Currently the dma-buf is unmapped when the buffer is dequeued by userspace
but it's not used anymore after the driver finished processing the buffer.
So instead of doing the dma-buf unmapping in __vb2_dqbuf(), it can be made
in vb2_buffer_done() after the driver notified that buf processing is done.
Decoupling the buffer dequeue from the dma-buf unmapping has also the side
effect of making possible to add dma-buf fence support in the future since
the buffer could be dequeued even before the driver has finished using it.
Signed-off-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
---
Hello,
I've tested this patch doing DMA buffer sharing between a
vivid input and output device with both v4l2-ctl and gst:
$ v4l2-ctl -d0 -e1 --stream-dmabuf --stream-out-mmap
$ v4l2-ctl -d0 -e1 --stream-mmap --stream-out-dmabuf
$ gst-launch-1.0 v4l2src device=/dev/video0 io-mode=dmabuf ! v4l2sink device=/dev/video1 io-mode=dmabuf-import
And I didn't find any issues but more testing will be appreciated.
Best regards,
Javier
drivers/media/v4l2-core/videobuf2-core.c | 34 +++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 12 deletions(-)
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 7128b09810be..973331efaf79 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -958,6 +958,22 @@ void *vb2_plane_cookie(struct vb2_buffer *vb, unsigned int plane_no)
EXPORT_SYMBOL_GPL(vb2_plane_cookie);
/**
+ * __vb2_unmap_dmabuf() - unmap dma-buf attached to buffer planes
+ */
+static void __vb2_unmap_dmabuf(struct vb2_buffer *vb)
+{
+ int i;
+
+ for (i = 0; i < vb->num_planes; ++i) {
+ if (!vb->planes[i].dbuf_mapped)
+ continue;
+ call_void_memop(vb, unmap_dmabuf,
+ vb->planes[i].mem_priv);
+ vb->planes[i].dbuf_mapped = 0;
+ }
+}
+
+/**
* vb2_buffer_done() - inform videobuf that an operation on a buffer is finished
* @vb: vb2_buffer returned from the driver
* @state: either VB2_BUF_STATE_DONE if the operation finished successfully,
@@ -1028,6 +1044,9 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
__enqueue_in_driver(vb);
return;
default:
+ if (q->memory == VB2_MEMORY_DMABUF)
+ __vb2_unmap_dmabuf(vb);
+
/* Inform any processes that may be waiting for buffers */
wake_up(&q->done_wq);
break;
@@ -1708,23 +1727,11 @@ EXPORT_SYMBOL_GPL(vb2_wait_for_all_buffers);
*/
static void __vb2_dqbuf(struct vb2_buffer *vb)
{
- struct vb2_queue *q = vb->vb2_queue;
- unsigned int i;
-
/* nothing to do if the buffer is already dequeued */
if (vb->state == VB2_BUF_STATE_DEQUEUED)
return;
vb->state = VB2_BUF_STATE_DEQUEUED;
-
- /* unmap DMABUF buffer */
- if (q->memory == VB2_MEMORY_DMABUF)
- for (i = 0; i < vb->num_planes; ++i) {
- if (!vb->planes[i].dbuf_mapped)
- continue;
- call_void_memop(vb, unmap_dmabuf, vb->planes[i].mem_priv);
- vb->planes[i].dbuf_mapped = 0;
- }
}
/**
@@ -1861,6 +1868,9 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
call_void_vb_qop(vb, buf_finish, vb);
}
__vb2_dqbuf(vb);
+
+ if (q->memory == VB2_MEMORY_DMABUF)
+ __vb2_unmap_dmabuf(vb);
}
}
--
2.5.5
--
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