diff mbox

[1/2,media] v4l2-mc: add a generic function to create the media graph

Message ID 6e3da35783650a6e555d20524421f4549d919821.1454665849.git.mchehab@osg.samsung.com (mailing list archive)
State New, archived
Headers show

Commit Message

Mauro Carvalho Chehab Feb. 5, 2016, 9:51 a.m. UTC
The em28xx_v4l2_create_media_graph() is almost generic enough to
be at the core, as an ancillary function. Make it even more generic,
by getting rid of em28xx-specific code, relying only at the
media_device, in order to discover all entities found on PC-customer's
hardware and add it at the V4L2 core.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
---
 drivers/media/v4l2-core/Makefile  |   1 +
 drivers/media/v4l2-core/v4l2-mc.c | 181 ++++++++++++++++++++++++++++++++++++++
 include/media/v4l2-mc.h           |  24 +++++
 3 files changed, 206 insertions(+)
 create mode 100644 drivers/media/v4l2-core/v4l2-mc.c

Comments

Shuah Khan Feb. 5, 2016, 2:25 p.m. UTC | #1
On 02/05/2016 02:51 AM, Mauro Carvalho Chehab wrote:
> The em28xx_v4l2_create_media_graph() is almost generic enough to
> be at the core, as an ancillary function. Make it even more generic,
> by getting rid of em28xx-specific code, relying only at the
> media_device, in order to discover all entities found on PC-customer's
> hardware and add it at the V4L2 core.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> ---
>  drivers/media/v4l2-core/Makefile  |   1 +
>  drivers/media/v4l2-core/v4l2-mc.c | 181 ++++++++++++++++++++++++++++++++++++++
>  include/media/v4l2-mc.h           |  24 +++++
>  3 files changed, 206 insertions(+)
>  create mode 100644 drivers/media/v4l2-core/v4l2-mc.c


Hi Mauro,

The following patch I sent a couple of days ago creates
this file rivers/media/v4l2-core/v4l2-mc.c

You had some minor comments on that patch and I am working
on addressing them.

[PATCH v2 07/22] media: v4l-core add enable/disable source common interfaces
https://lkml.org/lkml/2016/2/3/1500

Looks like you added it in your patch. This would lead a conflict
between our patches. How do you propose to resolve this?

thanks,
-- Shuah


> 
> diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
> index 1dc8bba2b198..795a5352761d 100644
> --- a/drivers/media/v4l2-core/Makefile
> +++ b/drivers/media/v4l2-core/Makefile
> @@ -16,6 +16,7 @@ endif
>  ifeq ($(CONFIG_TRACEPOINTS),y)
>    videodev-objs += vb2-trace.o v4l2-trace.o
>  endif
> +videodev-$(CONFIG_MEDIA_CONTROLLER) += v4l2-mc.o
>  
>  obj-$(CONFIG_VIDEO_V4L2) += videodev.o
>  obj-$(CONFIG_VIDEO_V4L2) += v4l2-common.o
> diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
> new file mode 100644
> index 000000000000..7276dbbbe830
> --- /dev/null
> +++ b/drivers/media/v4l2-core/v4l2-mc.c
> @@ -0,0 +1,181 @@
> +/*
> + * Media Controller ancillary functions
> + *
> + * (c) 2016 Mauro Carvalho Chehab <mchehab@osg.samsung.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/module.h>
> +#include <media/media-entity.h>
> +#include <media/v4l2-mc.h>
> +
> +int v4l2_mc_create_media_graph(struct media_device *mdev)
> +
> +{
> +	struct media_entity *entity;
> +	struct media_entity *if_vid = NULL, *if_aud = NULL, *sensor = NULL;
> +	struct media_entity *tuner = NULL, *decoder = NULL;
> +	struct media_entity *io_v4l = NULL, *io_vbi = NULL, *io_swradio = NULL;
> +	bool is_webcam = false;
> +	int ret;
> +
> +	if (!mdev)
> +		return 0;
> +
> +	media_device_for_each_entity(entity, mdev) {
> +		switch (entity->function) {
> +		case MEDIA_ENT_F_IF_VID_DECODER:
> +			if_vid = entity;
> +			break;
> +		case MEDIA_ENT_F_IF_AUD_DECODER:
> +			if_aud = entity;
> +			break;
> +		case MEDIA_ENT_F_TUNER:
> +			tuner = entity;
> +			break;
> +		case MEDIA_ENT_F_ATV_DECODER:
> +			decoder = entity;
> +			break;
> +		case MEDIA_ENT_F_IO_V4L:
> +			io_v4l = entity;
> +			break;
> +		case MEDIA_ENT_F_IO_VBI:
> +			io_vbi = entity;
> +			break;
> +		case MEDIA_ENT_F_IO_SWRADIO:
> +			io_swradio = entity;
> +			break;
> +		case MEDIA_ENT_F_CAM_SENSOR:
> +			sensor = entity;
> +			is_webcam = true;
> +			break;
> +		}
> +	}
> +
> +	/* It should have at least one I/O entity */
> +	if (!io_v4l && !io_vbi && !io_swradio)
> +		return -EINVAL;
> +
> +	/*
> +	 * Here, webcams are modeled on a very simple way: the sensor is
> +	 * connected directly to the I/O entity. All dirty details, like
> +	 * scaler and crop HW are hidden. While such mapping is not enough
> +	 * for mc-centric hardware, it is enough for v4l2 interface centric
> +	 * PC-consumer's hardware.
> +	 */
> +	if (is_webcam) {
> +		if (!io_v4l)
> +			return -EINVAL;
> +
> +		media_device_for_each_entity(entity, mdev) {
> +			if (entity->function != MEDIA_ENT_F_CAM_SENSOR)
> +				continue;
> +			ret = media_create_pad_link(entity, 0,
> +						    io_v4l, 0,
> +						    MEDIA_LNK_FL_ENABLED);
> +			if (ret)
> +				return ret;
> +		}
> +		if (!decoder)
> +			return 0;
> +	}
> +
> +	/* The device isn't a webcam. So, it should have a decoder */
> +	if (!decoder)
> +		return -EINVAL;
> +
> +	/* Link the tuner and IF video output pads */
> +	if (tuner) {
> +		if (if_vid) {
> +			ret = media_create_pad_link(tuner, TUNER_PAD_OUTPUT,
> +						    if_vid,
> +						    IF_VID_DEC_PAD_IF_INPUT,
> +						    MEDIA_LNK_FL_ENABLED);
> +			if (ret)
> +				return ret;
> +			ret = media_create_pad_link(if_vid, IF_VID_DEC_PAD_OUT,
> +						decoder, DEMOD_PAD_IF_INPUT,
> +						MEDIA_LNK_FL_ENABLED);
> +			if (ret)
> +				return ret;
> +		} else {
> +			ret = media_create_pad_link(tuner, TUNER_PAD_OUTPUT,
> +						decoder, DEMOD_PAD_IF_INPUT,
> +						MEDIA_LNK_FL_ENABLED);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		if (if_aud) {
> +			ret = media_create_pad_link(tuner, TUNER_PAD_AUD_OUT,
> +						    if_aud,
> +						    IF_AUD_DEC_PAD_IF_INPUT,
> +						    MEDIA_LNK_FL_ENABLED);
> +			if (ret)
> +				return ret;
> +		} else {
> +			if_aud = tuner;
> +		}
> +
> +	}
> +
> +	/* Create demod to V4L, VBI and SDR radio links */
> +	if (io_v4l) {
> +		ret = media_create_pad_link(decoder, DEMOD_PAD_VID_OUT,
> +					io_v4l, 0,
> +					MEDIA_LNK_FL_ENABLED);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (io_swradio) {
> +		ret = media_create_pad_link(decoder, DEMOD_PAD_VID_OUT,
> +					io_swradio, 0,
> +					MEDIA_LNK_FL_ENABLED);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (io_vbi) {
> +		ret = media_create_pad_link(decoder, DEMOD_PAD_VBI_OUT,
> +					    io_vbi, 0,
> +					    MEDIA_LNK_FL_ENABLED);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	/* Create links for the media connectors */
> +	media_device_for_each_entity(entity, mdev) {
> +		switch (entity->function) {
> +		case MEDIA_ENT_F_CONN_RF:
> +			if (!tuner)
> +				continue;
> +
> +			ret = media_create_pad_link(entity, 0, tuner,
> +						    TUNER_PAD_RF_INPUT,
> +						    MEDIA_LNK_FL_ENABLED);
> +			break;
> +		case MEDIA_ENT_F_CONN_SVIDEO:
> +		case MEDIA_ENT_F_CONN_COMPOSITE:
> +		case MEDIA_ENT_F_CONN_TEST:
> +			ret = media_create_pad_link(entity, 0, decoder,
> +						    DEMOD_PAD_IF_INPUT, 0);
> +			break;
> +		default:
> +			continue;
> +		}
> +		if (ret)
> +			return ret;
> +	}
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_mc_create_media_graph);
> diff --git a/include/media/v4l2-mc.h b/include/media/v4l2-mc.h
> index df115195690e..3097493e6cf1 100644
> --- a/include/media/v4l2-mc.h
> +++ b/include/media/v4l2-mc.h
> @@ -14,6 +14,8 @@
>   * GNU General Public License for more details.
>   */
>  
> +#include <media/media-device.h>
> +
>  /**
>   * enum tuner_pad_index - tuner pad index for MEDIA_ENT_F_TUNER
>   *
> @@ -89,3 +91,25 @@ enum demod_pad_index {
>  	DEMOD_PAD_VBI_OUT,
>  	DEMOD_NUM_PADS
>  };
> +
> +/**
> + * v4l2_mc_create_media_graph() - create Media Controller links at the graph.
> + *
> + * @mdev:	pointer to the &media_device struct.
> + *
> + * Add links between the entities commonly found on PC customer's hardware at
> + * the V4L2 side: camera sensors, audio and video PLL-IF decoders, tuners,
> + * analog TV decoder and I/O entities (video, VBI and Software Defined Radio).
> + * NOTE: webcams are modeled on a very simple way: the sensor is
> + * connected directly to the I/O entity. All dirty details, like
> + * scaler and crop HW are hidden. While such mapping is enough for v4l2
> + * interface centric PC-consumer's hardware, V4L2 subdev centric camera
> + * hardware should not use this routine, as it will not build the right graph.
> + */
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +int v4l2_mc_create_media_graph(struct media_device *mdev);
> +#else
> +static inline int v4l2_mc_create_media_graph(struct media_device *mdev) {
> +	return 0;
> +}
> +#endif
>
Mauro Carvalho Chehab Feb. 5, 2016, 3:36 p.m. UTC | #2
Em Fri, 05 Feb 2016 07:25:29 -0700
Shuah Khan <shuahkh@osg.samsung.com> escreveu:

> On 02/05/2016 02:51 AM, Mauro Carvalho Chehab wrote:
> > The em28xx_v4l2_create_media_graph() is almost generic enough to
> > be at the core, as an ancillary function. Make it even more generic,
> > by getting rid of em28xx-specific code, relying only at the
> > media_device, in order to discover all entities found on PC-customer's
> > hardware and add it at the V4L2 core.
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
> > ---
> >  drivers/media/v4l2-core/Makefile  |   1 +
> >  drivers/media/v4l2-core/v4l2-mc.c | 181 ++++++++++++++++++++++++++++++++++++++
> >  include/media/v4l2-mc.h           |  24 +++++
> >  3 files changed, 206 insertions(+)
> >  create mode 100644 drivers/media/v4l2-core/v4l2-mc.c  
> 
> 
> Hi Mauro,
> 
> The following patch I sent a couple of days ago creates
> this file rivers/media/v4l2-core/v4l2-mc.c
> 
> You had some minor comments on that patch and I am working
> on addressing them.
> 
> [PATCH v2 07/22] media: v4l-core add enable/disable source common interfaces
> https://lkml.org/lkml/2016/2/3/1500
> 
> Looks like you added it in your patch. This would lead a conflict
> between our patches. How do you propose to resolve this?

Don't worry with that. As it is just line additions, such conflict is
easily handle. No need to rebase.

> 
> thanks,
> -- Shuah
> 
> 
> > 
> > diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
> > index 1dc8bba2b198..795a5352761d 100644
> > --- a/drivers/media/v4l2-core/Makefile
> > +++ b/drivers/media/v4l2-core/Makefile
> > @@ -16,6 +16,7 @@ endif
> >  ifeq ($(CONFIG_TRACEPOINTS),y)
> >    videodev-objs += vb2-trace.o v4l2-trace.o
> >  endif
> > +videodev-$(CONFIG_MEDIA_CONTROLLER) += v4l2-mc.o
> >  
> >  obj-$(CONFIG_VIDEO_V4L2) += videodev.o
> >  obj-$(CONFIG_VIDEO_V4L2) += v4l2-common.o
> > diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
> > new file mode 100644
> > index 000000000000..7276dbbbe830
> > --- /dev/null
> > +++ b/drivers/media/v4l2-core/v4l2-mc.c
> > @@ -0,0 +1,181 @@
> > +/*
> > + * Media Controller ancillary functions
> > + *
> > + * (c) 2016 Mauro Carvalho Chehab <mchehab@osg.samsung.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/module.h>
> > +#include <media/media-entity.h>
> > +#include <media/v4l2-mc.h>
> > +
> > +int v4l2_mc_create_media_graph(struct media_device *mdev)
> > +
> > +{
> > +	struct media_entity *entity;
> > +	struct media_entity *if_vid = NULL, *if_aud = NULL, *sensor = NULL;
> > +	struct media_entity *tuner = NULL, *decoder = NULL;
> > +	struct media_entity *io_v4l = NULL, *io_vbi = NULL, *io_swradio = NULL;
> > +	bool is_webcam = false;
> > +	int ret;
> > +
> > +	if (!mdev)
> > +		return 0;
> > +
> > +	media_device_for_each_entity(entity, mdev) {
> > +		switch (entity->function) {
> > +		case MEDIA_ENT_F_IF_VID_DECODER:
> > +			if_vid = entity;
> > +			break;
> > +		case MEDIA_ENT_F_IF_AUD_DECODER:
> > +			if_aud = entity;
> > +			break;
> > +		case MEDIA_ENT_F_TUNER:
> > +			tuner = entity;
> > +			break;
> > +		case MEDIA_ENT_F_ATV_DECODER:
> > +			decoder = entity;
> > +			break;
> > +		case MEDIA_ENT_F_IO_V4L:
> > +			io_v4l = entity;
> > +			break;
> > +		case MEDIA_ENT_F_IO_VBI:
> > +			io_vbi = entity;
> > +			break;
> > +		case MEDIA_ENT_F_IO_SWRADIO:
> > +			io_swradio = entity;
> > +			break;
> > +		case MEDIA_ENT_F_CAM_SENSOR:
> > +			sensor = entity;
> > +			is_webcam = true;
> > +			break;
> > +		}
> > +	}
> > +
> > +	/* It should have at least one I/O entity */
> > +	if (!io_v4l && !io_vbi && !io_swradio)
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * Here, webcams are modeled on a very simple way: the sensor is
> > +	 * connected directly to the I/O entity. All dirty details, like
> > +	 * scaler and crop HW are hidden. While such mapping is not enough
> > +	 * for mc-centric hardware, it is enough for v4l2 interface centric
> > +	 * PC-consumer's hardware.
> > +	 */
> > +	if (is_webcam) {
> > +		if (!io_v4l)
> > +			return -EINVAL;
> > +
> > +		media_device_for_each_entity(entity, mdev) {
> > +			if (entity->function != MEDIA_ENT_F_CAM_SENSOR)
> > +				continue;
> > +			ret = media_create_pad_link(entity, 0,
> > +						    io_v4l, 0,
> > +						    MEDIA_LNK_FL_ENABLED);
> > +			if (ret)
> > +				return ret;
> > +		}
> > +		if (!decoder)
> > +			return 0;
> > +	}
> > +
> > +	/* The device isn't a webcam. So, it should have a decoder */
> > +	if (!decoder)
> > +		return -EINVAL;
> > +
> > +	/* Link the tuner and IF video output pads */
> > +	if (tuner) {
> > +		if (if_vid) {
> > +			ret = media_create_pad_link(tuner, TUNER_PAD_OUTPUT,
> > +						    if_vid,
> > +						    IF_VID_DEC_PAD_IF_INPUT,
> > +						    MEDIA_LNK_FL_ENABLED);
> > +			if (ret)
> > +				return ret;
> > +			ret = media_create_pad_link(if_vid, IF_VID_DEC_PAD_OUT,
> > +						decoder, DEMOD_PAD_IF_INPUT,
> > +						MEDIA_LNK_FL_ENABLED);
> > +			if (ret)
> > +				return ret;
> > +		} else {
> > +			ret = media_create_pad_link(tuner, TUNER_PAD_OUTPUT,
> > +						decoder, DEMOD_PAD_IF_INPUT,
> > +						MEDIA_LNK_FL_ENABLED);
> > +			if (ret)
> > +				return ret;
> > +		}
> > +
> > +		if (if_aud) {
> > +			ret = media_create_pad_link(tuner, TUNER_PAD_AUD_OUT,
> > +						    if_aud,
> > +						    IF_AUD_DEC_PAD_IF_INPUT,
> > +						    MEDIA_LNK_FL_ENABLED);
> > +			if (ret)
> > +				return ret;
> > +		} else {
> > +			if_aud = tuner;
> > +		}
> > +
> > +	}
> > +
> > +	/* Create demod to V4L, VBI and SDR radio links */
> > +	if (io_v4l) {
> > +		ret = media_create_pad_link(decoder, DEMOD_PAD_VID_OUT,
> > +					io_v4l, 0,
> > +					MEDIA_LNK_FL_ENABLED);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	if (io_swradio) {
> > +		ret = media_create_pad_link(decoder, DEMOD_PAD_VID_OUT,
> > +					io_swradio, 0,
> > +					MEDIA_LNK_FL_ENABLED);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	if (io_vbi) {
> > +		ret = media_create_pad_link(decoder, DEMOD_PAD_VBI_OUT,
> > +					    io_vbi, 0,
> > +					    MEDIA_LNK_FL_ENABLED);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +
> > +	/* Create links for the media connectors */
> > +	media_device_for_each_entity(entity, mdev) {
> > +		switch (entity->function) {
> > +		case MEDIA_ENT_F_CONN_RF:
> > +			if (!tuner)
> > +				continue;
> > +
> > +			ret = media_create_pad_link(entity, 0, tuner,
> > +						    TUNER_PAD_RF_INPUT,
> > +						    MEDIA_LNK_FL_ENABLED);
> > +			break;
> > +		case MEDIA_ENT_F_CONN_SVIDEO:
> > +		case MEDIA_ENT_F_CONN_COMPOSITE:
> > +		case MEDIA_ENT_F_CONN_TEST:
> > +			ret = media_create_pad_link(entity, 0, decoder,
> > +						    DEMOD_PAD_IF_INPUT, 0);
> > +			break;
> > +		default:
> > +			continue;
> > +		}
> > +		if (ret)
> > +			return ret;
> > +	}
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(v4l2_mc_create_media_graph);
> > diff --git a/include/media/v4l2-mc.h b/include/media/v4l2-mc.h
> > index df115195690e..3097493e6cf1 100644
> > --- a/include/media/v4l2-mc.h
> > +++ b/include/media/v4l2-mc.h
> > @@ -14,6 +14,8 @@
> >   * GNU General Public License for more details.
> >   */
> >  
> > +#include <media/media-device.h>
> > +
> >  /**
> >   * enum tuner_pad_index - tuner pad index for MEDIA_ENT_F_TUNER
> >   *
> > @@ -89,3 +91,25 @@ enum demod_pad_index {
> >  	DEMOD_PAD_VBI_OUT,
> >  	DEMOD_NUM_PADS
> >  };
> > +
> > +/**
> > + * v4l2_mc_create_media_graph() - create Media Controller links at the graph.
> > + *
> > + * @mdev:	pointer to the &media_device struct.
> > + *
> > + * Add links between the entities commonly found on PC customer's hardware at
> > + * the V4L2 side: camera sensors, audio and video PLL-IF decoders, tuners,
> > + * analog TV decoder and I/O entities (video, VBI and Software Defined Radio).
> > + * NOTE: webcams are modeled on a very simple way: the sensor is
> > + * connected directly to the I/O entity. All dirty details, like
> > + * scaler and crop HW are hidden. While such mapping is enough for v4l2
> > + * interface centric PC-consumer's hardware, V4L2 subdev centric camera
> > + * hardware should not use this routine, as it will not build the right graph.
> > + */
> > +#ifdef CONFIG_MEDIA_CONTROLLER
> > +int v4l2_mc_create_media_graph(struct media_device *mdev);
> > +#else
> > +static inline int v4l2_mc_create_media_graph(struct media_device *mdev) {
> > +	return 0;
> > +}
> > +#endif
> >   
> 
> 
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diff mbox

Patch

diff --git a/drivers/media/v4l2-core/Makefile b/drivers/media/v4l2-core/Makefile
index 1dc8bba2b198..795a5352761d 100644
--- a/drivers/media/v4l2-core/Makefile
+++ b/drivers/media/v4l2-core/Makefile
@@ -16,6 +16,7 @@  endif
 ifeq ($(CONFIG_TRACEPOINTS),y)
   videodev-objs += vb2-trace.o v4l2-trace.o
 endif
+videodev-$(CONFIG_MEDIA_CONTROLLER) += v4l2-mc.o
 
 obj-$(CONFIG_VIDEO_V4L2) += videodev.o
 obj-$(CONFIG_VIDEO_V4L2) += v4l2-common.o
diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
new file mode 100644
index 000000000000..7276dbbbe830
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-mc.c
@@ -0,0 +1,181 @@ 
+/*
+ * Media Controller ancillary functions
+ *
+ * (c) 2016 Mauro Carvalho Chehab <mchehab@osg.samsung.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/module.h>
+#include <media/media-entity.h>
+#include <media/v4l2-mc.h>
+
+int v4l2_mc_create_media_graph(struct media_device *mdev)
+
+{
+	struct media_entity *entity;
+	struct media_entity *if_vid = NULL, *if_aud = NULL, *sensor = NULL;
+	struct media_entity *tuner = NULL, *decoder = NULL;
+	struct media_entity *io_v4l = NULL, *io_vbi = NULL, *io_swradio = NULL;
+	bool is_webcam = false;
+	int ret;
+
+	if (!mdev)
+		return 0;
+
+	media_device_for_each_entity(entity, mdev) {
+		switch (entity->function) {
+		case MEDIA_ENT_F_IF_VID_DECODER:
+			if_vid = entity;
+			break;
+		case MEDIA_ENT_F_IF_AUD_DECODER:
+			if_aud = entity;
+			break;
+		case MEDIA_ENT_F_TUNER:
+			tuner = entity;
+			break;
+		case MEDIA_ENT_F_ATV_DECODER:
+			decoder = entity;
+			break;
+		case MEDIA_ENT_F_IO_V4L:
+			io_v4l = entity;
+			break;
+		case MEDIA_ENT_F_IO_VBI:
+			io_vbi = entity;
+			break;
+		case MEDIA_ENT_F_IO_SWRADIO:
+			io_swradio = entity;
+			break;
+		case MEDIA_ENT_F_CAM_SENSOR:
+			sensor = entity;
+			is_webcam = true;
+			break;
+		}
+	}
+
+	/* It should have at least one I/O entity */
+	if (!io_v4l && !io_vbi && !io_swradio)
+		return -EINVAL;
+
+	/*
+	 * Here, webcams are modeled on a very simple way: the sensor is
+	 * connected directly to the I/O entity. All dirty details, like
+	 * scaler and crop HW are hidden. While such mapping is not enough
+	 * for mc-centric hardware, it is enough for v4l2 interface centric
+	 * PC-consumer's hardware.
+	 */
+	if (is_webcam) {
+		if (!io_v4l)
+			return -EINVAL;
+
+		media_device_for_each_entity(entity, mdev) {
+			if (entity->function != MEDIA_ENT_F_CAM_SENSOR)
+				continue;
+			ret = media_create_pad_link(entity, 0,
+						    io_v4l, 0,
+						    MEDIA_LNK_FL_ENABLED);
+			if (ret)
+				return ret;
+		}
+		if (!decoder)
+			return 0;
+	}
+
+	/* The device isn't a webcam. So, it should have a decoder */
+	if (!decoder)
+		return -EINVAL;
+
+	/* Link the tuner and IF video output pads */
+	if (tuner) {
+		if (if_vid) {
+			ret = media_create_pad_link(tuner, TUNER_PAD_OUTPUT,
+						    if_vid,
+						    IF_VID_DEC_PAD_IF_INPUT,
+						    MEDIA_LNK_FL_ENABLED);
+			if (ret)
+				return ret;
+			ret = media_create_pad_link(if_vid, IF_VID_DEC_PAD_OUT,
+						decoder, DEMOD_PAD_IF_INPUT,
+						MEDIA_LNK_FL_ENABLED);
+			if (ret)
+				return ret;
+		} else {
+			ret = media_create_pad_link(tuner, TUNER_PAD_OUTPUT,
+						decoder, DEMOD_PAD_IF_INPUT,
+						MEDIA_LNK_FL_ENABLED);
+			if (ret)
+				return ret;
+		}
+
+		if (if_aud) {
+			ret = media_create_pad_link(tuner, TUNER_PAD_AUD_OUT,
+						    if_aud,
+						    IF_AUD_DEC_PAD_IF_INPUT,
+						    MEDIA_LNK_FL_ENABLED);
+			if (ret)
+				return ret;
+		} else {
+			if_aud = tuner;
+		}
+
+	}
+
+	/* Create demod to V4L, VBI and SDR radio links */
+	if (io_v4l) {
+		ret = media_create_pad_link(decoder, DEMOD_PAD_VID_OUT,
+					io_v4l, 0,
+					MEDIA_LNK_FL_ENABLED);
+		if (ret)
+			return ret;
+	}
+
+	if (io_swradio) {
+		ret = media_create_pad_link(decoder, DEMOD_PAD_VID_OUT,
+					io_swradio, 0,
+					MEDIA_LNK_FL_ENABLED);
+		if (ret)
+			return ret;
+	}
+
+	if (io_vbi) {
+		ret = media_create_pad_link(decoder, DEMOD_PAD_VBI_OUT,
+					    io_vbi, 0,
+					    MEDIA_LNK_FL_ENABLED);
+		if (ret)
+			return ret;
+	}
+
+	/* Create links for the media connectors */
+	media_device_for_each_entity(entity, mdev) {
+		switch (entity->function) {
+		case MEDIA_ENT_F_CONN_RF:
+			if (!tuner)
+				continue;
+
+			ret = media_create_pad_link(entity, 0, tuner,
+						    TUNER_PAD_RF_INPUT,
+						    MEDIA_LNK_FL_ENABLED);
+			break;
+		case MEDIA_ENT_F_CONN_SVIDEO:
+		case MEDIA_ENT_F_CONN_COMPOSITE:
+		case MEDIA_ENT_F_CONN_TEST:
+			ret = media_create_pad_link(entity, 0, decoder,
+						    DEMOD_PAD_IF_INPUT, 0);
+			break;
+		default:
+			continue;
+		}
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_mc_create_media_graph);
diff --git a/include/media/v4l2-mc.h b/include/media/v4l2-mc.h
index df115195690e..3097493e6cf1 100644
--- a/include/media/v4l2-mc.h
+++ b/include/media/v4l2-mc.h
@@ -14,6 +14,8 @@ 
  * GNU General Public License for more details.
  */
 
+#include <media/media-device.h>
+
 /**
  * enum tuner_pad_index - tuner pad index for MEDIA_ENT_F_TUNER
  *
@@ -89,3 +91,25 @@  enum demod_pad_index {
 	DEMOD_PAD_VBI_OUT,
 	DEMOD_NUM_PADS
 };
+
+/**
+ * v4l2_mc_create_media_graph() - create Media Controller links at the graph.
+ *
+ * @mdev:	pointer to the &media_device struct.
+ *
+ * Add links between the entities commonly found on PC customer's hardware at
+ * the V4L2 side: camera sensors, audio and video PLL-IF decoders, tuners,
+ * analog TV decoder and I/O entities (video, VBI and Software Defined Radio).
+ * NOTE: webcams are modeled on a very simple way: the sensor is
+ * connected directly to the I/O entity. All dirty details, like
+ * scaler and crop HW are hidden. While such mapping is enough for v4l2
+ * interface centric PC-consumer's hardware, V4L2 subdev centric camera
+ * hardware should not use this routine, as it will not build the right graph.
+ */
+#ifdef CONFIG_MEDIA_CONTROLLER
+int v4l2_mc_create_media_graph(struct media_device *mdev);
+#else
+static inline int v4l2_mc_create_media_graph(struct media_device *mdev) {
+	return 0;
+}
+#endif