO: Add support for other codes */
> +	if (fse->code != vsen->mbus_format.code)
> +		return -EINVAL;
> +
> +	fse->min_width = vsen->mbus_format.width;
> +	fse->max_width = vsen->mbus_format.width;
> +	fse->min_height = vsen->mbus_format.height;
> +	fse->max_height = vsen->mbus_format.height;
> +
> +	return 0;
> +}
> +
> +static int vimc_sen_get_fmt(struct v4l2_subdev *sd,
> +			    struct v4l2_subdev_pad_config *cfg,
> +			    struct v4l2_subdev_format *format)
> +{
> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
> +
> +	format->format = vsen->mbus_format;
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_pad_ops vimc_sen_pad_ops = {
> +	.enum_mbus_code		= vimc_sen_enum_mbus_code,
> +	.enum_frame_size	= vimc_sen_enum_frame_size,
> +	.get_fmt		= vimc_sen_get_fmt,
> +	/* TODO: Add support to other formats */
> +	.set_fmt		= vimc_sen_get_fmt,
> +};
> +
> +/* media operations */
> +static const struct media_entity_operations vimc_sen_mops = {
> +	.link_validate = v4l2_subdev_link_validate,
> +};
> +
> +static int vimc_thread_sen(void *data)
> +{
> +	unsigned int i;
> +	struct vimc_sen_device *vsen = data;
> +
> +	set_freezable();
> +
> +	for (;;) {
> +		try_to_freeze();
> +		if (kthread_should_stop())
> +			break;
> +
> +		memset(vsen->frame, 100, vsen->frame_size);
> +
> +		/* Send the frame to all source pads */
> +		for (i = 0; i < vsen->sd.entity.num_pads; i++)
> +			vimc_propagate_frame(vsen->dev,
> +					     &vsen->sd.entity.pads[i],
> +					     vsen->frame);
> +
> +		/* 60 frames per second */
> +		schedule_timeout_interruptible(HZ/60);
> +	}
> +
> +	return 0;
> +}
> +
> +static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
> +{
> +	int ret;
> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
> +
> +	if (enable) {
> +		const struct vimc_pix_map *vpix;
> +
> +		if (vsen->kthread_sen)
> +			return -EINVAL;
> +
> +		/* Calculate the frame size */
> +		vpix = vimc_pix_map_by_code(vsen->mbus_format.code);
> +		vsen->frame_size = vsen->mbus_format.width * vpix->bpp *
> +				   vsen->mbus_format.height;
> +
> +		/* Allocate the frame buffer. Use vmalloc to be able to

/*
 *

> +		 * allocate a large amount of memory
> +		 */
> +		vsen->frame = vmalloc(vsen->frame_size);
> +		if (!vsen->frame)
> +			return -ENOMEM;
> +
> +		/* Initialize the image generator thread */
> +		vsen->kthread_sen = kthread_run(vimc_thread_sen, vsen,
> +						"%s-sen", vsen->v4l2_dev->name);

We have no other kthreads, just the video device name should be enough.

> +		if (IS_ERR(vsen->kthread_sen)) {
> +			v4l2_err(vsen->v4l2_dev, "kernel_thread() failed\n");

How about dev_err() instead? You use dev_*() macros elsewhere for printing.

> +			vfree(vsen->frame);
> +			vsen->frame = NULL;
> +			return PTR_ERR(vsen->kthread_sen);
> +		}
> +	} else {
> +		if (!vsen->kthread_sen)
> +			return -EINVAL;
> +
> +		/* Stop image generator */
> +		ret = kthread_stop(vsen->kthread_sen);
> +		vsen->kthread_sen = NULL;
> +
> +		vfree(vsen->frame);
> +		vsen->frame = NULL;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +struct v4l2_subdev_video_ops vimc_sen_video_ops = {
> +	.s_stream = vimc_sen_s_stream,
> +};
> +
> +static const struct v4l2_subdev_ops vimc_sen_ops = {
> +	.pad = &vimc_sen_pad_ops,
> +	.video = &vimc_sen_video_ops,
> +};
> +
> +static void vimc_sen_destroy(struct vimc_ent_device *ved)
> +{
> +	struct vimc_sen_device *vsen = container_of(ved,
> +						struct vimc_sen_device, ved);
> +
> +	media_entity_cleanup(ved->ent);
> +	v4l2_device_unregister_subdev(&vsen->sd);

I'd say media_entity_cleanup() would belong here but it's an empty function
nowadays...

> +	kfree(vsen);
> +}
> +
> +struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
> +					const char *const name,
> +					u16 num_pads,
> +					const unsigned long *pads_flag)
> +{
> +	int ret;
> +	unsigned int i;
> +	struct vimc_sen_device *vsen;

vsen first?

> +
> +	if (!name || (num_pads && !pads_flag))
> +		return ERR_PTR(-EINVAL);
> +	/* check if all pads are sources */
> +	for (i = 0; i < num_pads; i++)
> +		if (!(pads_flag[i] & MEDIA_PAD_FL_SOURCE))
> +			return ERR_PTR(-EINVAL);
> +
> +	/* Allocate the vsen struct */
> +	vsen = kzalloc(sizeof(*vsen), GFP_KERNEL);
> +	if (!vsen)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* Link the vimc_sen_device struct with the v4l2 parent */
> +	vsen->v4l2_dev = v4l2_dev;
> +	/* Link the vimc_sen_device struct with the dev parent */
> +	vsen->dev = v4l2_dev->dev;
> +
> +	/* Allocate the pads */
> +	vsen->ved.pads = vimc_pads_init(num_pads, pads_flag);
> +	if (IS_ERR(vsen->ved.pads)) {
> +		ret = PTR_ERR(vsen->ved.pads);
> +		goto err_free_vsen;
> +	}
> +
> +	/* Initialize the media entity */
> +	vsen->sd.entity.name = name;
> +	ret = media_entity_pads_init(&vsen->sd.entity,
> +				     num_pads, vsen->ved.pads);
> +	if (ret)
> +		goto err_clean_pads;
> +
> +	/* Set the active frame format (this is hardcoded for now) */
> +	vsen->mbus_format.width = 640;
> +	vsen->mbus_format.height = 480;
> +	vsen->mbus_format.code = MEDIA_BUS_FMT_RGB888_1X24;
> +	vsen->mbus_format.field = V4L2_FIELD_NONE;
> +	vsen->mbus_format.colorspace = V4L2_COLORSPACE_SRGB;
> +	vsen->mbus_format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
> +	vsen->mbus_format.xfer_func = V4L2_XFER_FUNC_SRGB;
> +
> +	/* Fill the vimc_ent_device struct */
> +	vsen->ved.destroy = vimc_sen_destroy;
> +	vsen->ved.ent = &vsen->sd.entity;
> +
> +	/* Initialize the subdev */
> +	v4l2_subdev_init(&vsen->sd, &vimc_sen_ops);
> +	vsen->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
> +	vsen->sd.entity.ops = &vimc_sen_mops;
> +	vsen->sd.owner = THIS_MODULE;
> +	strlcpy(vsen->sd.name, name, sizeof(vsen->sd.name));
> +	v4l2_set_subdevdata(&vsen->sd, vsen);
> +
> +	/* Expose this subdev to user space */
> +	vsen->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
> +
> +	/* Register the subdev with the v4l2 and the media framework */
> +	ret = v4l2_device_register_subdev(vsen->v4l2_dev, &vsen->sd);
> +	if (ret) {
> +		dev_err(vsen->dev,
> +			"subdev register failed (err=%d)\n", ret);
> +		goto err_clean_m_ent;
> +	}
> +
> +	return &vsen->ved;
> +
> +err_clean_m_ent:
> +	media_entity_cleanup(&vsen->sd.entity);
> +err_clean_pads:
> +	vimc_pads_cleanup(vsen->ved.pads);
> +err_free_vsen:
> +	kfree(vsen);
> +
> +	return ERR_PTR(ret);
> +}
> diff --git a/drivers/media/platform/vimc/vimc-sensor.h b/drivers/media/platform/vimc/vimc-sensor.h
> new file mode 100644
> index 0000000..ffeaf6c
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-sensor.h
> @@ -0,0 +1,28 @@
> +/*
> + * vimc-sensor.h Virtual Media Controller Driver
> + *
> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#ifndef _VIMC_SENSOR_H_
> +#define _VIMC_SENSOR_H_
> +
> +#include "vimc-core.h"
> +
> +struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
> +					const char *const name,
> +					u16 num_pads,
> +					const unsigned long *pads_flag);
> +
> +#endif

Looks very nice in general! I'll try this out soon.
Mauro Carvalho Chehab Jan. 25, 2017, 3:31 p.m. UTC | #5
I won't be doing a review on it yet... I'll try to do it on the next
version. Just a quick notice:

Em Wed, 25 Jan 2017 15:03:46 +0200
Sakari Ailus <sakari.ailus@iki.fi> escreveu:

> > + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>  
> 
> 2017 might be used now.

Please keep 2016 as the year you did the initial development. It
makes sense to change it to:
	2016-2017

In order to reflect that you're also doing some work on it this year,
but preserving the initial date is important, IMHO.
Hans Verkuil March 10, 2017, 1:08 p.m. UTC | #6
Hi Helen,

On 11/01/17 02:30, Helen Koike wrote:
> 
> Thank you for the review, I'll update the patch accordingly and re-submit it.
> 
> Helen

Do you know when you have a v7 ready?

We really need a vimc driver so people without hardware can actually fiddle around
with the MC.

See also my rant here (not directed at you!):

https://www.spinics.net/lists/kernel/msg2462009.html

Regards,

	Hans
Helen Koike March 10, 2017, 1:42 p.m. UTC | #7
Hi Hans,

On 2017-03-10 10:08 AM, Hans Verkuil wrote:
> Hi Helen,
>
> On 11/01/17 02:30, Helen Koike wrote:
> >
> > Thank you for the review, I'll update the patch accordingly and re-submit it.
> >
> > Helen
>
> Do you know when you have a v7 ready?

Thanks for your interest. I don't have the next version entirely ready yet but I'll work on it to send this next version asap and the other patches I have on top of it as well.

>
> We really need a vimc driver so people without hardware can actually fiddle around
> with the MC.
>
> See also my rant here (not directed at you!):
>
> https://www.spinics.net/lists/kernel/msg2462009.html
>
> Regards,
>
>     Hans
>
Helen
Helen Koike March 24, 2017, 10:11 p.m. UTC | #8
Hi Sakari,

Thanks for your review, I have some questions below:

On 2017-01-25 11:03 AM, Sakari Ailus wrote:
> Hi Helen,
>
> My apologies for the long review time!
>
> Please see my comments below.
>
> On Sun, Sep 04, 2016 at 05:02:18PM -0300, Helen Koike wrote:
>> From: Helen Fornazier <helen.fornazier@gmail.com>
>>
>> First version of the Virtual Media Controller.
>> Add a simple version of the core of the driver, the capture and
>> sensor nodes in the topology, generating a grey image in a hardcoded
>> format.
>>
>> Signed-off-by: Helen Koike <helen.koike@collabora.com>
>>
>> ---
>>
>> Patch based in media/master tree, and available here:
>> https://github.com/helen-fornazier/opw-staging/tree/vimc/devel/vpu
>>
>> Changes since v5:
>> - Fix message "Entity type for entity Sensor A was not initialized!"
>>   by initializing the sensor entity.function after the calling
>>   v4l2_subded_init
>> - populate device_caps in vimc_cap_create instead of in
>>   vimc_cap_querycap
>> - Fix typo in vimc-core.c s/de/the
>>
>> Changes since v4:
>> - coding style fixes
>> - remove BUG_ON
>> - change copyright to 2016
>> - depens on VIDEO_V4L2_SUBDEV_API instead of select
>> - remove assignement of V4L2_CAP_DEVICE_CAPS
>> - s/vimc_cap_g_fmt_vid_cap/vimc_cap_fmt_vid_cap
>> - fix vimc_cap_queue_setup declaration type
>> - remove wrong buffer size check and add it in vimc_cap_buffer_prepare
>> - vimc_cap_create: remove unecessary check if v4l2_dev or v4l2_dev->dev is null
>> - vimc_cap_create: only allow a single pad
>> - vimc_sen_create: only allow source pads, remove unecessary source pads
>> checks in vimc_thread_sen
>>
>> Changes since v3: fix rmmod crash and built-in compile
>> - Re-order unregister calls in vimc_device_unregister function (remove
>> rmmod issue)
>> - Call media_device_unregister_entity in vimc_raw_destroy
>> - Add depends on VIDEO_DEV && VIDEO_V4L2 and select VIDEOBUF2_VMALLOC
>> - Check *nplanes in queue_setup (this remove v4l2-compliance fail)
>> - Include <linux/kthread.h> in vimc-sensor.c
>> - Move include of <linux/slab.h> from vimc-core.c to vimc-core.h
>> - Generate 60 frames per sec instead of 1 in the sensor
>>
>> Changes since v2: update with current media master tree
>> - Add struct media_pipeline in vimc_cap_device
>> - Use vb2_v4l2_buffer instead of vb2_buffer
>> - Typos
>> - Remove usage of entity->type and use entity->function instead
>> - Remove fmt argument from queue setup
>> - Use ktime_get_ns instead of v4l2_get_timestamp
>> - Iterate over link's list using list_for_each_entry
>> - Use media_device_{init, cleanup}
>> - Use entity->use_count to keep track of entities instead of the old
>> entity->id
>> - Replace media_entity_init by media_entity_pads_init
>> ---
>>  drivers/media/platform/Kconfig             |   2 +
>>  drivers/media/platform/Makefile            |   1 +
>>  drivers/media/platform/vimc/Kconfig        |   7 +
>>  drivers/media/platform/vimc/Makefile       |   3 +
>>  drivers/media/platform/vimc/vimc-capture.c | 553 ++++++++++++++++++++++++++
>>  drivers/media/platform/vimc/vimc-capture.h |  28 ++
>>  drivers/media/platform/vimc/vimc-core.c    | 600 +++++++++++++++++++++++++++++
>>  drivers/media/platform/vimc/vimc-core.h    |  57 +++
>>  drivers/media/platform/vimc/vimc-sensor.c  | 279 ++++++++++++++
>>  drivers/media/platform/vimc/vimc-sensor.h  |  28 ++
>>  10 files changed, 1558 insertions(+)
>>  create mode 100644 drivers/media/platform/vimc/Kconfig
>>  create mode 100644 drivers/media/platform/vimc/Makefile
>>  create mode 100644 drivers/media/platform/vimc/vimc-capture.c
>>  create mode 100644 drivers/media/platform/vimc/vimc-capture.h
>>  create mode 100644 drivers/media/platform/vimc/vimc-core.c
>>  create mode 100644 drivers/media/platform/vimc/vimc-core.h
>>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.c
>>  create mode 100644 drivers/media/platform/vimc/vimc-sensor.h
>>
>> diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
>> index 46f14dd..4a0577f 100644
>> --- a/drivers/media/platform/Kconfig
>> +++ b/drivers/media/platform/Kconfig
>> @@ -329,6 +329,8 @@ menuconfig V4L_TEST_DRIVERS
>>
>>  if V4L_TEST_DRIVERS
>>
>> +source "drivers/media/platform/vimc/Kconfig"
>> +
>>  source "drivers/media/platform/vivid/Kconfig"
>>
>>  config VIDEO_VIM2M
>> diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
>> index 536d1d8..dd4f658 100644
>> --- a/drivers/media/platform/Makefile
>> +++ b/drivers/media/platform/Makefile
>> @@ -12,6 +12,7 @@ obj-$(CONFIG_VIDEO_OMAP3)	+= omap3isp/
>>
>>  obj-$(CONFIG_VIDEO_VIU) += fsl-viu.o
>>
>> +obj-$(CONFIG_VIDEO_VIMC)		+= vimc/
>>  obj-$(CONFIG_VIDEO_VIVID)		+= vivid/
>>  obj-$(CONFIG_VIDEO_VIM2M)		+= vim2m.o
>>
>> diff --git a/drivers/media/platform/vimc/Kconfig b/drivers/media/platform/vimc/Kconfig
>> new file mode 100644
>> index 0000000..b48819c
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/Kconfig
>> @@ -0,0 +1,7 @@
>> +config VIDEO_VIMC
>> +	tristate "Virtual Media Controller Driver (VIMC)"
>> +	depends on VIDEO_DEV && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
>> +	select VIDEOBUF2_VMALLOC
>> +	default n
>> +	---help---
>> +	  Skeleton driver for Virtual Media Controller
>
> A bit more verbose description would be nice.
>
>> diff --git a/drivers/media/platform/vimc/Makefile b/drivers/media/platform/vimc/Makefile
>> new file mode 100644
>> index 0000000..c45195e
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/Makefile
>> @@ -0,0 +1,3 @@
>> +vimc-objs := vimc-core.o vimc-capture.o vimc-sensor.o
>> +
>> +obj-$(CONFIG_VIDEO_VIMC) += vimc.o
>> diff --git a/drivers/media/platform/vimc/vimc-capture.c b/drivers/media/platform/vimc/vimc-capture.c
>> new file mode 100644
>> index 0000000..b7636cf
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-capture.c
>> @@ -0,0 +1,553 @@
>> +/*
>> + * vimc-capture.c Virtual Media Controller Driver
>> + *
>> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
>
> 2017 might be used now.
>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#include <media/videobuf2-core.h>
>> +#include <media/videobuf2-vmalloc.h>
>> +#include <media/v4l2-ioctl.h>
>
> Numbers come before letters.
>
>> +
>> +#include "vimc-capture.h"
>> +
>> +struct vimc_cap_device {
>> +	struct vimc_ent_device ved;
>> +	struct video_device vdev;
>> +	struct v4l2_device *v4l2_dev;
>
> struct video_device also has a pointer to v4l2_dev. I wonder if that could
> be used.
>
>> +	struct device *dev;
>> +	struct v4l2_pix_format format;
>> +	struct vb2_queue queue;
>> +	struct list_head buf_list;
>> +	/*
>> +	 * NOTE: in a real driver, a spin lock must be used to access the
>> +	 * queue because the frames are generated from a hardware interruption
>> +	 * and the isr is not allowed to sleep.
>> +	 * Even if it is not necessary a spinlock in the vimc driver, we
>> +	 * use it here as a code reference
>> +	 */
>> +	spinlock_t qlock;
>> +	struct mutex lock;
>> +	u32 sequence;
>> +	struct media_pipeline pipe;
>> +};
>> +
>> +struct vimc_cap_buffer {
>> +	/*
>> +	 * vb2_buffer must be the first element
>
> vb2 or struct vb2_v4l2_buffer ?
>
>> +	 * the videobuf2 framework will allocate this struct based on
>> +	 * buf_struct_size and use the first sizeof(struct vb2_buffer) bytes of
>> +	 * memory as a vb2_buffer
>> +	 */
>> +	struct vb2_v4l2_buffer vb2;
>> +	struct list_head list;
>> +};
>> +
>> +static int vimc_cap_querycap(struct file *file, void *priv,
>> +			     struct v4l2_capability *cap)
>> +{
>> +	struct vimc_cap_device *vcap = video_drvdata(file);
>> +
>> +	strlcpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
>> +	strlcpy(cap->card, KBUILD_MODNAME, sizeof(cap->card));
>> +	snprintf(cap->bus_info, sizeof(cap->bus_info),
>> +		 "platform:%s", vcap->v4l2_dev->name);
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_cap_enum_input(struct file *file, void *priv,
>> +			       struct v4l2_input *i)
>> +{
>> +	/* We only have one input */
>> +	if (i->index > 0)
>> +		return -EINVAL;
>> +
>> +	i->type = V4L2_INPUT_TYPE_CAMERA;
>> +	strlcpy(i->name, "VIMC capture", sizeof(i->name));
>
> Isn't this (*INPUT IOCTLs) something that should be handled in a sub-device
> driver, such as a TV tuner?


Can the ioctl VIDIOC_ENUMINPUT enumerate no inputs at all? Can I just 
return -EINVAL here in G_INPUT and S_INPUT as well?
I thought I had to enumerate at least one input, and between 
V4L2_INPUT_TYPE_TUNER and V4L2_INPUT_TYPE_CAMERA, this last
one seems more appropriated


>
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_cap_g_input(struct file *file, void *priv, unsigned int *i)
>> +{
>> +	/* We only have one input */
>> +	*i = 0;
>> +	return 0;
>> +}
>> +
>> +static int vimc_cap_s_input(struct file *file, void *priv, unsigned int i)
>> +{
>> +	/* We only have one input */
>> +	return i ? -EINVAL : 0;
>> +}
>> +
>> +static int vimc_cap_fmt_vid_cap(struct file *file, void *priv,
>> +				  struct v4l2_format *f)
>> +{
>> +	struct vimc_cap_device *vcap = video_drvdata(file);
>> +
>> +	f->fmt.pix = vcap->format;
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_cap_enum_fmt_vid_cap(struct file *file, void *priv,
>> +				     struct v4l2_fmtdesc *f)
>> +{
>> +	struct vimc_cap_device *vcap = video_drvdata(file);
>> +
>> +	if (f->index > 0)
>> +		return -EINVAL;
>> +
>> +	/* We only support one format for now */
>> +	f->pixelformat = vcap->format.pixelformat;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct v4l2_file_operations vimc_cap_fops = {
>> +	.owner		= THIS_MODULE,
>> +	.open		= v4l2_fh_open,
>> +	.release	= vb2_fop_release,
>> +	.read           = vb2_fop_read,
>> +	.poll		= vb2_fop_poll,
>> +	.unlocked_ioctl = video_ioctl2,
>> +	.mmap           = vb2_fop_mmap,
>> +};
>> +
>> +static const struct v4l2_ioctl_ops vimc_cap_ioctl_ops = {
>> +	.vidioc_querycap = vimc_cap_querycap,
>> +
>> +	.vidioc_enum_input = vimc_cap_enum_input,
>> +	.vidioc_g_input = vimc_cap_g_input,
>> +	.vidioc_s_input = vimc_cap_s_input,
>> +
>> +	.vidioc_g_fmt_vid_cap = vimc_cap_fmt_vid_cap,
>> +	.vidioc_s_fmt_vid_cap = vimc_cap_fmt_vid_cap,
>> +	.vidioc_try_fmt_vid_cap = vimc_cap_fmt_vid_cap,
>> +	.vidioc_enum_fmt_vid_cap = vimc_cap_enum_fmt_vid_cap,
>> +
>> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
>> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
>> +	.vidioc_querybuf = vb2_ioctl_querybuf,
>> +	.vidioc_qbuf = vb2_ioctl_qbuf,
>> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
>> +	.vidioc_expbuf = vb2_ioctl_expbuf,
>> +	.vidioc_streamon = vb2_ioctl_streamon,
>> +	.vidioc_streamoff = vb2_ioctl_streamoff,
>> +};
>> +
>> +static void vimc_cap_return_all_buffers(struct vimc_cap_device *vcap,
>> +					enum vb2_buffer_state state)
>> +{
>> +	struct vimc_cap_buffer *vbuf, *node;
>> +
>> +	spin_lock(&vcap->qlock);
>> +
>> +	list_for_each_entry_safe(vbuf, node, &vcap->buf_list, list) {
>> +		vb2_buffer_done(&vbuf->vb2.vb2_buf, state);
>> +		list_del(&vbuf->list);
>> +	}
>> +
>> +	spin_unlock(&vcap->qlock);
>> +}
>> +
>> +static int vimc_cap_pipeline_s_stream(struct vimc_cap_device *vcap, int enable)
>> +{
>> +	int ret;
>> +	struct media_pad *pad;
>> +	struct media_entity *entity;
>> +	struct v4l2_subdev *sd;
>> +
>> +	/* Start the stream in the subdevice direct connected */
>> +	entity = &vcap->vdev.entity;
>> +	pad = media_entity_remote_pad(&entity->pads[0]);
>
> You could use vcap->vdev.entity.pads here, without assigning to entity. Then
> entity would only be used to refer to the remove entity at the other end of
> the link. Up to you.
>
>> +
>> +	/* If we are not connected to any subdev node, it means there is nothing
>
> /*
>  * Multi line
>  * comment.
>  */
>
>> +	 * to activate on the pipe (e.g. we can be connected with an input
>> +	 * device or we are not connected at all)
>> +	 */
>> +	if (pad == NULL || !is_media_entity_v4l2_subdev(pad->entity))
>> +		return 0;
>> +
>> +	entity = pad->entity;
>> +	sd = media_entity_to_v4l2_subdev(entity);
>
> And if you used pad->entity here, you could remove the entity variable
> altogether.
>
>> +
>> +	ret = v4l2_subdev_call(sd, video, s_stream, enable);
>> +	if (ret && ret != -ENOIOCTLCMD)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int count)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>> +	struct media_entity *entity;
>> +	int ret;
>> +
>> +	vcap->sequence = 0;
>> +
>> +	/* Start the media pipeline */
>> +	entity = &vcap->vdev.entity;
>> +	ret = media_entity_pipeline_start(entity, &vcap->pipe);
>> +	if (ret) {
>> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
>> +		return ret;
>> +	}
>> +
>> +	/* Enable streaming from the pipe */
>> +	ret = vimc_cap_pipeline_s_stream(vcap, 1);
>> +	if (ret) {
>> +		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Stop the stream engine. Any remaining buffers in the stream queue are
>> + * dequeued and passed on to the vb2 framework marked as STATE_ERROR.
>> + */
>> +static void vimc_cap_stop_streaming(struct vb2_queue *vq)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>> +
>> +	/* Disable streaming from the pipe */
>> +	vimc_cap_pipeline_s_stream(vcap, 0);
>> +
>> +	/* Stop the media pipeline */
>> +	media_entity_pipeline_stop(&vcap->vdev.entity);
>> +
>> +	/* Release all active buffers */
>> +	vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_ERROR);
>> +}
>> +
>> +static void vimc_cap_buf_queue(struct vb2_buffer *vb2_buf)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb2_buf->vb2_queue);
>> +	struct vimc_cap_buffer *buf = container_of(vb2_buf,
>> +						   struct vimc_cap_buffer,
>> +						   vb2.vb2_buf);
>> +
>> +	spin_lock(&vcap->qlock);
>> +	list_add_tail(&buf->list, &vcap->buf_list);
>> +	spin_unlock(&vcap->qlock);
>> +}
>> +
>> +static int vimc_cap_queue_setup(struct vb2_queue *vq, unsigned int *nbuffers,
>> +				unsigned int *nplanes, unsigned int sizes[],
>> +				struct device *alloc_devs[])
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>> +
>> +	if (*nplanes)
>> +		return sizes[0] < vcap->format.sizeimage ? -EINVAL : 0;
>
> Why? The user could later reconfigure the device to use with a buffer of
> this size. This might not be a concern for vimc, but the code from example
> drivers tends to get copied around.


This first version only support a fixed sizeimage, this will be changed 
in the next patch series where
I add support for multiple sizes


>
>> +	/* We don't support multiplanes for now */
>> +	*nplanes = 1;
>> +	sizes[0] = vcap->format.sizeimage;
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Prepare the buffer for queueing to the DMA engine: check and set the
>> + * payload size.
>> + */
>> +static int vimc_cap_buffer_prepare(struct vb2_buffer *vb)
>> +{
>> +	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb->vb2_queue);
>> +	unsigned long size = vcap->format.sizeimage;
>> +
>> +	if (vb2_plane_size(vb, 0) < size) {
>> +		dev_err(vcap->dev, "buffer too small (%lu < %lu)\n",
>> +			vb2_plane_size(vb, 0), size);
>> +		return -EINVAL;
>> +	}
>> +
>> +	vb2_set_plane_payload(vb, 0, size);
>
> Newline here?
>
>> +	return 0;
>> +}
>> +
>> +static const struct vb2_ops vimc_cap_qops = {
>> +	.start_streaming	= vimc_cap_start_streaming,
>> +	.stop_streaming		= vimc_cap_stop_streaming,
>> +	.buf_queue		= vimc_cap_buf_queue,
>> +	.queue_setup		= vimc_cap_queue_setup,
>> +	.buf_prepare		= vimc_cap_buffer_prepare,
>> +	/*
>> +	 * Since q->lock is set we can use the standard
>> +	 * vb2_ops_wait_prepare/finish helper functions.
>> +	 */
>> +	.wait_prepare		= vb2_ops_wait_prepare,
>> +	.wait_finish		= vb2_ops_wait_finish,
>> +};
>> +
>
>> +/* NOTE: this function is a copy of v4l2_subdev_link_validate_get_format
>
> /*
>  * ...
>
>> + * maybe the v4l2 function should be public
>> + */
>> +static int vimc_cap_v4l2_subdev_link_validate_get_format(struct media_pad *pad,
>> +						struct v4l2_subdev_format *fmt)
>> +{
>> +	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(pad->entity);
>> +
>> +	fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
>> +	fmt->pad = pad->index;
>
> A newline here would be nice.
>
>> +	return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);
>> +}
>> +
>> +static int vimc_cap_link_validate(struct media_link *link)
>> +{
>> +	struct v4l2_subdev_format source_fmt;
>> +	struct v4l2_pix_format *sink_fmt;
>> +	struct vimc_cap_device *vcap;
>> +	const struct vimc_pix_map *vpix;
>> +	int ret;
>> +
>> +	/* Retrieve the video capture device */
>> +	vcap = container_of(link->sink->entity,
>> +			    struct vimc_cap_device, vdev.entity);
>
> You could assign in variable declaration.
>
>> +
>> +	/* If the connected node is not a subdevice type
>
> Ditto.
>
>> +	 * then it's a raw node from vimc-core, ignore the link for now
>
> What's a raw node in this case?
>


It's a dummy node created in vimc-core.c just to fill gaps in the 
topology in the place of other future nodes as
scaler, input, debayer filter that are not yet present.


>> +	 * TODO: remove this when there are no more raw nodes in the
>> +	 * core and return error instead
>> +	 */
>> +	if (!is_media_entity_v4l2_subdev(link->source->entity))
>> +		return 0;
>> +
>> +	/* Get the the format of the video device */
>> +	sink_fmt = &vcap->format;
>
> Same for sink_fmt, you could assign it in variable declaration.
>
>> +
>> +	/* Get the the format of the subdev */
>> +	ret = vimc_cap_v4l2_subdev_link_validate_get_format(link->source,
>> +							    &source_fmt);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev_dbg(vcap->dev,
>> +		"cap: %s: link validate formats src:%dx%d %d sink:%dx%d %d\n",
>> +		vcap->vdev.name,
>> +		source_fmt.format.width, source_fmt.format.height,
>> +		source_fmt.format.code,
>> +		sink_fmt->width, sink_fmt->height,
>> +		sink_fmt->pixelformat);
>> +
>> +	/* Validate the format */
>> +
>> +	vpix = vimc_pix_map_by_pixelformat(sink_fmt->pixelformat);
>> +	if (!vpix)
>> +		return -EINVAL;
>> +
>> +	/* The width, height and code must match. */
>> +	if (source_fmt.format.width != sink_fmt->width
>> +	    || source_fmt.format.height != sink_fmt->height
>> +	    || vpix->code != source_fmt.format.code)
>> +		return -EINVAL;
>> +
>> +	/* The field order must match, or the sink field order must be NONE
>> +	 * to support interlaced hardware connected to bridges that support
>> +	 * progressive formats only.
>> +	 */
>> +	if (source_fmt.format.field != sink_fmt->field &&
>> +	    sink_fmt->field != V4L2_FIELD_NONE)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct media_entity_operations vimc_cap_mops = {
>> +	.link_validate		= vimc_cap_link_validate,
>> +};
>> +
>> +static void vimc_cap_destroy(struct vimc_ent_device *ved)
>> +{
>> +	struct vimc_cap_device *vcap = container_of(ved, struct vimc_cap_device,
>> +						    ved);
>> +
>> +	vb2_queue_release(&vcap->queue);
>> +	media_entity_cleanup(ved->ent);
>> +	video_unregister_device(&vcap->vdev);
>> +	vimc_pads_cleanup(vcap->ved.pads);
>> +	kfree(vcap);
>> +}
>> +
>> +static void vimc_cap_process_frame(struct vimc_ent_device *ved,
>> +				   struct media_pad *sink, const void *frame)
>> +{
>> +	struct vimc_cap_device *vcap = container_of(ved, struct vimc_cap_device,
>> +						    ved);
>> +	struct vimc_cap_buffer *vimc_buf;
>> +	void *vbuf;
>> +
>> +	/* If the stream in this node is not active, just return */
>> +	mutex_lock(&vcap->lock);
>> +	if (!vb2_is_busy(&vcap->queue)) {
>> +		mutex_unlock(&vcap->lock);
>> +		return;
>> +	}
>> +	mutex_unlock(&vcap->lock);
>> +
>> +	spin_lock(&vcap->qlock);
>> +
>> +	/* Get the first entry of the list */
>> +	vimc_buf = list_first_entry_or_null(&vcap->buf_list,
>> +					    typeof(*vimc_buf), list);
>> +	if (!vimc_buf) {
>> +		spin_unlock(&vcap->qlock);
>> +		return;
>> +	}
>> +
>> +	/* Remove this entry from the list */
>> +	list_del(&vimc_buf->list);
>> +
>> +	spin_unlock(&vcap->qlock);
>> +
>> +	/* Fill the buffer */
>> +	vimc_buf->vb2.vb2_buf.timestamp = ktime_get_ns();
>> +	vimc_buf->vb2.sequence = vcap->sequence++;
>> +	vimc_buf->vb2.field = vcap->format.field;
>> +
>> +	vbuf = vb2_plane_vaddr(&vimc_buf->vb2.vb2_buf, 0);
>> +
>> +	memcpy(vbuf, frame, vcap->format.sizeimage);
>> +
>> +	/* Set it as ready */
>> +	vb2_set_plane_payload(&vimc_buf->vb2.vb2_buf, 0,
>> +			      vcap->format.sizeimage);
>> +	vb2_buffer_done(&vimc_buf->vb2.vb2_buf, VB2_BUF_STATE_DONE);
>> +}
>> +
>> +struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
>> +					const char *const name,
>> +					u16 num_pads,
>> +					const unsigned long *pads_flag)
>> +{
>> +	int ret;
>
> It'd be nice to declare temporary variables, return values and such last.
>
>> +	struct vb2_queue *q;
>> +	struct video_device *vdev;
>> +	struct vimc_cap_device *vcap;
>> +	const struct vimc_pix_map *vpix;
>> +
>> +	/* Check entity configuration params
>
> /*
>  *
>
>> +	 * NOTE: we only support a single sink pad
>> +	 */
>> +	if (!name || num_pads != 1 || !pads_flag ||
>> +	    !(pads_flag[0] & MEDIA_PAD_FL_SINK))
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	/* Allocate the vimc_cap_device struct */
>> +	vcap = kzalloc(sizeof(*vcap), GFP_KERNEL);
>> +	if (!vcap)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* Link the vimc_cap_device struct with v4l2 and dev parent */
>> +	vcap->v4l2_dev = v4l2_dev;
>> +	vcap->dev = v4l2_dev->dev;
>> +
>> +	/* Allocate the pads */
>> +	vcap->ved.pads = vimc_pads_init(num_pads, pads_flag);
>> +	if (IS_ERR(vcap->ved.pads)) {
>> +		ret = PTR_ERR(vcap->ved.pads);
>> +		goto err_free_vcap;
>> +	}
>> +
>> +	/* Initialize the media entity */
>> +	vcap->vdev.entity.name = name;
>> +	vcap->vdev.entity.function = MEDIA_ENT_F_IO_V4L;
>> +	ret = media_entity_pads_init(&vcap->vdev.entity,
>> +				     num_pads, vcap->ved.pads);
>> +	if (ret)
>> +		goto err_clean_pads;
>> +
>> +	/* Initialize the lock */
>> +	mutex_init(&vcap->lock);
>> +
>> +	/* Initialize the vb2 queue */
>> +	q = &vcap->queue;
>> +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>> +	q->io_modes = VB2_MMAP | VB2_DMABUF;
>> +	q->drv_priv = vcap;
>> +	q->buf_struct_size = sizeof(struct vimc_cap_buffer);
>> +	q->ops = &vimc_cap_qops;
>> +	q->mem_ops = &vb2_vmalloc_memops;
>> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
>> +	q->min_buffers_needed = 2;
>> +	q->lock = &vcap->lock;
>> +
>> +	ret = vb2_queue_init(q);
>> +	if (ret) {
>> +		dev_err(vcap->dev,
>> +			"vb2 queue init failed (err=%d)\n", ret);
>> +		goto err_clean_m_ent;
>> +	}
>> +
>> +	/* Initialize buffer list and its lock */
>> +	INIT_LIST_HEAD(&vcap->buf_list);
>> +	spin_lock_init(&vcap->qlock);
>> +
>> +	/* Set the frame format (this is hardcoded for now) */
>> +	vcap->format.width = 640;
>> +	vcap->format.height = 480;
>> +	vcap->format.pixelformat = V4L2_PIX_FMT_RGB24;
>> +	vcap->format.field = V4L2_FIELD_NONE;
>> +	vcap->format.colorspace = V4L2_COLORSPACE_SRGB;
>> +
>> +	vpix = vimc_pix_map_by_pixelformat(vcap->format.pixelformat);
>> +
>> +	vcap->format.bytesperline = vcap->format.width * vpix->bpp;
>> +	vcap->format.sizeimage = vcap->format.bytesperline *
>> +				 vcap->format.height;
>> +
>> +	/* Fill the vimc_ent_device struct */
>> +	vcap->ved.destroy = vimc_cap_destroy;
>> +	vcap->ved.ent = &vcap->vdev.entity;
>> +	vcap->ved.process_frame = vimc_cap_process_frame;
>> +
>> +	/* Initialize the video_device struct */
>> +	vdev = &vcap->vdev;
>> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
>> +	vdev->entity.ops = &vimc_cap_mops;
>> +	vdev->release = video_device_release_empty;
>> +	vdev->fops = &vimc_cap_fops;
>> +	vdev->ioctl_ops = &vimc_cap_ioctl_ops;
>> +	vdev->lock = &vcap->lock;
>> +	vdev->queue = q;
>> +	vdev->v4l2_dev = vcap->v4l2_dev;
>> +	vdev->vfl_dir = VFL_DIR_RX;
>> +	strlcpy(vdev->name, name, sizeof(vdev->name));
>> +	video_set_drvdata(vdev, vcap);
>> +
>> +	/* Register the video_device with the v4l2 and the media framework */
>> +	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
>> +	if (ret) {
>> +		dev_err(vcap->dev,
>> +			"video register failed (err=%d)\n", ret);
>> +		goto err_release_queue;
>> +	}
>> +
>> +	return &vcap->ved;
>> +
>> +err_release_queue:
>> +	vb2_queue_release(q);
>> +err_clean_m_ent:
>> +	media_entity_cleanup(&vcap->vdev.entity);
>> +err_clean_pads:
>> +	vimc_pads_cleanup(vcap->ved.pads);
>> +err_free_vcap:
>> +	kfree(vcap);
>> +
>> +	return ERR_PTR(ret);
>> +}
>> diff --git a/drivers/media/platform/vimc/vimc-capture.h b/drivers/media/platform/vimc/vimc-capture.h
>> new file mode 100644
>> index 0000000..bcf9fc37
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-capture.h
>> @@ -0,0 +1,28 @@
>> +/*
>> + * vimc-capture.h Virtual Media Controller Driver
>> + *
>> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#ifndef _VIMC_CAPTURE_H_
>> +#define _VIMC_CAPTURE_H_
>> +
>> +#include "vimc-core.h"
>> +
>> +struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
>> +					const char *const name,
>> +					u16 num_pads,
>> +					const unsigned long *pads_flag);
>> +
>> +#endif
>> diff --git a/drivers/media/platform/vimc/vimc-core.c b/drivers/media/platform/vimc/vimc-core.c
>> new file mode 100644
>> index 0000000..0a2b91b
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-core.c
>> @@ -0,0 +1,600 @@
>> +/*
>> + * vimc-core.c Virtual Media Controller Driver
>> + *
>> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#include <linux/init.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <media/media-device.h>
>> +#include <media/v4l2-device.h>
>> +
>> +#include "vimc-capture.h"
>> +#include "vimc-core.h"
>> +#include "vimc-sensor.h"
>> +
>> +#define VIMC_PDEV_NAME "vimc"
>> +#define VIMC_MDEV_MODEL_NAME "VIMC MDEV"
>> +
>> +#define VIMC_ENT_LINK(src, srcpad, sink, sinkpad, link_flags) {	\
>> +	.src_ent = src,						\
>> +	.src_pad = srcpad,					\
>> +	.sink_ent = sink,					\
>> +	.sink_pad = sinkpad,					\
>> +	.flags = link_flags,					\
>> +}
>> +
>> +#define VIMC_PIX_MAP(_code, _bpp, _pixelformat) {	\
>> +	.code = _code,					\
>> +	.pixelformat = _pixelformat,			\
>> +	.bpp = _bpp,					\
>> +}
>> +
>> +struct vimc_device {
>> +	/* The pipeline configuration
>
> /*
>  *
>
>> +	 * (filled before calling vimc_device_register)
>> +	 */
>> +	const struct vimc_pipeline_config *pipe_cfg;
>> +
>> +	/* The Associated media_device parent */
>> +	struct media_device mdev;
>> +
>> +	/* Internal v4l2 parent device*/
>> +	struct v4l2_device v4l2_dev;
>> +
>> +	/* Internal topology */
>> +	struct vimc_ent_device **ved;
>> +};
>> +
>> +/**
>> + * enum vimc_ent_node - Select the functionality of a node in the topology
>> + * @VIMC_ENT_NODE_SENSOR:	A node of type SENSOR simulates a camera sensor
>> + *				generating internal images in bayer format and
>> + *				propagating those images through the pipeline
>> + * @VIMC_ENT_NODE_CAPTURE:	A node of type CAPTURE is a v4l2 video_device
>> + *				that exposes the received image from the
>> + *				pipeline to the user space
>> + * @VIMC_ENT_NODE_INPUT:	A node of type INPUT is a v4l2 video_device that
>> + *				receives images from the user space and
>> + *				propagates them through the pipeline
>> + * @VIMC_ENT_NODE_DEBAYER:	A node type DEBAYER expects to receive a frame
>> + *				in bayer format converts it to RGB
>> + * @VIMC_ENT_NODE_SCALER:	A node of type SCALER scales the received image
>> + *				by a given multiplier
>> + *
>> + * This enum is used in the entity configuration struct to allow the definition
>> + * of a custom topology specifying the role of each node on it.
>> + */
>> +enum vimc_ent_node {
>> +	VIMC_ENT_NODE_SENSOR,
>> +	VIMC_ENT_NODE_CAPTURE,
>> +	VIMC_ENT_NODE_INPUT,
>> +	VIMC_ENT_NODE_DEBAYER,
>> +	VIMC_ENT_NODE_SCALER,
>> +};
>> +
>> +/* Structure which describes individual configuration for each entity */
>> +struct vimc_ent_config {
>> +	const char *name;
>> +	size_t pads_qty;
>> +	const unsigned long *pads_flag;
>> +	enum vimc_ent_node node;
>> +};
>> +
>> +/* Structure which describes links between entities */
>> +struct vimc_ent_link {
>> +	unsigned int src_ent;
>> +	u16 src_pad;
>> +	unsigned int sink_ent;
>> +	u16 sink_pad;
>> +	u32 flags;
>> +};
>> +
>> +/* Structure which describes the whole topology */
>> +struct vimc_pipeline_config {
>> +	const struct vimc_ent_config *ents;
>> +	size_t num_ents;
>> +	const struct vimc_ent_link *links;
>> +	size_t num_links;
>> +};
>> +
>> +/* --------------------------------------------------------------------------
>> + * Topology Configuration
>> + */
>> +
>> +static const struct vimc_ent_config ent_config[] = {
>> +	{
>> +		.name = "Sensor A",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_SENSOR,
>> +	},
>> +	{
>> +		.name = "Sensor B",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_SENSOR,
>> +	},
>> +	{
>> +		.name = "Debayer A",
>> +		.pads_qty = 2,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
>> +						     MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_DEBAYER,
>> +	},
>> +	{
>> +		.name = "Debayer B",
>> +		.pads_qty = 2,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
>> +						     MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_DEBAYER,
>> +	},
>> +	{
>> +		.name = "Raw Capture 0",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
>> +		.node = VIMC_ENT_NODE_CAPTURE,
>> +	},
>> +	{
>> +		.name = "Raw Capture 1",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
>> +		.node = VIMC_ENT_NODE_CAPTURE,
>> +	},
>> +	{
>> +		.name = "RGB/YUV Input",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_INPUT,
>> +	},
>> +	{
>> +		.name = "Scaler",
>> +		.pads_qty = 2,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
>> +						     MEDIA_PAD_FL_SOURCE},
>> +		.node = VIMC_ENT_NODE_SCALER,
>> +	},
>> +	{
>> +		.name = "RGB/YUV Capture",
>> +		.pads_qty = 1,
>> +		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
>> +		.node = VIMC_ENT_NODE_CAPTURE,
>> +	},
>> +};
>> +
>> +static const struct vimc_ent_link ent_links[] = {
>> +	/* Link: Sensor A (Pad 0)->(Pad 0) Debayer A */
>> +	VIMC_ENT_LINK(0, 0, 2, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Sensor A (Pad 0)->(Pad 0) Raw Capture 0 */
>> +	VIMC_ENT_LINK(0, 0, 4, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Sensor B (Pad 0)->(Pad 0) Debayer B */
>> +	VIMC_ENT_LINK(1, 0, 3, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Sensor B (Pad 0)->(Pad 0) Raw Capture 1 */
>> +	VIMC_ENT_LINK(1, 0, 5, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
>> +	/* Link: Debayer A (Pad 1)->(Pad 0) Scaler */
>> +	VIMC_ENT_LINK(2, 1, 7, 0, MEDIA_LNK_FL_ENABLED),
>> +	/* Link: Debayer B (Pad 1)->(Pad 0) Scaler */
>> +	VIMC_ENT_LINK(3, 1, 7, 0, 0),
>> +	/* Link: RGB/YUV Input (Pad 0)->(Pad 0) Scaler */
>> +	VIMC_ENT_LINK(6, 0, 7, 0, 0),
>> +	/* Link: Scaler (Pad 1)->(Pad 0) RGB/YUV Capture */
>> +	VIMC_ENT_LINK(7, 1, 8, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
>> +};
>> +
>> +static const struct vimc_pipeline_config pipe_cfg = {
>> +	.ents		= ent_config,
>> +	.num_ents	= ARRAY_SIZE(ent_config),
>> +	.links		= ent_links,
>> +	.num_links	= ARRAY_SIZE(ent_links)
>> +};
>> +
>> +/* -------------------------------------------------------------------------- */
>> +
>> +static void vimc_dev_release(struct device *dev)
>> +{}
>> +
>> +static struct platform_device vimc_pdev = {
>> +	.name		= VIMC_PDEV_NAME,
>> +	.dev.release	= vimc_dev_release,
>> +};
>> +
>> +const struct vimc_pix_map vimc_pix_map_list[] = {
>> +	/* TODO: add all missing formats */
>> +
>> +	/* RGB formats */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_BGR888_1X24, 3, V4L2_PIX_FMT_BGR24),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_RGB888_1X24, 3, V4L2_PIX_FMT_RGB24),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_ARGB8888_1X32, 4, V4L2_PIX_FMT_ARGB32),
>> +
>> +	/* Bayer formats */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR8_1X8, 1, V4L2_PIX_FMT_SBGGR8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG8_1X8, 1, V4L2_PIX_FMT_SGBRG8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG8_1X8, 1, V4L2_PIX_FMT_SGRBG8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB8_1X8, 1, V4L2_PIX_FMT_SRGGB8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_1X10, 2, V4L2_PIX_FMT_SBGGR10),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_1X10, 2, V4L2_PIX_FMT_SGBRG10),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_1X10, 2, V4L2_PIX_FMT_SGRBG10),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_1X10, 2, V4L2_PIX_FMT_SRGGB10),
>> +	/* 10bit raw bayer a-law compressed to 8 bits */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_ALAW8_1X8, 1, V4L2_PIX_FMT_SBGGR10ALAW8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGBRG10ALAW8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGRBG10ALAW8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_ALAW8_1X8, 1, V4L2_PIX_FMT_SRGGB10ALAW8),
>> +	/* 10bit raw bayer DPCM compressed to 8 bits */
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_DPCM8_1X8, 1, V4L2_PIX_FMT_SBGGR10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGBRG10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGRBG10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_DPCM8_1X8, 1, V4L2_PIX_FMT_SRGGB10DPCM8),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR12_1X12, 2, V4L2_PIX_FMT_SBGGR12),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG12_1X12, 2, V4L2_PIX_FMT_SGBRG12),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG12_1X12, 2, V4L2_PIX_FMT_SGRBG12),
>> +	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB12_1X12, 2, V4L2_PIX_FMT_SRGGB12),
>> +
>> +	/* End */
>> +	{0, 0, 0}
>> +};
>> +
>> +const struct vimc_pix_map *vimc_pix_map_by_code(u32 code)
>> +{
>> +	unsigned int i;
>> +
>> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
>> +		if (vimc_pix_map_list[i].code == code)
>> +			return &vimc_pix_map_list[i];
>> +	}
>> +	return NULL;
>> +}
>> +
>> +const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat)
>> +{
>> +	unsigned int i;
>> +
>> +	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
>> +		if (vimc_pix_map_list[i].pixelformat == pixelformat)
>> +			return &vimc_pix_map_list[i];
>> +	}
>> +	return NULL;
>> +}
>> +
>> +int vimc_propagate_frame(struct device *dev,
>> +			 struct media_pad *src, const void *frame)
>> +{
>> +	struct media_link *link;
>> +	struct vimc_device *vimc = dev_get_drvdata(dev);
>> +
>> +	if (!(src->flags & MEDIA_PAD_FL_SOURCE))
>> +		return -EINVAL;
>> +
>> +	/* Send this frame to all sink pads that are direct linked */
>> +	list_for_each_entry(link, &src->entity->links, list) {
>> +		if (link->source == src &&
>> +		    (link->flags & MEDIA_LNK_FL_ENABLED)) {
>> +			struct vimc_ent_device *ved;
>> +
>> +			ved = vimc->ved[link->sink->entity->use_count];
>> +			if (ved && ved->process_frame)
>> +				ved->process_frame(ved, link->sink, frame);
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void vimc_device_unregister(struct vimc_device *vimc)
>> +{
>> +	unsigned int i;
>> +
>> +	/* Cleanup (only initialized) entities */
>> +	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
>> +		if (vimc->ved[i] && vimc->ved[i]->destroy)
>> +			vimc->ved[i]->destroy(vimc->ved[i]);
>> +
>> +		vimc->ved[i] = NULL;
>> +	}
>> +	v4l2_device_unregister(&vimc->v4l2_dev);
>> +
>> +	media_device_unregister(&vimc->mdev);
>> +	media_device_cleanup(&vimc->mdev);
>> +}
>> +
>> +/* Helper function to allocate and initialize pads */
>> +struct media_pad *vimc_pads_init(u16 num_pads, const unsigned long *pads_flag)
>> +{
>> +	unsigned int i;
>> +	struct media_pad *pads;
>> +
>> +	/* Allocate memory for the pads */
>> +	pads = kcalloc(num_pads, sizeof(*pads), GFP_KERNEL);
>> +	if (!pads)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* Initialize the pads */
>> +	for (i = 0; i < num_pads; i++) {
>> +		pads[i].index = i;
>> +		pads[i].flags = pads_flag[i];
>> +	}
>> +
>> +	return pads;
>> +}
>> +
>> +/* TODO: remove this function when all the
>> + * entities specific code are implemented
>> + */
>> +static void vimc_raw_destroy(struct vimc_ent_device *ved)
>> +{
>> +	media_device_unregister_entity(ved->ent);
>> +
>> +	media_entity_cleanup(ved->ent);
>> +
>> +	vimc_pads_cleanup(ved->pads);
>> +
>> +	kfree(ved->ent);
>> +
>> +	kfree(ved);
>> +}
>> +
>> +/* TODO: remove this function when all the
>> + * entities specific code are implemented
>> + */
>> +static struct vimc_ent_device *vimc_raw_create(struct v4l2_device *v4l2_dev,
>> +					       const char *const name,
>> +					       u16 num_pads,
>> +					       const unsigned long *pads_flag)
>> +{
>> +	int ret;
>> +	struct vimc_ent_device *ved;
>> +
>> +	/* Allocate the main ved struct */
>> +	ved = kzalloc(sizeof(*ved), GFP_KERNEL);
>> +	if (!ved)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* Allocate the media entity */
>> +	ved->ent = kzalloc(sizeof(*ved->ent), GFP_KERNEL);
>> +	if (!ved->ent) {
>> +		ret = -ENOMEM;
>> +		goto err_free_ved;
>> +	}
>> +
>> +	/* Allocate the pads */
>> +	ved->pads = vimc_pads_init(num_pads, pads_flag);
>> +	if (IS_ERR(ved->pads)) {
>> +		ret = PTR_ERR(ved->pads);
>> +		goto err_free_ent;
>> +	}
>> +
>> +	/* Initialize the media entity */
>> +	ved->ent->name = name;
>> +	ved->ent->function = MEDIA_ENT_F_IO_V4L;
>> +	ret = media_entity_pads_init(ved->ent, num_pads, ved->pads);
>> +	if (ret)
>> +		goto err_cleanup_pads;
>> +
>> +	/* Register the media entity */
>> +	ret = media_device_register_entity(v4l2_dev->mdev, ved->ent);
>> +	if (ret)
>> +		goto err_cleanup_entity;
>> +
>> +	/* Fill out the destroy function and return */
>> +	ved->destroy = vimc_raw_destroy;
>> +	return ved;
>> +
>> +err_cleanup_entity:
>> +	media_entity_cleanup(ved->ent);
>> +err_cleanup_pads:
>> +	vimc_pads_cleanup(ved->pads);
>> +err_free_ent:
>> +	kfree(ved->ent);
>> +err_free_ved:
>> +	kfree(ved);
>> +
>> +	return ERR_PTR(ret);
>> +}
>> +
>> +static int vimc_device_register(struct vimc_device *vimc)
>> +{
>> +	unsigned int i;
>> +	int ret = 0;
>> +
>> +	/* Allocate memory for the vimc_ent_devices pointers */
>> +	vimc->ved = devm_kcalloc(vimc->mdev.dev, vimc->pipe_cfg->num_ents,
>> +				 sizeof(*vimc->ved), GFP_KERNEL);
>> +	if (!vimc->ved)
>> +		return -ENOMEM;
>> +
>> +	/* Register the media device */
>> +	ret = media_device_register(&vimc->mdev);
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"media device register failed (err=%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Link the media device within the v4l2_device */
>> +	vimc->v4l2_dev.mdev = &vimc->mdev;
>> +
>> +	/* Register the v4l2 struct */
>> +	ret = v4l2_device_register(vimc->mdev.dev, &vimc->v4l2_dev);
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"v4l2 device register failed (err=%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Initialize entities */
>> +	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
>> +		struct vimc_ent_device *(*create_func)(struct v4l2_device *,
>> +						       const char *const,
>> +						       u16,
>> +						       const unsigned long *);
>> +
>> +		/* Register the specific node */
>> +		switch (vimc->pipe_cfg->ents[i].node) {
>> +		case VIMC_ENT_NODE_SENSOR:
>> +			create_func = vimc_sen_create;
>> +			break;
>> +
>> +		case VIMC_ENT_NODE_CAPTURE:
>> +			create_func = vimc_cap_create;
>> +			break;
>> +
>> +		/* TODO: Instantiate the specific topology node */
>> +		case VIMC_ENT_NODE_INPUT:
>> +		case VIMC_ENT_NODE_DEBAYER:
>> +		case VIMC_ENT_NODE_SCALER:
>> +		default:
>> +			/* TODO: remove this when all the entities specific
>> +			 * code are implemented
>> +			 */
>> +			create_func = vimc_raw_create;
>> +			break;
>> +		}
>> +
>> +		vimc->ved[i] = create_func(&vimc->v4l2_dev,
>> +					   vimc->pipe_cfg->ents[i].name,
>> +					   vimc->pipe_cfg->ents[i].pads_qty,
>> +					   vimc->pipe_cfg->ents[i].pads_flag);
>> +		if (IS_ERR(vimc->ved[i])) {
>> +			ret = PTR_ERR(vimc->ved[i]);
>> +			vimc->ved[i] = NULL;
>> +			goto err;
>> +		}
>> +
>> +		/* Set use_count to keep track of the ved structure */
>> +		vimc->ved[i]->ent->use_count = i;
>> +	}
>> +
>> +	/* Initialize the links between entities */
>> +	for (i = 0; i < vimc->pipe_cfg->num_links; i++) {
>> +		const struct vimc_ent_link *link = &vimc->pipe_cfg->links[i];
>> +
>> +		ret = media_create_pad_link(vimc->ved[link->src_ent]->ent,
>> +					    link->src_pad,
>> +					    vimc->ved[link->sink_ent]->ent,
>> +					    link->sink_pad,
>> +					    link->flags);
>> +		if (ret)
>> +			goto err;
>> +	}
>> +
>> +	/* Expose all subdev's nodes*/
>> +	ret = v4l2_device_register_subdev_nodes(&vimc->v4l2_dev);
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"vimc subdev nodes registration failed (err=%d)\n",
>> +			ret);
>> +		goto err;
>> +	}
>> +
>> +	return 0;
>> +
>> +err:
>> +	/* Destroy the so far created topology */
>> +	vimc_device_unregister(vimc);
>> +
>> +	return ret;
>> +}
>> +
>> +static int vimc_probe(struct platform_device *pdev)
>> +{
>> +	struct vimc_device *vimc;
>> +	int ret;
>> +
>> +	/* Prepare the vimc topology structure */
>> +
>> +	/* Allocate memory for the vimc structure */
>> +	vimc = devm_kzalloc(&pdev->dev, sizeof(*vimc), GFP_KERNEL);
>> +	if (!vimc)
>> +		return -ENOMEM;
>> +
>> +	/* Set the pipeline configuration struct */
>> +	vimc->pipe_cfg = &pipe_cfg;
>> +
>> +	/* Initialize media device */
>> +	strlcpy(vimc->mdev.model, VIMC_MDEV_MODEL_NAME,
>> +		sizeof(vimc->mdev.model));
>> +	vimc->mdev.dev = &pdev->dev;
>> +	media_device_init(&vimc->mdev);
>> +
>> +	/* Create vimc topology */
>> +	ret = vimc_device_register(vimc);
>> +	if (ret) {
>> +		dev_err(vimc->mdev.dev,
>> +			"vimc device registration failed (err=%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Link the topology object with the platform device object */
>> +	platform_set_drvdata(pdev, vimc);
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_remove(struct platform_device *pdev)
>> +{
>> +	struct vimc_device *vimc;
>> +
>> +	/* Get the topology object linked with the platform device object */
>> +	vimc = platform_get_drvdata(pdev);
>
> You should assign in variable declaration.
>
>> +
>> +	/* Destroy all the topology */
>> +	vimc_device_unregister(vimc);
>> +
>> +	return 0;
>> +}
>> +
>> +static struct platform_driver vimc_pdrv = {
>> +	.probe		= vimc_probe,
>> +	.remove		= vimc_remove,
>> +	.driver		= {
>> +		.name	= VIMC_PDEV_NAME,
>> +	},
>> +};
>> +
>> +static int __init vimc_init(void)
>> +{
>> +	int ret;
>> +
>> +	ret = platform_device_register(&vimc_pdev);
>
> You could declare vimc_pdev closer to this.
>
>> +	if (ret) {
>> +		dev_err(&vimc_pdev.dev,
>> +			"platform device registration failed (err=%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = platform_driver_register(&vimc_pdrv);
>> +	if (ret) {
>> +		dev_err(&vimc_pdev.dev,
>> +			"platform driver registration failed (err=%d)\n", ret);
>> +
>> +		platform_device_unregister(&vimc_pdev);
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static void __exit vimc_exit(void)
>> +{
>> +	platform_driver_unregister(&vimc_pdrv);
>> +
>> +	platform_device_unregister(&vimc_pdev);
>> +}
>> +
>> +module_init(vimc_init);
>> +module_exit(vimc_exit);
>> +
>> +MODULE_DESCRIPTION("Virtual Media Controller Driver (VIMC)");
>> +MODULE_AUTHOR("Helen Fornazier <helen.fornazier@gmail.com>");
>> +MODULE_LICENSE("GPL");
>> diff --git a/drivers/media/platform/vimc/vimc-core.h b/drivers/media/platform/vimc/vimc-core.h
>> new file mode 100644
>> index 0000000..bd7abff
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-core.h
>> @@ -0,0 +1,57 @@
>> +/*
>> + * vimc-core.h Virtual Media Controller Driver
>> + *
>> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#ifndef _VIMC_CORE_H_
>> +#define _VIMC_CORE_H_
>> +
>> +#include <linux/slab.h>
>> +#include <media/v4l2-device.h>
>> +
>> +/* Struct which matches the MEDIA_BUS_FMT_ codes with the corresponding
>
> /*
>
>> + * V4L2_PIX_FMT_ fourcc pixelformat and its bytes per pixel (bpp)
>> + */
>> +struct vimc_pix_map {
>> +	unsigned int code;
>> +	unsigned int bpp;
>> +	u32 pixelformat;
>> +};
>> +extern const struct vimc_pix_map vimc_pix_map_list[];
>> +
>> +struct vimc_ent_device {
>> +	struct media_entity *ent;
>> +	struct media_pad *pads;
>> +	void (*destroy)(struct vimc_ent_device *);
>> +	void (*process_frame)(struct vimc_ent_device *ved,
>> +			      struct media_pad *sink, const void *frame);
>> +};
>> +
>> +int vimc_propagate_frame(struct device *dev,
>> +			 struct media_pad *src, const void *frame);
>> +
>> +/* Helper functions to allocate/initialize pads and free them */
>> +struct media_pad *vimc_pads_init(u16 num_pads,
>> +				 const unsigned long *pads_flag);
>> +static inline void vimc_pads_cleanup(struct media_pad *pads)
>> +{
>> +	kfree(pads);
>> +}
>> +
>> +const struct vimc_pix_map *vimc_pix_map_by_code(u32 code);
>> +
>> +const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat);
>> +
>> +#endif
>> diff --git a/drivers/media/platform/vimc/vimc-sensor.c b/drivers/media/platform/vimc/vimc-sensor.c
>> new file mode 100644
>> index 0000000..174e5dc
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-sensor.c
>> @@ -0,0 +1,279 @@
>> +/*
>> + * vimc-sensor.c Virtual Media Controller Driver
>> + *
>> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#include <linux/freezer.h>
>> +#include <linux/kthread.h>
>> +#include <linux/vmalloc.h>
>> +#include <linux/v4l2-mediabus.h>
>> +#include <media/v4l2-subdev.h>
>
> Alphabetic order, please.
>
>> +
>> +#include "vimc-sensor.h"
>> +
>> +struct vimc_sen_device {
>> +	struct vimc_ent_device ved;
>> +	struct v4l2_subdev sd;
>> +	struct v4l2_device *v4l2_dev;
>> +	struct device *dev;
>> +	struct task_struct *kthread_sen;
>> +	u8 *frame;
>> +	/* The active format */
>> +	struct v4l2_mbus_framefmt mbus_format;
>> +	int frame_size;
>> +};
>> +
>> +static int vimc_sen_enum_mbus_code(struct v4l2_subdev *sd,
>> +				   struct v4l2_subdev_pad_config *cfg,
>> +				   struct v4l2_subdev_mbus_code_enum *code)
>> +{
>> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
>> +
>> +	/* Check if it is a valid pad */
>> +	if (code->pad >= vsen->sd.entity.num_pads)
>> +		return -EINVAL;
>
> The check is already performed in v4l2-subdev.c.
>
>> +
>> +	code->code = vsen->mbus_format.code;
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_sen_enum_frame_size(struct v4l2_subdev *sd,
>> +				    struct v4l2_subdev_pad_config *cfg,
>> +				    struct v4l2_subdev_frame_size_enum *fse)
>> +{
>> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
>> +
>> +	/* Check if it is a valid pad */
>> +	if (fse->pad >= vsen->sd.entity.num_pads)
>> +		return -EINVAL;
>
> Same here.
>
>> +
>> +	/* TODO: Add support to other formats */
>> +	if (fse->index)
>> +		return -EINVAL;
>> +
>> +	/* TODO: Add support for other codes */
>> +	if (fse->code != vsen->mbus_format.code)
>> +		return -EINVAL;
>> +
>> +	fse->min_width = vsen->mbus_format.width;
>> +	fse->max_width = vsen->mbus_format.width;
>> +	fse->min_height = vsen->mbus_format.height;
>> +	fse->max_height = vsen->mbus_format.height;
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_sen_get_fmt(struct v4l2_subdev *sd,
>> +			    struct v4l2_subdev_pad_config *cfg,
>> +			    struct v4l2_subdev_format *format)
>> +{
>> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
>> +
>> +	format->format = vsen->mbus_format;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct v4l2_subdev_pad_ops vimc_sen_pad_ops = {
>> +	.enum_mbus_code		= vimc_sen_enum_mbus_code,
>> +	.enum_frame_size	= vimc_sen_enum_frame_size,
>> +	.get_fmt		= vimc_sen_get_fmt,
>> +	/* TODO: Add support to other formats */
>> +	.set_fmt		= vimc_sen_get_fmt,
>> +};
>> +
>> +/* media operations */
>> +static const struct media_entity_operations vimc_sen_mops = {
>> +	.link_validate = v4l2_subdev_link_validate,
>> +};
>> +
>> +static int vimc_thread_sen(void *data)
>> +{
>> +	unsigned int i;
>> +	struct vimc_sen_device *vsen = data;
>> +
>> +	set_freezable();
>> +
>> +	for (;;) {
>> +		try_to_freeze();
>> +		if (kthread_should_stop())
>> +			break;
>> +
>> +		memset(vsen->frame, 100, vsen->frame_size);
>> +
>> +		/* Send the frame to all source pads */
>> +		for (i = 0; i < vsen->sd.entity.num_pads; i++)
>> +			vimc_propagate_frame(vsen->dev,
>> +					     &vsen->sd.entity.pads[i],
>> +					     vsen->frame);
>> +
>> +		/* 60 frames per second */
>> +		schedule_timeout_interruptible(HZ/60);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
>> +{
>> +	int ret;
>> +	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
>> +
>> +	if (enable) {
>> +		const struct vimc_pix_map *vpix;
>> +
>> +		if (vsen->kthread_sen)
>> +			return -EINVAL;
>> +
>> +		/* Calculate the frame size */
>> +		vpix = vimc_pix_map_by_code(vsen->mbus_format.code);
>> +		vsen->frame_size = vsen->mbus_format.width * vpix->bpp *
>> +				   vsen->mbus_format.height;
>> +
>> +		/* Allocate the frame buffer. Use vmalloc to be able to
>
> /*
>  *
>
>> +		 * allocate a large amount of memory
>> +		 */
>> +		vsen->frame = vmalloc(vsen->frame_size);
>> +		if (!vsen->frame)
>> +			return -ENOMEM;
>> +
>> +		/* Initialize the image generator thread */
>> +		vsen->kthread_sen = kthread_run(vimc_thread_sen, vsen,
>> +						"%s-sen", vsen->v4l2_dev->name);
>
> We have no other kthreads, just the video device name should be enough.
>
>> +		if (IS_ERR(vsen->kthread_sen)) {
>> +			v4l2_err(vsen->v4l2_dev, "kernel_thread() failed\n");
>
> How about dev_err() instead? You use dev_*() macros elsewhere for printing.
>
>> +			vfree(vsen->frame);
>> +			vsen->frame = NULL;
>> +			return PTR_ERR(vsen->kthread_sen);
>> +		}
>> +	} else {
>> +		if (!vsen->kthread_sen)
>> +			return -EINVAL;
>> +
>> +		/* Stop image generator */
>> +		ret = kthread_stop(vsen->kthread_sen);
>> +		vsen->kthread_sen = NULL;
>> +
>> +		vfree(vsen->frame);
>> +		vsen->frame = NULL;
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +struct v4l2_subdev_video_ops vimc_sen_video_ops = {
>> +	.s_stream = vimc_sen_s_stream,
>> +};
>> +
>> +static const struct v4l2_subdev_ops vimc_sen_ops = {
>> +	.pad = &vimc_sen_pad_ops,
>> +	.video = &vimc_sen_video_ops,
>> +};
>> +
>> +static void vimc_sen_destroy(struct vimc_ent_device *ved)
>> +{
>> +	struct vimc_sen_device *vsen = container_of(ved,
>> +						struct vimc_sen_device, ved);
>> +
>> +	media_entity_cleanup(ved->ent);
>> +	v4l2_device_unregister_subdev(&vsen->sd);
>
> I'd say media_entity_cleanup() would belong here but it's an empty function
> nowadays...
>
>> +	kfree(vsen);
>> +}
>> +
>> +struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
>> +					const char *const name,
>> +					u16 num_pads,
>> +					const unsigned long *pads_flag)
>> +{
>> +	int ret;
>> +	unsigned int i;
>> +	struct vimc_sen_device *vsen;
>
> vsen first?
>
>> +
>> +	if (!name || (num_pads && !pads_flag))
>> +		return ERR_PTR(-EINVAL);
>> +	/* check if all pads are sources */
>> +	for (i = 0; i < num_pads; i++)
>> +		if (!(pads_flag[i] & MEDIA_PAD_FL_SOURCE))
>> +			return ERR_PTR(-EINVAL);
>> +
>> +	/* Allocate the vsen struct */
>> +	vsen = kzalloc(sizeof(*vsen), GFP_KERNEL);
>> +	if (!vsen)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	/* Link the vimc_sen_device struct with the v4l2 parent */
>> +	vsen->v4l2_dev = v4l2_dev;
>> +	/* Link the vimc_sen_device struct with the dev parent */
>> +	vsen->dev = v4l2_dev->dev;
>> +
>> +	/* Allocate the pads */
>> +	vsen->ved.pads = vimc_pads_init(num_pads, pads_flag);
>> +	if (IS_ERR(vsen->ved.pads)) {
>> +		ret = PTR_ERR(vsen->ved.pads);
>> +		goto err_free_vsen;
>> +	}
>> +
>> +	/* Initialize the media entity */
>> +	vsen->sd.entity.name = name;
>> +	ret = media_entity_pads_init(&vsen->sd.entity,
>> +				     num_pads, vsen->ved.pads);
>> +	if (ret)
>> +		goto err_clean_pads;
>> +
>> +	/* Set the active frame format (this is hardcoded for now) */
>> +	vsen->mbus_format.width = 640;
>> +	vsen->mbus_format.height = 480;
>> +	vsen->mbus_format.code = MEDIA_BUS_FMT_RGB888_1X24;
>> +	vsen->mbus_format.field = V4L2_FIELD_NONE;
>> +	vsen->mbus_format.colorspace = V4L2_COLORSPACE_SRGB;
>> +	vsen->mbus_format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
>> +	vsen->mbus_format.xfer_func = V4L2_XFER_FUNC_SRGB;
>> +
>> +	/* Fill the vimc_ent_device struct */
>> +	vsen->ved.destroy = vimc_sen_destroy;
>> +	vsen->ved.ent = &vsen->sd.entity;
>> +
>> +	/* Initialize the subdev */
>> +	v4l2_subdev_init(&vsen->sd, &vimc_sen_ops);
>> +	vsen->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
>> +	vsen->sd.entity.ops = &vimc_sen_mops;
>> +	vsen->sd.owner = THIS_MODULE;
>> +	strlcpy(vsen->sd.name, name, sizeof(vsen->sd.name));
>> +	v4l2_set_subdevdata(&vsen->sd, vsen);
>> +
>> +	/* Expose this subdev to user space */
>> +	vsen->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
>> +
>> +	/* Register the subdev with the v4l2 and the media framework */
>> +	ret = v4l2_device_register_subdev(vsen->v4l2_dev, &vsen->sd);
>> +	if (ret) {
>> +		dev_err(vsen->dev,
>> +			"subdev register failed (err=%d)\n", ret);
>> +		goto err_clean_m_ent;
>> +	}
>> +
>> +	return &vsen->ved;
>> +
>> +err_clean_m_ent:
>> +	media_entity_cleanup(&vsen->sd.entity);
>> +err_clean_pads:
>> +	vimc_pads_cleanup(vsen->ved.pads);
>> +err_free_vsen:
>> +	kfree(vsen);
>> +
>> +	return ERR_PTR(ret);
>> +}
>> diff --git a/drivers/media/platform/vimc/vimc-sensor.h b/drivers/media/platform/vimc/vimc-sensor.h
>> new file mode 100644
>> index 0000000..ffeaf6c
>> --- /dev/null
>> +++ b/drivers/media/platform/vimc/vimc-sensor.h
>> @@ -0,0 +1,28 @@
>> +/*
>> + * vimc-sensor.h Virtual Media Controller Driver
>> + *
>> + * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#ifndef _VIMC_SENSOR_H_
>> +#define _VIMC_SENSOR_H_
>> +
>> +#include "vimc-core.h"
>> +
>> +struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
>> +					const char *const name,
>> +					u16 num_pads,
>> +					const unsigned long *pads_flag);
>> +
>> +#endif
>
> Looks very nice in general! I'll try this out soon.
>

Helen Koike
Sakari Ailus March 26, 2017, 1:25 p.m. UTC | #9
Hi Helen,

Please see my comments below.

Helen Koike wrote:
> On 2017-01-25 11:03 AM, Sakari Ailus wrote:
...
>>> +     * the videobuf2 framework will allocate this struct based on
>>> +     * buf_struct_size and use the first sizeof(struct vb2_buffer)
>>> bytes of
>>> +     * memory as a vb2_buffer
>>> +     */
>>> +    struct vb2_v4l2_buffer vb2;
>>> +    struct list_head list;
>>> +};
>>> +
>>> +static int vimc_cap_querycap(struct file *file, void *priv,
>>> +                 struct v4l2_capability *cap)
>>> +{
>>> +    struct vimc_cap_device *vcap = video_drvdata(file);
>>> +
>>> +    strlcpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
>>> +    strlcpy(cap->card, KBUILD_MODNAME, sizeof(cap->card));
>>> +    snprintf(cap->bus_info, sizeof(cap->bus_info),
>>> +         "platform:%s", vcap->v4l2_dev->name);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int vimc_cap_enum_input(struct file *file, void *priv,
>>> +                   struct v4l2_input *i)
>>> +{
>>> +    /* We only have one input */
>>> +    if (i->index > 0)
>>> +        return -EINVAL;
>>> +
>>> +    i->type = V4L2_INPUT_TYPE_CAMERA;
>>> +    strlcpy(i->name, "VIMC capture", sizeof(i->name));
>>
>> Isn't this (*INPUT IOCTLs) something that should be handled in a
>> sub-device
>> driver, such as a TV tuner?
> 
> 
> Can the ioctl VIDIOC_ENUMINPUT enumerate no inputs at all? Can I just
> return -EINVAL here in G_INPUT and S_INPUT as well?
> I thought I had to enumerate at least one input, and between
> V4L2_INPUT_TYPE_TUNER and V4L2_INPUT_TYPE_CAMERA, this last
> one seems more appropriated

I don't think other drivers that provide MC interface do this on video
nodes either. The VIMC driver could know what's connected to it, but
generally that's not the case.

> 
> 
>>
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int vimc_cap_g_input(struct file *file, void *priv, unsigned
>>> int *i)
>>> +{
>>> +    /* We only have one input */
>>> +    *i = 0;
>>> +    return 0;
>>> +}
>>> +
>>> +static int vimc_cap_s_input(struct file *file, void *priv, unsigned
>>> int i)
>>> +{
>>> +    /* We only have one input */
>>> +    return i ? -EINVAL : 0;
>>> +}
>>> +
>>> +static int vimc_cap_fmt_vid_cap(struct file *file, void *priv,
>>> +                  struct v4l2_format *f)
>>> +{
>>> +    struct vimc_cap_device *vcap = video_drvdata(file);
>>> +
>>> +    f->fmt.pix = vcap->format;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int vimc_cap_enum_fmt_vid_cap(struct file *file, void *priv,
>>> +                     struct v4l2_fmtdesc *f)
>>> +{
>>> +    struct vimc_cap_device *vcap = video_drvdata(file);
>>> +
>>> +    if (f->index > 0)
>>> +        return -EINVAL;
>>> +
>>> +    /* We only support one format for now */
>>> +    f->pixelformat = vcap->format.pixelformat;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static const struct v4l2_file_operations vimc_cap_fops = {
>>> +    .owner        = THIS_MODULE,
>>> +    .open        = v4l2_fh_open,
>>> +    .release    = vb2_fop_release,
>>> +    .read           = vb2_fop_read,
>>> +    .poll        = vb2_fop_poll,
>>> +    .unlocked_ioctl = video_ioctl2,
>>> +    .mmap           = vb2_fop_mmap,
>>> +};
>>> +
>>> +static const struct v4l2_ioctl_ops vimc_cap_ioctl_ops = {
>>> +    .vidioc_querycap = vimc_cap_querycap,
>>> +
>>> +    .vidioc_enum_input = vimc_cap_enum_input,
>>> +    .vidioc_g_input = vimc_cap_g_input,
>>> +    .vidioc_s_input = vimc_cap_s_input,
>>> +
>>> +    .vidioc_g_fmt_vid_cap = vimc_cap_fmt_vid_cap,
>>> +    .vidioc_s_fmt_vid_cap = vimc_cap_fmt_vid_cap,
>>> +    .vidioc_try_fmt_vid_cap = vimc_cap_fmt_vid_cap,
>>> +    .vidioc_enum_fmt_vid_cap = vimc_cap_enum_fmt_vid_cap,
>>> +
>>> +    .vidioc_reqbufs = vb2_ioctl_reqbufs,
>>> +    .vidioc_create_bufs = vb2_ioctl_create_bufs,
>>> +    .vidioc_querybuf = vb2_ioctl_querybuf,
>>> +    .vidioc_qbuf = vb2_ioctl_qbuf,
>>> +    .vidioc_dqbuf = vb2_ioctl_dqbuf,
>>> +    .vidioc_expbuf = vb2_ioctl_expbuf,
>>> +    .vidioc_streamon = vb2_ioctl_streamon,
>>> +    .vidioc_streamoff = vb2_ioctl_streamoff,
>>> +};
>>> +
>>> +static void vimc_cap_return_all_buffers(struct vimc_cap_device *vcap,
>>> +                    enum vb2_buffer_state state)
>>> +{
>>> +    struct vimc_cap_buffer *vbuf, *node;
>>> +
>>> +    spin_lock(&vcap->qlock);
>>> +
>>> +    list_for_each_entry_safe(vbuf, node, &vcap->buf_list, list) {
>>> +        vb2_buffer_done(&vbuf->vb2.vb2_buf, state);
>>> +        list_del(&vbuf->list);
>>> +    }
>>> +
>>> +    spin_unlock(&vcap->qlock);
>>> +}
>>> +
>>> +static int vimc_cap_pipeline_s_stream(struct vimc_cap_device *vcap,
>>> int enable)
>>> +{
>>> +    int ret;
>>> +    struct media_pad *pad;
>>> +    struct media_entity *entity;
>>> +    struct v4l2_subdev *sd;
>>> +
>>> +    /* Start the stream in the subdevice direct connected */
>>> +    entity = &vcap->vdev.entity;
>>> +    pad = media_entity_remote_pad(&entity->pads[0]);
>>
>> You could use vcap->vdev.entity.pads here, without assigning to
>> entity. Then
>> entity would only be used to refer to the remove entity at the other
>> end of
>> the link. Up to you.
>>
>>> +
>>> +    /* If we are not connected to any subdev node, it means there is
>>> nothing
>>
>> /*
>>  * Multi line
>>  * comment.
>>  */
>>
>>> +     * to activate on the pipe (e.g. we can be connected with an input
>>> +     * device or we are not connected at all)
>>> +     */
>>> +    if (pad == NULL || !is_media_entity_v4l2_subdev(pad->entity))
>>> +        return 0;
>>> +
>>> +    entity = pad->entity;
>>> +    sd = media_entity_to_v4l2_subdev(entity);
>>
>> And if you used pad->entity here, you could remove the entity variable
>> altogether.
>>
>>> +
>>> +    ret = v4l2_subdev_call(sd, video, s_stream, enable);
>>> +    if (ret && ret != -ENOIOCTLCMD)
>>> +        return ret;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned
>>> int count)
>>> +{
>>> +    struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>>> +    struct media_entity *entity;
>>> +    int ret;
>>> +
>>> +    vcap->sequence = 0;
>>> +
>>> +    /* Start the media pipeline */
>>> +    entity = &vcap->vdev.entity;
>>> +    ret = media_entity_pipeline_start(entity, &vcap->pipe);
>>> +    if (ret) {
>>> +        vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
>>> +        return ret;
>>> +    }
>>> +
>>> +    /* Enable streaming from the pipe */
>>> +    ret = vimc_cap_pipeline_s_stream(vcap, 1);
>>> +    if (ret) {
>>> +        vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
>>> +        return ret;
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +/*
>>> + * Stop the stream engine. Any remaining buffers in the stream queue
>>> are
>>> + * dequeued and passed on to the vb2 framework marked as STATE_ERROR.
>>> + */
>>> +static void vimc_cap_stop_streaming(struct vb2_queue *vq)
>>> +{
>>> +    struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>>> +
>>> +    /* Disable streaming from the pipe */
>>> +    vimc_cap_pipeline_s_stream(vcap, 0);
>>> +
>>> +    /* Stop the media pipeline */
>>> +    media_entity_pipeline_stop(&vcap->vdev.entity);
>>> +
>>> +    /* Release all active buffers */
>>> +    vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_ERROR);
>>> +}
>>> +
>>> +static void vimc_cap_buf_queue(struct vb2_buffer *vb2_buf)
>>> +{
>>> +    struct vimc_cap_device *vcap =
>>> vb2_get_drv_priv(vb2_buf->vb2_queue);
>>> +    struct vimc_cap_buffer *buf = container_of(vb2_buf,
>>> +                           struct vimc_cap_buffer,
>>> +                           vb2.vb2_buf);
>>> +
>>> +    spin_lock(&vcap->qlock);
>>> +    list_add_tail(&buf->list, &vcap->buf_list);
>>> +    spin_unlock(&vcap->qlock);
>>> +}
>>> +
>>> +static int vimc_cap_queue_setup(struct vb2_queue *vq, unsigned int
>>> *nbuffers,
>>> +                unsigned int *nplanes, unsigned int sizes[],
>>> +                struct device *alloc_devs[])
>>> +{
>>> +    struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
>>> +
>>> +    if (*nplanes)
>>> +        return sizes[0] < vcap->format.sizeimage ? -EINVAL : 0;
>>
>> Why? The user could later reconfigure the device to use with a buffer of
>> this size. This might not be a concern for vimc, but the code from
>> example
>> drivers tends to get copied around.
> 
> 
> This first version only support a fixed sizeimage, this will be changed
> in the next patch series where
> I add support for multiple sizes

Sounds good to me. Thanks.
diff mbox

Patch

diff --git a/drivers/media/platform/Kconfig b/drivers/media/platform/Kconfig
index 46f14dd..4a0577f 100644
--- a/drivers/media/platform/Kconfig
+++ b/drivers/media/platform/Kconfig
@@ -329,6 +329,8 @@  menuconfig V4L_TEST_DRIVERS
 
 if V4L_TEST_DRIVERS
 
+source "drivers/media/platform/vimc/Kconfig"
+
 source "drivers/media/platform/vivid/Kconfig"
 
 config VIDEO_VIM2M
diff --git a/drivers/media/platform/Makefile b/drivers/media/platform/Makefile
index 536d1d8..dd4f658 100644
--- a/drivers/media/platform/Makefile
+++ b/drivers/media/platform/Makefile
@@ -12,6 +12,7 @@  obj-$(CONFIG_VIDEO_OMAP3)	+= omap3isp/
 
 obj-$(CONFIG_VIDEO_VIU) += fsl-viu.o
 
+obj-$(CONFIG_VIDEO_VIMC)		+= vimc/
 obj-$(CONFIG_VIDEO_VIVID)		+= vivid/
 obj-$(CONFIG_VIDEO_VIM2M)		+= vim2m.o
 
diff --git a/drivers/media/platform/vimc/Kconfig b/drivers/media/platform/vimc/Kconfig
new file mode 100644
index 0000000..b48819c
--- /dev/null
+++ b/drivers/media/platform/vimc/Kconfig
@@ -0,0 +1,7 @@ 
+config VIDEO_VIMC
+	tristate "Virtual Media Controller Driver (VIMC)"
+	depends on VIDEO_DEV && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
+	select VIDEOBUF2_VMALLOC
+	default n
+	---help---
+	  Skeleton driver for Virtual Media Controller
diff --git a/drivers/media/platform/vimc/Makefile b/drivers/media/platform/vimc/Makefile
new file mode 100644
index 0000000..c45195e
--- /dev/null
+++ b/drivers/media/platform/vimc/Makefile
@@ -0,0 +1,3 @@ 
+vimc-objs := vimc-core.o vimc-capture.o vimc-sensor.o
+
+obj-$(CONFIG_VIDEO_VIMC) += vimc.o
diff --git a/drivers/media/platform/vimc/vimc-capture.c b/drivers/media/platform/vimc/vimc-capture.c
new file mode 100644
index 0000000..b7636cf
--- /dev/null
+++ b/drivers/media/platform/vimc/vimc-capture.c
@@ -0,0 +1,553 @@ 
+/*
+ * vimc-capture.c Virtual Media Controller Driver
+ *
+ * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <media/videobuf2-core.h>
+#include <media/videobuf2-vmalloc.h>
+#include <media/v4l2-ioctl.h>
+
+#include "vimc-capture.h"
+
+struct vimc_cap_device {
+	struct vimc_ent_device ved;
+	struct video_device vdev;
+	struct v4l2_device *v4l2_dev;
+	struct device *dev;
+	struct v4l2_pix_format format;
+	struct vb2_queue queue;
+	struct list_head buf_list;
+	/*
+	 * NOTE: in a real driver, a spin lock must be used to access the
+	 * queue because the frames are generated from a hardware interruption
+	 * and the isr is not allowed to sleep.
+	 * Even if it is not necessary a spinlock in the vimc driver, we
+	 * use it here as a code reference
+	 */
+	spinlock_t qlock;
+	struct mutex lock;
+	u32 sequence;
+	struct media_pipeline pipe;
+};
+
+struct vimc_cap_buffer {
+	/*
+	 * vb2_buffer must be the first element
+	 * the videobuf2 framework will allocate this struct based on
+	 * buf_struct_size and use the first sizeof(struct vb2_buffer) bytes of
+	 * memory as a vb2_buffer
+	 */
+	struct vb2_v4l2_buffer vb2;
+	struct list_head list;
+};
+
+static int vimc_cap_querycap(struct file *file, void *priv,
+			     struct v4l2_capability *cap)
+{
+	struct vimc_cap_device *vcap = video_drvdata(file);
+
+	strlcpy(cap->driver, KBUILD_MODNAME, sizeof(cap->driver));
+	strlcpy(cap->card, KBUILD_MODNAME, sizeof(cap->card));
+	snprintf(cap->bus_info, sizeof(cap->bus_info),
+		 "platform:%s", vcap->v4l2_dev->name);
+
+	return 0;
+}
+
+static int vimc_cap_enum_input(struct file *file, void *priv,
+			       struct v4l2_input *i)
+{
+	/* We only have one input */
+	if (i->index > 0)
+		return -EINVAL;
+
+	i->type = V4L2_INPUT_TYPE_CAMERA;
+	strlcpy(i->name, "VIMC capture", sizeof(i->name));
+
+	return 0;
+}
+
+static int vimc_cap_g_input(struct file *file, void *priv, unsigned int *i)
+{
+	/* We only have one input */
+	*i = 0;
+	return 0;
+}
+
+static int vimc_cap_s_input(struct file *file, void *priv, unsigned int i)
+{
+	/* We only have one input */
+	return i ? -EINVAL : 0;
+}
+
+static int vimc_cap_fmt_vid_cap(struct file *file, void *priv,
+				  struct v4l2_format *f)
+{
+	struct vimc_cap_device *vcap = video_drvdata(file);
+
+	f->fmt.pix = vcap->format;
+
+	return 0;
+}
+
+static int vimc_cap_enum_fmt_vid_cap(struct file *file, void *priv,
+				     struct v4l2_fmtdesc *f)
+{
+	struct vimc_cap_device *vcap = video_drvdata(file);
+
+	if (f->index > 0)
+		return -EINVAL;
+
+	/* We only support one format for now */
+	f->pixelformat = vcap->format.pixelformat;
+
+	return 0;
+}
+
+static const struct v4l2_file_operations vimc_cap_fops = {
+	.owner		= THIS_MODULE,
+	.open		= v4l2_fh_open,
+	.release	= vb2_fop_release,
+	.read           = vb2_fop_read,
+	.poll		= vb2_fop_poll,
+	.unlocked_ioctl = video_ioctl2,
+	.mmap           = vb2_fop_mmap,
+};
+
+static const struct v4l2_ioctl_ops vimc_cap_ioctl_ops = {
+	.vidioc_querycap = vimc_cap_querycap,
+
+	.vidioc_enum_input = vimc_cap_enum_input,
+	.vidioc_g_input = vimc_cap_g_input,
+	.vidioc_s_input = vimc_cap_s_input,
+
+	.vidioc_g_fmt_vid_cap = vimc_cap_fmt_vid_cap,
+	.vidioc_s_fmt_vid_cap = vimc_cap_fmt_vid_cap,
+	.vidioc_try_fmt_vid_cap = vimc_cap_fmt_vid_cap,
+	.vidioc_enum_fmt_vid_cap = vimc_cap_enum_fmt_vid_cap,
+
+	.vidioc_reqbufs = vb2_ioctl_reqbufs,
+	.vidioc_create_bufs = vb2_ioctl_create_bufs,
+	.vidioc_querybuf = vb2_ioctl_querybuf,
+	.vidioc_qbuf = vb2_ioctl_qbuf,
+	.vidioc_dqbuf = vb2_ioctl_dqbuf,
+	.vidioc_expbuf = vb2_ioctl_expbuf,
+	.vidioc_streamon = vb2_ioctl_streamon,
+	.vidioc_streamoff = vb2_ioctl_streamoff,
+};
+
+static void vimc_cap_return_all_buffers(struct vimc_cap_device *vcap,
+					enum vb2_buffer_state state)
+{
+	struct vimc_cap_buffer *vbuf, *node;
+
+	spin_lock(&vcap->qlock);
+
+	list_for_each_entry_safe(vbuf, node, &vcap->buf_list, list) {
+		vb2_buffer_done(&vbuf->vb2.vb2_buf, state);
+		list_del(&vbuf->list);
+	}
+
+	spin_unlock(&vcap->qlock);
+}
+
+static int vimc_cap_pipeline_s_stream(struct vimc_cap_device *vcap, int enable)
+{
+	int ret;
+	struct media_pad *pad;
+	struct media_entity *entity;
+	struct v4l2_subdev *sd;
+
+	/* Start the stream in the subdevice direct connected */
+	entity = &vcap->vdev.entity;
+	pad = media_entity_remote_pad(&entity->pads[0]);
+
+	/* If we are not connected to any subdev node, it means there is nothing
+	 * to activate on the pipe (e.g. we can be connected with an input
+	 * device or we are not connected at all)
+	 */
+	if (pad == NULL || !is_media_entity_v4l2_subdev(pad->entity))
+		return 0;
+
+	entity = pad->entity;
+	sd = media_entity_to_v4l2_subdev(entity);
+
+	ret = v4l2_subdev_call(sd, video, s_stream, enable);
+	if (ret && ret != -ENOIOCTLCMD)
+		return ret;
+
+	return 0;
+}
+
+static int vimc_cap_start_streaming(struct vb2_queue *vq, unsigned int count)
+{
+	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
+	struct media_entity *entity;
+	int ret;
+
+	vcap->sequence = 0;
+
+	/* Start the media pipeline */
+	entity = &vcap->vdev.entity;
+	ret = media_entity_pipeline_start(entity, &vcap->pipe);
+	if (ret) {
+		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
+		return ret;
+	}
+
+	/* Enable streaming from the pipe */
+	ret = vimc_cap_pipeline_s_stream(vcap, 1);
+	if (ret) {
+		vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_QUEUED);
+		return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * Stop the stream engine. Any remaining buffers in the stream queue are
+ * dequeued and passed on to the vb2 framework marked as STATE_ERROR.
+ */
+static void vimc_cap_stop_streaming(struct vb2_queue *vq)
+{
+	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
+
+	/* Disable streaming from the pipe */
+	vimc_cap_pipeline_s_stream(vcap, 0);
+
+	/* Stop the media pipeline */
+	media_entity_pipeline_stop(&vcap->vdev.entity);
+
+	/* Release all active buffers */
+	vimc_cap_return_all_buffers(vcap, VB2_BUF_STATE_ERROR);
+}
+
+static void vimc_cap_buf_queue(struct vb2_buffer *vb2_buf)
+{
+	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb2_buf->vb2_queue);
+	struct vimc_cap_buffer *buf = container_of(vb2_buf,
+						   struct vimc_cap_buffer,
+						   vb2.vb2_buf);
+
+	spin_lock(&vcap->qlock);
+	list_add_tail(&buf->list, &vcap->buf_list);
+	spin_unlock(&vcap->qlock);
+}
+
+static int vimc_cap_queue_setup(struct vb2_queue *vq, unsigned int *nbuffers,
+				unsigned int *nplanes, unsigned int sizes[],
+				struct device *alloc_devs[])
+{
+	struct vimc_cap_device *vcap = vb2_get_drv_priv(vq);
+
+	if (*nplanes)
+		return sizes[0] < vcap->format.sizeimage ? -EINVAL : 0;
+	/* We don't support multiplanes for now */
+	*nplanes = 1;
+	sizes[0] = vcap->format.sizeimage;
+
+	return 0;
+}
+
+/*
+ * Prepare the buffer for queueing to the DMA engine: check and set the
+ * payload size.
+ */
+static int vimc_cap_buffer_prepare(struct vb2_buffer *vb)
+{
+	struct vimc_cap_device *vcap = vb2_get_drv_priv(vb->vb2_queue);
+	unsigned long size = vcap->format.sizeimage;
+
+	if (vb2_plane_size(vb, 0) < size) {
+		dev_err(vcap->dev, "buffer too small (%lu < %lu)\n",
+			vb2_plane_size(vb, 0), size);
+		return -EINVAL;
+	}
+
+	vb2_set_plane_payload(vb, 0, size);
+	return 0;
+}
+
+static const struct vb2_ops vimc_cap_qops = {
+	.start_streaming	= vimc_cap_start_streaming,
+	.stop_streaming		= vimc_cap_stop_streaming,
+	.buf_queue		= vimc_cap_buf_queue,
+	.queue_setup		= vimc_cap_queue_setup,
+	.buf_prepare		= vimc_cap_buffer_prepare,
+	/*
+	 * Since q->lock is set we can use the standard
+	 * vb2_ops_wait_prepare/finish helper functions.
+	 */
+	.wait_prepare		= vb2_ops_wait_prepare,
+	.wait_finish		= vb2_ops_wait_finish,
+};
+
+/* NOTE: this function is a copy of v4l2_subdev_link_validate_get_format
+ * maybe the v4l2 function should be public
+ */
+static int vimc_cap_v4l2_subdev_link_validate_get_format(struct media_pad *pad,
+						struct v4l2_subdev_format *fmt)
+{
+	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(pad->entity);
+
+	fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
+	fmt->pad = pad->index;
+	return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);
+}
+
+static int vimc_cap_link_validate(struct media_link *link)
+{
+	struct v4l2_subdev_format source_fmt;
+	struct v4l2_pix_format *sink_fmt;
+	struct vimc_cap_device *vcap;
+	const struct vimc_pix_map *vpix;
+	int ret;
+
+	/* Retrieve the video capture device */
+	vcap = container_of(link->sink->entity,
+			    struct vimc_cap_device, vdev.entity);
+
+	/* If the connected node is not a subdevice type
+	 * then it's a raw node from vimc-core, ignore the link for now
+	 * TODO: remove this when there are no more raw nodes in the
+	 * core and return error instead
+	 */
+	if (!is_media_entity_v4l2_subdev(link->source->entity))
+		return 0;
+
+	/* Get the the format of the video device */
+	sink_fmt = &vcap->format;
+
+	/* Get the the format of the subdev */
+	ret = vimc_cap_v4l2_subdev_link_validate_get_format(link->source,
+							    &source_fmt);
+	if (ret)
+		return ret;
+
+	dev_dbg(vcap->dev,
+		"cap: %s: link validate formats src:%dx%d %d sink:%dx%d %d\n",
+		vcap->vdev.name,
+		source_fmt.format.width, source_fmt.format.height,
+		source_fmt.format.code,
+		sink_fmt->width, sink_fmt->height,
+		sink_fmt->pixelformat);
+
+	/* Validate the format */
+
+	vpix = vimc_pix_map_by_pixelformat(sink_fmt->pixelformat);
+	if (!vpix)
+		return -EINVAL;
+
+	/* The width, height and code must match. */
+	if (source_fmt.format.width != sink_fmt->width
+	    || source_fmt.format.height != sink_fmt->height
+	    || vpix->code != source_fmt.format.code)
+		return -EINVAL;
+
+	/* The field order must match, or the sink field order must be NONE
+	 * to support interlaced hardware connected to bridges that support
+	 * progressive formats only.
+	 */
+	if (source_fmt.format.field != sink_fmt->field &&
+	    sink_fmt->field != V4L2_FIELD_NONE)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct media_entity_operations vimc_cap_mops = {
+	.link_validate		= vimc_cap_link_validate,
+};
+
+static void vimc_cap_destroy(struct vimc_ent_device *ved)
+{
+	struct vimc_cap_device *vcap = container_of(ved, struct vimc_cap_device,
+						    ved);
+
+	vb2_queue_release(&vcap->queue);
+	media_entity_cleanup(ved->ent);
+	video_unregister_device(&vcap->vdev);
+	vimc_pads_cleanup(vcap->ved.pads);
+	kfree(vcap);
+}
+
+static void vimc_cap_process_frame(struct vimc_ent_device *ved,
+				   struct media_pad *sink, const void *frame)
+{
+	struct vimc_cap_device *vcap = container_of(ved, struct vimc_cap_device,
+						    ved);
+	struct vimc_cap_buffer *vimc_buf;
+	void *vbuf;
+
+	/* If the stream in this node is not active, just return */
+	mutex_lock(&vcap->lock);
+	if (!vb2_is_busy(&vcap->queue)) {
+		mutex_unlock(&vcap->lock);
+		return;
+	}
+	mutex_unlock(&vcap->lock);
+
+	spin_lock(&vcap->qlock);
+
+	/* Get the first entry of the list */
+	vimc_buf = list_first_entry_or_null(&vcap->buf_list,
+					    typeof(*vimc_buf), list);
+	if (!vimc_buf) {
+		spin_unlock(&vcap->qlock);
+		return;
+	}
+
+	/* Remove this entry from the list */
+	list_del(&vimc_buf->list);
+
+	spin_unlock(&vcap->qlock);
+
+	/* Fill the buffer */
+	vimc_buf->vb2.vb2_buf.timestamp = ktime_get_ns();
+	vimc_buf->vb2.sequence = vcap->sequence++;
+	vimc_buf->vb2.field = vcap->format.field;
+
+	vbuf = vb2_plane_vaddr(&vimc_buf->vb2.vb2_buf, 0);
+
+	memcpy(vbuf, frame, vcap->format.sizeimage);
+
+	/* Set it as ready */
+	vb2_set_plane_payload(&vimc_buf->vb2.vb2_buf, 0,
+			      vcap->format.sizeimage);
+	vb2_buffer_done(&vimc_buf->vb2.vb2_buf, VB2_BUF_STATE_DONE);
+}
+
+struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
+					const char *const name,
+					u16 num_pads,
+					const unsigned long *pads_flag)
+{
+	int ret;
+	struct vb2_queue *q;
+	struct video_device *vdev;
+	struct vimc_cap_device *vcap;
+	const struct vimc_pix_map *vpix;
+
+	/* Check entity configuration params
+	 * NOTE: we only support a single sink pad
+	 */
+	if (!name || num_pads != 1 || !pads_flag ||
+	    !(pads_flag[0] & MEDIA_PAD_FL_SINK))
+		return ERR_PTR(-EINVAL);
+
+	/* Allocate the vimc_cap_device struct */
+	vcap = kzalloc(sizeof(*vcap), GFP_KERNEL);
+	if (!vcap)
+		return ERR_PTR(-ENOMEM);
+
+	/* Link the vimc_cap_device struct with v4l2 and dev parent */
+	vcap->v4l2_dev = v4l2_dev;
+	vcap->dev = v4l2_dev->dev;
+
+	/* Allocate the pads */
+	vcap->ved.pads = vimc_pads_init(num_pads, pads_flag);
+	if (IS_ERR(vcap->ved.pads)) {
+		ret = PTR_ERR(vcap->ved.pads);
+		goto err_free_vcap;
+	}
+
+	/* Initialize the media entity */
+	vcap->vdev.entity.name = name;
+	vcap->vdev.entity.function = MEDIA_ENT_F_IO_V4L;
+	ret = media_entity_pads_init(&vcap->vdev.entity,
+				     num_pads, vcap->ved.pads);
+	if (ret)
+		goto err_clean_pads;
+
+	/* Initialize the lock */
+	mutex_init(&vcap->lock);
+
+	/* Initialize the vb2 queue */
+	q = &vcap->queue;
+	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+	q->io_modes = VB2_MMAP | VB2_DMABUF;
+	q->drv_priv = vcap;
+	q->buf_struct_size = sizeof(struct vimc_cap_buffer);
+	q->ops = &vimc_cap_qops;
+	q->mem_ops = &vb2_vmalloc_memops;
+	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+	q->min_buffers_needed = 2;
+	q->lock = &vcap->lock;
+
+	ret = vb2_queue_init(q);
+	if (ret) {
+		dev_err(vcap->dev,
+			"vb2 queue init failed (err=%d)\n", ret);
+		goto err_clean_m_ent;
+	}
+
+	/* Initialize buffer list and its lock */
+	INIT_LIST_HEAD(&vcap->buf_list);
+	spin_lock_init(&vcap->qlock);
+
+	/* Set the frame format (this is hardcoded for now) */
+	vcap->format.width = 640;
+	vcap->format.height = 480;
+	vcap->format.pixelformat = V4L2_PIX_FMT_RGB24;
+	vcap->format.field = V4L2_FIELD_NONE;
+	vcap->format.colorspace = V4L2_COLORSPACE_SRGB;
+
+	vpix = vimc_pix_map_by_pixelformat(vcap->format.pixelformat);
+
+	vcap->format.bytesperline = vcap->format.width * vpix->bpp;
+	vcap->format.sizeimage = vcap->format.bytesperline *
+				 vcap->format.height;
+
+	/* Fill the vimc_ent_device struct */
+	vcap->ved.destroy = vimc_cap_destroy;
+	vcap->ved.ent = &vcap->vdev.entity;
+	vcap->ved.process_frame = vimc_cap_process_frame;
+
+	/* Initialize the video_device struct */
+	vdev = &vcap->vdev;
+	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
+	vdev->entity.ops = &vimc_cap_mops;
+	vdev->release = video_device_release_empty;
+	vdev->fops = &vimc_cap_fops;
+	vdev->ioctl_ops = &vimc_cap_ioctl_ops;
+	vdev->lock = &vcap->lock;
+	vdev->queue = q;
+	vdev->v4l2_dev = vcap->v4l2_dev;
+	vdev->vfl_dir = VFL_DIR_RX;
+	strlcpy(vdev->name, name, sizeof(vdev->name));
+	video_set_drvdata(vdev, vcap);
+
+	/* Register the video_device with the v4l2 and the media framework */
+	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
+	if (ret) {
+		dev_err(vcap->dev,
+			"video register failed (err=%d)\n", ret);
+		goto err_release_queue;
+	}
+
+	return &vcap->ved;
+
+err_release_queue:
+	vb2_queue_release(q);
+err_clean_m_ent:
+	media_entity_cleanup(&vcap->vdev.entity);
+err_clean_pads:
+	vimc_pads_cleanup(vcap->ved.pads);
+err_free_vcap:
+	kfree(vcap);
+
+	return ERR_PTR(ret);
+}
diff --git a/drivers/media/platform/vimc/vimc-capture.h b/drivers/media/platform/vimc/vimc-capture.h
new file mode 100644
index 0000000..bcf9fc37
--- /dev/null
+++ b/drivers/media/platform/vimc/vimc-capture.h
@@ -0,0 +1,28 @@ 
+/*
+ * vimc-capture.h Virtual Media Controller Driver
+ *
+ * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _VIMC_CAPTURE_H_
+#define _VIMC_CAPTURE_H_
+
+#include "vimc-core.h"
+
+struct vimc_ent_device *vimc_cap_create(struct v4l2_device *v4l2_dev,
+					const char *const name,
+					u16 num_pads,
+					const unsigned long *pads_flag);
+
+#endif
diff --git a/drivers/media/platform/vimc/vimc-core.c b/drivers/media/platform/vimc/vimc-core.c
new file mode 100644
index 0000000..0a2b91b
--- /dev/null
+++ b/drivers/media/platform/vimc/vimc-core.c
@@ -0,0 +1,600 @@ 
+/*
+ * vimc-core.c Virtual Media Controller Driver
+ *
+ * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <media/media-device.h>
+#include <media/v4l2-device.h>
+
+#include "vimc-capture.h"
+#include "vimc-core.h"
+#include "vimc-sensor.h"
+
+#define VIMC_PDEV_NAME "vimc"
+#define VIMC_MDEV_MODEL_NAME "VIMC MDEV"
+
+#define VIMC_ENT_LINK(src, srcpad, sink, sinkpad, link_flags) {	\
+	.src_ent = src,						\
+	.src_pad = srcpad,					\
+	.sink_ent = sink,					\
+	.sink_pad = sinkpad,					\
+	.flags = link_flags,					\
+}
+
+#define VIMC_PIX_MAP(_code, _bpp, _pixelformat) {	\
+	.code = _code,					\
+	.pixelformat = _pixelformat,			\
+	.bpp = _bpp,					\
+}
+
+struct vimc_device {
+	/* The pipeline configuration
+	 * (filled before calling vimc_device_register)
+	 */
+	const struct vimc_pipeline_config *pipe_cfg;
+
+	/* The Associated media_device parent */
+	struct media_device mdev;
+
+	/* Internal v4l2 parent device*/
+	struct v4l2_device v4l2_dev;
+
+	/* Internal topology */
+	struct vimc_ent_device **ved;
+};
+
+/**
+ * enum vimc_ent_node - Select the functionality of a node in the topology
+ * @VIMC_ENT_NODE_SENSOR:	A node of type SENSOR simulates a camera sensor
+ *				generating internal images in bayer format and
+ *				propagating those images through the pipeline
+ * @VIMC_ENT_NODE_CAPTURE:	A node of type CAPTURE is a v4l2 video_device
+ *				that exposes the received image from the
+ *				pipeline to the user space
+ * @VIMC_ENT_NODE_INPUT:	A node of type INPUT is a v4l2 video_device that
+ *				receives images from the user space and
+ *				propagates them through the pipeline
+ * @VIMC_ENT_NODE_DEBAYER:	A node type DEBAYER expects to receive a frame
+ *				in bayer format converts it to RGB
+ * @VIMC_ENT_NODE_SCALER:	A node of type SCALER scales the received image
+ *				by a given multiplier
+ *
+ * This enum is used in the entity configuration struct to allow the definition
+ * of a custom topology specifying the role of each node on it.
+ */
+enum vimc_ent_node {
+	VIMC_ENT_NODE_SENSOR,
+	VIMC_ENT_NODE_CAPTURE,
+	VIMC_ENT_NODE_INPUT,
+	VIMC_ENT_NODE_DEBAYER,
+	VIMC_ENT_NODE_SCALER,
+};
+
+/* Structure which describes individual configuration for each entity */
+struct vimc_ent_config {
+	const char *name;
+	size_t pads_qty;
+	const unsigned long *pads_flag;
+	enum vimc_ent_node node;
+};
+
+/* Structure which describes links between entities */
+struct vimc_ent_link {
+	unsigned int src_ent;
+	u16 src_pad;
+	unsigned int sink_ent;
+	u16 sink_pad;
+	u32 flags;
+};
+
+/* Structure which describes the whole topology */
+struct vimc_pipeline_config {
+	const struct vimc_ent_config *ents;
+	size_t num_ents;
+	const struct vimc_ent_link *links;
+	size_t num_links;
+};
+
+/* --------------------------------------------------------------------------
+ * Topology Configuration
+ */
+
+static const struct vimc_ent_config ent_config[] = {
+	{
+		.name = "Sensor A",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
+		.node = VIMC_ENT_NODE_SENSOR,
+	},
+	{
+		.name = "Sensor B",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
+		.node = VIMC_ENT_NODE_SENSOR,
+	},
+	{
+		.name = "Debayer A",
+		.pads_qty = 2,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
+						     MEDIA_PAD_FL_SOURCE},
+		.node = VIMC_ENT_NODE_DEBAYER,
+	},
+	{
+		.name = "Debayer B",
+		.pads_qty = 2,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
+						     MEDIA_PAD_FL_SOURCE},
+		.node = VIMC_ENT_NODE_DEBAYER,
+	},
+	{
+		.name = "Raw Capture 0",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
+		.node = VIMC_ENT_NODE_CAPTURE,
+	},
+	{
+		.name = "Raw Capture 1",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
+		.node = VIMC_ENT_NODE_CAPTURE,
+	},
+	{
+		.name = "RGB/YUV Input",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SOURCE},
+		.node = VIMC_ENT_NODE_INPUT,
+	},
+	{
+		.name = "Scaler",
+		.pads_qty = 2,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK,
+						     MEDIA_PAD_FL_SOURCE},
+		.node = VIMC_ENT_NODE_SCALER,
+	},
+	{
+		.name = "RGB/YUV Capture",
+		.pads_qty = 1,
+		.pads_flag = (const unsigned long[]){MEDIA_PAD_FL_SINK},
+		.node = VIMC_ENT_NODE_CAPTURE,
+	},
+};
+
+static const struct vimc_ent_link ent_links[] = {
+	/* Link: Sensor A (Pad 0)->(Pad 0) Debayer A */
+	VIMC_ENT_LINK(0, 0, 2, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Sensor A (Pad 0)->(Pad 0) Raw Capture 0 */
+	VIMC_ENT_LINK(0, 0, 4, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Sensor B (Pad 0)->(Pad 0) Debayer B */
+	VIMC_ENT_LINK(1, 0, 3, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Sensor B (Pad 0)->(Pad 0) Raw Capture 1 */
+	VIMC_ENT_LINK(1, 0, 5, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+	/* Link: Debayer A (Pad 1)->(Pad 0) Scaler */
+	VIMC_ENT_LINK(2, 1, 7, 0, MEDIA_LNK_FL_ENABLED),
+	/* Link: Debayer B (Pad 1)->(Pad 0) Scaler */
+	VIMC_ENT_LINK(3, 1, 7, 0, 0),
+	/* Link: RGB/YUV Input (Pad 0)->(Pad 0) Scaler */
+	VIMC_ENT_LINK(6, 0, 7, 0, 0),
+	/* Link: Scaler (Pad 1)->(Pad 0) RGB/YUV Capture */
+	VIMC_ENT_LINK(7, 1, 8, 0, MEDIA_LNK_FL_ENABLED | MEDIA_LNK_FL_IMMUTABLE),
+};
+
+static const struct vimc_pipeline_config pipe_cfg = {
+	.ents		= ent_config,
+	.num_ents	= ARRAY_SIZE(ent_config),
+	.links		= ent_links,
+	.num_links	= ARRAY_SIZE(ent_links)
+};
+
+/* -------------------------------------------------------------------------- */
+
+static void vimc_dev_release(struct device *dev)
+{}
+
+static struct platform_device vimc_pdev = {
+	.name		= VIMC_PDEV_NAME,
+	.dev.release	= vimc_dev_release,
+};
+
+const struct vimc_pix_map vimc_pix_map_list[] = {
+	/* TODO: add all missing formats */
+
+	/* RGB formats */
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_BGR888_1X24, 3, V4L2_PIX_FMT_BGR24),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_RGB888_1X24, 3, V4L2_PIX_FMT_RGB24),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_ARGB8888_1X32, 4, V4L2_PIX_FMT_ARGB32),
+
+	/* Bayer formats */
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR8_1X8, 1, V4L2_PIX_FMT_SBGGR8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG8_1X8, 1, V4L2_PIX_FMT_SGBRG8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG8_1X8, 1, V4L2_PIX_FMT_SGRBG8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB8_1X8, 1, V4L2_PIX_FMT_SRGGB8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_1X10, 2, V4L2_PIX_FMT_SBGGR10),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_1X10, 2, V4L2_PIX_FMT_SGBRG10),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_1X10, 2, V4L2_PIX_FMT_SGRBG10),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_1X10, 2, V4L2_PIX_FMT_SRGGB10),
+	/* 10bit raw bayer a-law compressed to 8 bits */
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_ALAW8_1X8, 1, V4L2_PIX_FMT_SBGGR10ALAW8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGBRG10ALAW8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_ALAW8_1X8, 1, V4L2_PIX_FMT_SGRBG10ALAW8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_ALAW8_1X8, 1, V4L2_PIX_FMT_SRGGB10ALAW8),
+	/* 10bit raw bayer DPCM compressed to 8 bits */
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR10_DPCM8_1X8, 1, V4L2_PIX_FMT_SBGGR10DPCM8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGBRG10DPCM8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG10_DPCM8_1X8, 1, V4L2_PIX_FMT_SGRBG10DPCM8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB10_DPCM8_1X8, 1, V4L2_PIX_FMT_SRGGB10DPCM8),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SBGGR12_1X12, 2, V4L2_PIX_FMT_SBGGR12),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGBRG12_1X12, 2, V4L2_PIX_FMT_SGBRG12),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SGRBG12_1X12, 2, V4L2_PIX_FMT_SGRBG12),
+	VIMC_PIX_MAP(MEDIA_BUS_FMT_SRGGB12_1X12, 2, V4L2_PIX_FMT_SRGGB12),
+
+	/* End */
+	{0, 0, 0}
+};
+
+const struct vimc_pix_map *vimc_pix_map_by_code(u32 code)
+{
+	unsigned int i;
+
+	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
+		if (vimc_pix_map_list[i].code == code)
+			return &vimc_pix_map_list[i];
+	}
+	return NULL;
+}
+
+const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat)
+{
+	unsigned int i;
+
+	for (i = 0; vimc_pix_map_list[i].bpp; i++) {
+		if (vimc_pix_map_list[i].pixelformat == pixelformat)
+			return &vimc_pix_map_list[i];
+	}
+	return NULL;
+}
+
+int vimc_propagate_frame(struct device *dev,
+			 struct media_pad *src, const void *frame)
+{
+	struct media_link *link;
+	struct vimc_device *vimc = dev_get_drvdata(dev);
+
+	if (!(src->flags & MEDIA_PAD_FL_SOURCE))
+		return -EINVAL;
+
+	/* Send this frame to all sink pads that are direct linked */
+	list_for_each_entry(link, &src->entity->links, list) {
+		if (link->source == src &&
+		    (link->flags & MEDIA_LNK_FL_ENABLED)) {
+			struct vimc_ent_device *ved;
+
+			ved = vimc->ved[link->sink->entity->use_count];
+			if (ved && ved->process_frame)
+				ved->process_frame(ved, link->sink, frame);
+		}
+	}
+
+	return 0;
+}
+
+static void vimc_device_unregister(struct vimc_device *vimc)
+{
+	unsigned int i;
+
+	/* Cleanup (only initialized) entities */
+	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
+		if (vimc->ved[i] && vimc->ved[i]->destroy)
+			vimc->ved[i]->destroy(vimc->ved[i]);
+
+		vimc->ved[i] = NULL;
+	}
+	v4l2_device_unregister(&vimc->v4l2_dev);
+
+	media_device_unregister(&vimc->mdev);
+	media_device_cleanup(&vimc->mdev);
+}
+
+/* Helper function to allocate and initialize pads */
+struct media_pad *vimc_pads_init(u16 num_pads, const unsigned long *pads_flag)
+{
+	unsigned int i;
+	struct media_pad *pads;
+
+	/* Allocate memory for the pads */
+	pads = kcalloc(num_pads, sizeof(*pads), GFP_KERNEL);
+	if (!pads)
+		return ERR_PTR(-ENOMEM);
+
+	/* Initialize the pads */
+	for (i = 0; i < num_pads; i++) {
+		pads[i].index = i;
+		pads[i].flags = pads_flag[i];
+	}
+
+	return pads;
+}
+
+/* TODO: remove this function when all the
+ * entities specific code are implemented
+ */
+static void vimc_raw_destroy(struct vimc_ent_device *ved)
+{
+	media_device_unregister_entity(ved->ent);
+
+	media_entity_cleanup(ved->ent);
+
+	vimc_pads_cleanup(ved->pads);
+
+	kfree(ved->ent);
+
+	kfree(ved);
+}
+
+/* TODO: remove this function when all the
+ * entities specific code are implemented
+ */
+static struct vimc_ent_device *vimc_raw_create(struct v4l2_device *v4l2_dev,
+					       const char *const name,
+					       u16 num_pads,
+					       const unsigned long *pads_flag)
+{
+	int ret;
+	struct vimc_ent_device *ved;
+
+	/* Allocate the main ved struct */
+	ved = kzalloc(sizeof(*ved), GFP_KERNEL);
+	if (!ved)
+		return ERR_PTR(-ENOMEM);
+
+	/* Allocate the media entity */
+	ved->ent = kzalloc(sizeof(*ved->ent), GFP_KERNEL);
+	if (!ved->ent) {
+		ret = -ENOMEM;
+		goto err_free_ved;
+	}
+
+	/* Allocate the pads */
+	ved->pads = vimc_pads_init(num_pads, pads_flag);
+	if (IS_ERR(ved->pads)) {
+		ret = PTR_ERR(ved->pads);
+		goto err_free_ent;
+	}
+
+	/* Initialize the media entity */
+	ved->ent->name = name;
+	ved->ent->function = MEDIA_ENT_F_IO_V4L;
+	ret = media_entity_pads_init(ved->ent, num_pads, ved->pads);
+	if (ret)
+		goto err_cleanup_pads;
+
+	/* Register the media entity */
+	ret = media_device_register_entity(v4l2_dev->mdev, ved->ent);
+	if (ret)
+		goto err_cleanup_entity;
+
+	/* Fill out the destroy function and return */
+	ved->destroy = vimc_raw_destroy;
+	return ved;
+
+err_cleanup_entity:
+	media_entity_cleanup(ved->ent);
+err_cleanup_pads:
+	vimc_pads_cleanup(ved->pads);
+err_free_ent:
+	kfree(ved->ent);
+err_free_ved:
+	kfree(ved);
+
+	return ERR_PTR(ret);
+}
+
+static int vimc_device_register(struct vimc_device *vimc)
+{
+	unsigned int i;
+	int ret = 0;
+
+	/* Allocate memory for the vimc_ent_devices pointers */
+	vimc->ved = devm_kcalloc(vimc->mdev.dev, vimc->pipe_cfg->num_ents,
+				 sizeof(*vimc->ved), GFP_KERNEL);
+	if (!vimc->ved)
+		return -ENOMEM;
+
+	/* Register the media device */
+	ret = media_device_register(&vimc->mdev);
+	if (ret) {
+		dev_err(vimc->mdev.dev,
+			"media device register failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	/* Link the media device within the v4l2_device */
+	vimc->v4l2_dev.mdev = &vimc->mdev;
+
+	/* Register the v4l2 struct */
+	ret = v4l2_device_register(vimc->mdev.dev, &vimc->v4l2_dev);
+	if (ret) {
+		dev_err(vimc->mdev.dev,
+			"v4l2 device register failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	/* Initialize entities */
+	for (i = 0; i < vimc->pipe_cfg->num_ents; i++) {
+		struct vimc_ent_device *(*create_func)(struct v4l2_device *,
+						       const char *const,
+						       u16,
+						       const unsigned long *);
+
+		/* Register the specific node */
+		switch (vimc->pipe_cfg->ents[i].node) {
+		case VIMC_ENT_NODE_SENSOR:
+			create_func = vimc_sen_create;
+			break;
+
+		case VIMC_ENT_NODE_CAPTURE:
+			create_func = vimc_cap_create;
+			break;
+
+		/* TODO: Instantiate the specific topology node */
+		case VIMC_ENT_NODE_INPUT:
+		case VIMC_ENT_NODE_DEBAYER:
+		case VIMC_ENT_NODE_SCALER:
+		default:
+			/* TODO: remove this when all the entities specific
+			 * code are implemented
+			 */
+			create_func = vimc_raw_create;
+			break;
+		}
+
+		vimc->ved[i] = create_func(&vimc->v4l2_dev,
+					   vimc->pipe_cfg->ents[i].name,
+					   vimc->pipe_cfg->ents[i].pads_qty,
+					   vimc->pipe_cfg->ents[i].pads_flag);
+		if (IS_ERR(vimc->ved[i])) {
+			ret = PTR_ERR(vimc->ved[i]);
+			vimc->ved[i] = NULL;
+			goto err;
+		}
+
+		/* Set use_count to keep track of the ved structure */
+		vimc->ved[i]->ent->use_count = i;
+	}
+
+	/* Initialize the links between entities */
+	for (i = 0; i < vimc->pipe_cfg->num_links; i++) {
+		const struct vimc_ent_link *link = &vimc->pipe_cfg->links[i];
+
+		ret = media_create_pad_link(vimc->ved[link->src_ent]->ent,
+					    link->src_pad,
+					    vimc->ved[link->sink_ent]->ent,
+					    link->sink_pad,
+					    link->flags);
+		if (ret)
+			goto err;
+	}
+
+	/* Expose all subdev's nodes*/
+	ret = v4l2_device_register_subdev_nodes(&vimc->v4l2_dev);
+	if (ret) {
+		dev_err(vimc->mdev.dev,
+			"vimc subdev nodes registration failed (err=%d)\n",
+			ret);
+		goto err;
+	}
+
+	return 0;
+
+err:
+	/* Destroy the so far created topology */
+	vimc_device_unregister(vimc);
+
+	return ret;
+}
+
+static int vimc_probe(struct platform_device *pdev)
+{
+	struct vimc_device *vimc;
+	int ret;
+
+	/* Prepare the vimc topology structure */
+
+	/* Allocate memory for the vimc structure */
+	vimc = devm_kzalloc(&pdev->dev, sizeof(*vimc), GFP_KERNEL);
+	if (!vimc)
+		return -ENOMEM;
+
+	/* Set the pipeline configuration struct */
+	vimc->pipe_cfg = &pipe_cfg;
+
+	/* Initialize media device */
+	strlcpy(vimc->mdev.model, VIMC_MDEV_MODEL_NAME,
+		sizeof(vimc->mdev.model));
+	vimc->mdev.dev = &pdev->dev;
+	media_device_init(&vimc->mdev);
+
+	/* Create vimc topology */
+	ret = vimc_device_register(vimc);
+	if (ret) {
+		dev_err(vimc->mdev.dev,
+			"vimc device registration failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	/* Link the topology object with the platform device object */
+	platform_set_drvdata(pdev, vimc);
+
+	return 0;
+}
+
+static int vimc_remove(struct platform_device *pdev)
+{
+	struct vimc_device *vimc;
+
+	/* Get the topology object linked with the platform device object */
+	vimc = platform_get_drvdata(pdev);
+
+	/* Destroy all the topology */
+	vimc_device_unregister(vimc);
+
+	return 0;
+}
+
+static struct platform_driver vimc_pdrv = {
+	.probe		= vimc_probe,
+	.remove		= vimc_remove,
+	.driver		= {
+		.name	= VIMC_PDEV_NAME,
+	},
+};
+
+static int __init vimc_init(void)
+{
+	int ret;
+
+	ret = platform_device_register(&vimc_pdev);
+	if (ret) {
+		dev_err(&vimc_pdev.dev,
+			"platform device registration failed (err=%d)\n", ret);
+		return ret;
+	}
+
+	ret = platform_driver_register(&vimc_pdrv);
+	if (ret) {
+		dev_err(&vimc_pdev.dev,
+			"platform driver registration failed (err=%d)\n", ret);
+
+		platform_device_unregister(&vimc_pdev);
+	}
+
+	return ret;
+}
+
+static void __exit vimc_exit(void)
+{
+	platform_driver_unregister(&vimc_pdrv);
+
+	platform_device_unregister(&vimc_pdev);
+}
+
+module_init(vimc_init);
+module_exit(vimc_exit);
+
+MODULE_DESCRIPTION("Virtual Media Controller Driver (VIMC)");
+MODULE_AUTHOR("Helen Fornazier <helen.fornazier@gmail.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/media/platform/vimc/vimc-core.h b/drivers/media/platform/vimc/vimc-core.h
new file mode 100644
index 0000000..bd7abff
--- /dev/null
+++ b/drivers/media/platform/vimc/vimc-core.h
@@ -0,0 +1,57 @@ 
+/*
+ * vimc-core.h Virtual Media Controller Driver
+ *
+ * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _VIMC_CORE_H_
+#define _VIMC_CORE_H_
+
+#include <linux/slab.h>
+#include <media/v4l2-device.h>
+
+/* Struct which matches the MEDIA_BUS_FMT_ codes with the corresponding
+ * V4L2_PIX_FMT_ fourcc pixelformat and its bytes per pixel (bpp)
+ */
+struct vimc_pix_map {
+	unsigned int code;
+	unsigned int bpp;
+	u32 pixelformat;
+};
+extern const struct vimc_pix_map vimc_pix_map_list[];
+
+struct vimc_ent_device {
+	struct media_entity *ent;
+	struct media_pad *pads;
+	void (*destroy)(struct vimc_ent_device *);
+	void (*process_frame)(struct vimc_ent_device *ved,
+			      struct media_pad *sink, const void *frame);
+};
+
+int vimc_propagate_frame(struct device *dev,
+			 struct media_pad *src, const void *frame);
+
+/* Helper functions to allocate/initialize pads and free them */
+struct media_pad *vimc_pads_init(u16 num_pads,
+				 const unsigned long *pads_flag);
+static inline void vimc_pads_cleanup(struct media_pad *pads)
+{
+	kfree(pads);
+}
+
+const struct vimc_pix_map *vimc_pix_map_by_code(u32 code);
+
+const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat);
+
+#endif
diff --git a/drivers/media/platform/vimc/vimc-sensor.c b/drivers/media/platform/vimc/vimc-sensor.c
new file mode 100644
index 0000000..174e5dc
--- /dev/null
+++ b/drivers/media/platform/vimc/vimc-sensor.c
@@ -0,0 +1,279 @@ 
+/*
+ * vimc-sensor.c Virtual Media Controller Driver
+ *
+ * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include <linux/vmalloc.h>
+#include <linux/v4l2-mediabus.h>
+#include <media/v4l2-subdev.h>
+
+#include "vimc-sensor.h"
+
+struct vimc_sen_device {
+	struct vimc_ent_device ved;
+	struct v4l2_subdev sd;
+	struct v4l2_device *v4l2_dev;
+	struct device *dev;
+	struct task_struct *kthread_sen;
+	u8 *frame;
+	/* The active format */
+	struct v4l2_mbus_framefmt mbus_format;
+	int frame_size;
+};
+
+static int vimc_sen_enum_mbus_code(struct v4l2_subdev *sd,
+				   struct v4l2_subdev_pad_config *cfg,
+				   struct v4l2_subdev_mbus_code_enum *code)
+{
+	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	/* Check if it is a valid pad */
+	if (code->pad >= vsen->sd.entity.num_pads)
+		return -EINVAL;
+
+	code->code = vsen->mbus_format.code;
+
+	return 0;
+}
+
+static int vimc_sen_enum_frame_size(struct v4l2_subdev *sd,
+				    struct v4l2_subdev_pad_config *cfg,
+				    struct v4l2_subdev_frame_size_enum *fse)
+{
+	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	/* Check if it is a valid pad */
+	if (fse->pad >= vsen->sd.entity.num_pads)
+		return -EINVAL;
+
+	/* TODO: Add support to other formats */
+	if (fse->index)
+		return -EINVAL;
+
+	/* TODO: Add support for other codes */
+	if (fse->code != vsen->mbus_format.code)
+		return -EINVAL;
+
+	fse->min_width = vsen->mbus_format.width;
+	fse->max_width = vsen->mbus_format.width;
+	fse->min_height = vsen->mbus_format.height;
+	fse->max_height = vsen->mbus_format.height;
+
+	return 0;
+}
+
+static int vimc_sen_get_fmt(struct v4l2_subdev *sd,
+			    struct v4l2_subdev_pad_config *cfg,
+			    struct v4l2_subdev_format *format)
+{
+	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	format->format = vsen->mbus_format;
+
+	return 0;
+}
+
+static const struct v4l2_subdev_pad_ops vimc_sen_pad_ops = {
+	.enum_mbus_code		= vimc_sen_enum_mbus_code,
+	.enum_frame_size	= vimc_sen_enum_frame_size,
+	.get_fmt		= vimc_sen_get_fmt,
+	/* TODO: Add support to other formats */
+	.set_fmt		= vimc_sen_get_fmt,
+};
+
+/* media operations */
+static const struct media_entity_operations vimc_sen_mops = {
+	.link_validate = v4l2_subdev_link_validate,
+};
+
+static int vimc_thread_sen(void *data)
+{
+	unsigned int i;
+	struct vimc_sen_device *vsen = data;
+
+	set_freezable();
+
+	for (;;) {
+		try_to_freeze();
+		if (kthread_should_stop())
+			break;
+
+		memset(vsen->frame, 100, vsen->frame_size);
+
+		/* Send the frame to all source pads */
+		for (i = 0; i < vsen->sd.entity.num_pads; i++)
+			vimc_propagate_frame(vsen->dev,
+					     &vsen->sd.entity.pads[i],
+					     vsen->frame);
+
+		/* 60 frames per second */
+		schedule_timeout_interruptible(HZ/60);
+	}
+
+	return 0;
+}
+
+static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
+{
+	int ret;
+	struct vimc_sen_device *vsen = v4l2_get_subdevdata(sd);
+
+	if (enable) {
+		const struct vimc_pix_map *vpix;
+
+		if (vsen->kthread_sen)
+			return -EINVAL;
+
+		/* Calculate the frame size */
+		vpix = vimc_pix_map_by_code(vsen->mbus_format.code);
+		vsen->frame_size = vsen->mbus_format.width * vpix->bpp *
+				   vsen->mbus_format.height;
+
+		/* Allocate the frame buffer. Use vmalloc to be able to
+		 * allocate a large amount of memory
+		 */
+		vsen->frame = vmalloc(vsen->frame_size);
+		if (!vsen->frame)
+			return -ENOMEM;
+
+		/* Initialize the image generator thread */
+		vsen->kthread_sen = kthread_run(vimc_thread_sen, vsen,
+						"%s-sen", vsen->v4l2_dev->name);
+		if (IS_ERR(vsen->kthread_sen)) {
+			v4l2_err(vsen->v4l2_dev, "kernel_thread() failed\n");
+			vfree(vsen->frame);
+			vsen->frame = NULL;
+			return PTR_ERR(vsen->kthread_sen);
+		}
+	} else {
+		if (!vsen->kthread_sen)
+			return -EINVAL;
+
+		/* Stop image generator */
+		ret = kthread_stop(vsen->kthread_sen);
+		vsen->kthread_sen = NULL;
+
+		vfree(vsen->frame);
+		vsen->frame = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+struct v4l2_subdev_video_ops vimc_sen_video_ops = {
+	.s_stream = vimc_sen_s_stream,
+};
+
+static const struct v4l2_subdev_ops vimc_sen_ops = {
+	.pad = &vimc_sen_pad_ops,
+	.video = &vimc_sen_video_ops,
+};
+
+static void vimc_sen_destroy(struct vimc_ent_device *ved)
+{
+	struct vimc_sen_device *vsen = container_of(ved,
+						struct vimc_sen_device, ved);
+
+	media_entity_cleanup(ved->ent);
+	v4l2_device_unregister_subdev(&vsen->sd);
+	kfree(vsen);
+}
+
+struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
+					const char *const name,
+					u16 num_pads,
+					const unsigned long *pads_flag)
+{
+	int ret;
+	unsigned int i;
+	struct vimc_sen_device *vsen;
+
+	if (!name || (num_pads && !pads_flag))
+		return ERR_PTR(-EINVAL);
+	/* check if all pads are sources */
+	for (i = 0; i < num_pads; i++)
+		if (!(pads_flag[i] & MEDIA_PAD_FL_SOURCE))
+			return ERR_PTR(-EINVAL);
+
+	/* Allocate the vsen struct */
+	vsen = kzalloc(sizeof(*vsen), GFP_KERNEL);
+	if (!vsen)
+		return ERR_PTR(-ENOMEM);
+
+	/* Link the vimc_sen_device struct with the v4l2 parent */
+	vsen->v4l2_dev = v4l2_dev;
+	/* Link the vimc_sen_device struct with the dev parent */
+	vsen->dev = v4l2_dev->dev;
+
+	/* Allocate the pads */
+	vsen->ved.pads = vimc_pads_init(num_pads, pads_flag);
+	if (IS_ERR(vsen->ved.pads)) {
+		ret = PTR_ERR(vsen->ved.pads);
+		goto err_free_vsen;
+	}
+
+	/* Initialize the media entity */
+	vsen->sd.entity.name = name;
+	ret = media_entity_pads_init(&vsen->sd.entity,
+				     num_pads, vsen->ved.pads);
+	if (ret)
+		goto err_clean_pads;
+
+	/* Set the active frame format (this is hardcoded for now) */
+	vsen->mbus_format.width = 640;
+	vsen->mbus_format.height = 480;
+	vsen->mbus_format.code = MEDIA_BUS_FMT_RGB888_1X24;
+	vsen->mbus_format.field = V4L2_FIELD_NONE;
+	vsen->mbus_format.colorspace = V4L2_COLORSPACE_SRGB;
+	vsen->mbus_format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
+	vsen->mbus_format.xfer_func = V4L2_XFER_FUNC_SRGB;
+
+	/* Fill the vimc_ent_device struct */
+	vsen->ved.destroy = vimc_sen_destroy;
+	vsen->ved.ent = &vsen->sd.entity;
+
+	/* Initialize the subdev */
+	v4l2_subdev_init(&vsen->sd, &vimc_sen_ops);
+	vsen->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
+	vsen->sd.entity.ops = &vimc_sen_mops;
+	vsen->sd.owner = THIS_MODULE;
+	strlcpy(vsen->sd.name, name, sizeof(vsen->sd.name));
+	v4l2_set_subdevdata(&vsen->sd, vsen);
+
+	/* Expose this subdev to user space */
+	vsen->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
+
+	/* Register the subdev with the v4l2 and the media framework */
+	ret = v4l2_device_register_subdev(vsen->v4l2_dev, &vsen->sd);
+	if (ret) {
+		dev_err(vsen->dev,
+			"subdev register failed (err=%d)\n", ret);
+		goto err_clean_m_ent;
+	}
+
+	return &vsen->ved;
+
+err_clean_m_ent:
+	media_entity_cleanup(&vsen->sd.entity);
+err_clean_pads:
+	vimc_pads_cleanup(vsen->ved.pads);
+err_free_vsen:
+	kfree(vsen);
+
+	return ERR_PTR(ret);
+}
diff --git a/drivers/media/platform/vimc/vimc-sensor.h b/drivers/media/platform/vimc/vimc-sensor.h
new file mode 100644
index 0000000..ffeaf6c
--- /dev/null
+++ b/drivers/media/platform/vimc/vimc-sensor.h
@@ -0,0 +1,28 @@ 
+/*
+ * vimc-sensor.h Virtual Media Controller Driver
+ *
+ * Copyright (C) 2016 Helen Koike F. <helen.fornazier@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _VIMC_SENSOR_H_
+#define _VIMC_SENSOR_H_
+
+#include "vimc-core.h"
+
+struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
+					const char *const name,
+					u16 num_pads,
+					const unsigned long *pads_flag);
+
+#endif