Message ID | 1477034705-5829-1-git-send-email-thierry.escande@collabora.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Hi Thierry, On Fri, Oct 21, 2016 at 09:25:05AM +0200, Thierry Escande wrote: > From: Pawel Osciak <posciak@chromium.org> > > When this flag is set for CAPTURE queues by the driver on calling > vb2_queue_init(), it forces the buffers on the queue to be > allocated/mapped with DMA_BIDIRECTIONAL direction flag instead of > DMA_FROM_DEVICE. This allows the device not only to write to the > buffers, but also read out from them. This may be useful e.g. for codec > hardware which may be using CAPTURE buffers as reference to decode > other buffers. > > This flag is ignored for OUTPUT queues as we don't want to allow HW to > be able to write to OUTPUT buffers. > > Signed-off-by: Pawel Osciak <posciak@chromium.org> > Tested-by: Pawel Osciak <posciak@chromium.org> > Signed-off-by: Thierry Escande <thierry.escande@collabora.com> > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 21900202..22d6105 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -194,8 +194,7 @@ static void __enqueue_in_driver(struct vb2_buffer *vb); > static int __vb2_buf_mem_alloc(struct vb2_buffer *vb) > { > struct vb2_queue *q = vb->vb2_queue; > - enum dma_data_direction dma_dir = > - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; > + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); > void *mem_priv; > int plane; > int ret = -ENOMEM; > @@ -978,8 +977,7 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const void *pb) > void *mem_priv; > unsigned int plane; > int ret = 0; > - enum dma_data_direction dma_dir = > - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; > + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); > bool reacquired = vb->planes[0].mem_priv == NULL; > > memset(planes, 0, sizeof(planes[0]) * vb->num_planes); > @@ -1096,8 +1094,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const void *pb) > void *mem_priv; > unsigned int plane; > int ret = 0; > - enum dma_data_direction dma_dir = > - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; > + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); > bool reacquired = vb->planes[0].mem_priv == NULL; > > memset(planes, 0, sizeof(planes[0]) * vb->num_planes); Please also check where dma_dir is being used especially in memory type implementation. There are several comparisons to DMA_FROM_DEVICE which will have a different result if DMA_BIDIRECTIONAL is used instead.
Hi Sakari, On 21/10/2016 09:48, Sakari Ailus wrote: > Hi Thierry, > > On Fri, Oct 21, 2016 at 09:25:05AM +0200, Thierry Escande wrote: >> From: Pawel Osciak <posciak@chromium.org> >> >> When this flag is set for CAPTURE queues by the driver on calling >> vb2_queue_init(), it forces the buffers on the queue to be >> allocated/mapped with DMA_BIDIRECTIONAL direction flag instead of >> DMA_FROM_DEVICE. This allows the device not only to write to the >> buffers, but also read out from them. This may be useful e.g. for codec >> hardware which may be using CAPTURE buffers as reference to decode >> other buffers. >> >> This flag is ignored for OUTPUT queues as we don't want to allow HW to >> be able to write to OUTPUT buffers. >> >> Signed-off-by: Pawel Osciak <posciak@chromium.org> >> Tested-by: Pawel Osciak <posciak@chromium.org> >> Signed-off-by: Thierry Escande <thierry.escande@collabora.com> >> > > Please also check where dma_dir is being used especially in memory type > implementation. There are several comparisons to DMA_FROM_DEVICE which will > have a different result if DMA_BIDIRECTIONAL is used instead. Nice catch, thanks. How about a macro like this: #define VB2_DMA_DIR_CAPTURE(d) \ ((d) == DMA_FROM_DEVICE || (d) == DMA_BIDIRECTIONAL) Regards, Thierry -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Thierry, On Fri, Oct 21, 2016 at 10:53:22AM +0200, Thierry Escande wrote: > #define VB2_DMA_DIR_CAPTURE(d) \ > ((d) == DMA_FROM_DEVICE || (d) == DMA_BIDIRECTIONAL) That looks good to me.
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 21900202..22d6105 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -194,8 +194,7 @@ static void __enqueue_in_driver(struct vb2_buffer *vb); static int __vb2_buf_mem_alloc(struct vb2_buffer *vb) { struct vb2_queue *q = vb->vb2_queue; - enum dma_data_direction dma_dir = - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); void *mem_priv; int plane; int ret = -ENOMEM; @@ -978,8 +977,7 @@ static int __qbuf_userptr(struct vb2_buffer *vb, const void *pb) void *mem_priv; unsigned int plane; int ret = 0; - enum dma_data_direction dma_dir = - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); bool reacquired = vb->planes[0].mem_priv == NULL; memset(planes, 0, sizeof(planes[0]) * vb->num_planes); @@ -1096,8 +1094,7 @@ static int __qbuf_dmabuf(struct vb2_buffer *vb, const void *pb) void *mem_priv; unsigned int plane; int ret = 0; - enum dma_data_direction dma_dir = - q->is_output ? DMA_TO_DEVICE : DMA_FROM_DEVICE; + enum dma_data_direction dma_dir = VB2_DMA_DIR(q); bool reacquired = vb->planes[0].mem_priv == NULL; memset(planes, 0, sizeof(planes[0]) * vb->num_planes); diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h index ac5898a..a6cfdfb 100644 --- a/include/media/videobuf2-core.h +++ b/include/media/videobuf2-core.h @@ -433,6 +433,9 @@ struct vb2_buf_ops { * @quirk_poll_must_check_waiting_for_buffers: Return POLLERR at poll when QBUF * has not been called. This is a vb1 idiom that has been adopted * also by vb2. + * @capture_dma_bidirectional: use DMA_BIDIRECTIONAL for CAPTURE buffers; this + * allows HW to read from the CAPTURE buffers in + * addition to writing; ignored for OUTPUT queues. * @lock: pointer to a mutex that protects the vb2_queue struct. The * driver can set this to a mutex to let the v4l2 core serialize * the queuing ioctls. If the driver wants to handle locking @@ -499,6 +502,7 @@ struct vb2_queue { unsigned fileio_write_immediately:1; unsigned allow_zero_bytesused:1; unsigned quirk_poll_must_check_waiting_for_buffers:1; + unsigned capture_dma_bidirectional:1; struct mutex *lock; void *owner; @@ -554,6 +558,17 @@ struct vb2_queue { #endif }; +/* + * Returns the corresponding DMA direction given the vb2_queue type (capture or + * output). Returns DMA_BIDIRECTIONAL for capture buffers if the vb2_queue field + * capture_dma_bidirectional is set by the driver. + */ +#define VB2_DMA_DIR(q) (V4L2_TYPE_IS_OUTPUT((q)->type) \ + ? DMA_TO_DEVICE \ + : (q)->capture_dma_bidirectional \ + ? DMA_BIDIRECTIONAL \ + : DMA_FROM_DEVICE) + /** * vb2_plane_vaddr() - Return a kernel virtual address of a given plane * @vb: vb2_buffer to which the plane in question belongs to