Hi Thierry,
On Fri, Oct 21, 2016 at 09:25:05AM +0200, Thierry Escande wrote:
> From: Pawel Osciak <posciak@xxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxx>
> Tested-by: Pawel Osciak <posciak@xxxxxxxxxxxx>
> Signed-off-by: Thierry Escande <thierry.escande@xxxxxxxxxxxxx>
>
> 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.
--
Sakari Ailus
e-mail: sakari.ailus@xxxxxx XMPP: sailus@xxxxxxxxxxxxxx
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
