Hi Thierry, On Fri, Oct 21, 2016 at 09:25:05AM +0200, Thierry Escande wrote: > From: Pawel Osciak <[email protected]> > > 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 <[email protected]> > Tested-by: Pawel Osciak <[email protected]> > Signed-off-by: Thierry Escande <[email protected]> > > 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: [email protected] XMPP: [email protected]
