On (21/09/10 22:31), Sergey Senozhatsky wrote:
> > Looking into it now. I ran v4l2-compliance, but not "contrib/test/test-media"
>
> AFAICT the problem is in v4l2-compliance patch.
>
> We clear request flags if queue does not support user-space cache hints:
>
> q->allow_cache_hints && q->memory == VB2_MEMORY_MMAP
>
> But for DMABUF buffers (only) we set cache hints internally in
> set_buffer_cache_hints() and always skip cache sync/flush on
> prepare/finish regardless of what is passed from the user-space:
>
> if (q->memory == VB2_MEMORY_DMABUF) {
> vb->skip_cache_sync_on_finish = 1;
> vb->skip_cache_sync_on_prepare = 1;
> return;
> }
>
> Technically we don't support user-space cache hints for DMABUF, so we
> clear passed user-space cache hint flags.
>
> I think the fix should look like this (tested with "test-media vivid"):
>
> ---
>
> diff --git a/utils/v4l2-compliance/v4l2-test-buffers.cpp b/utils/v4l2-compliance/v4l2-test-buffers.cpp
> index 9b87c90f..baa306f1 100644
> --- a/utils/v4l2-compliance/v4l2-test-buffers.cpp
> +++ b/utils/v4l2-compliance/v4l2-test-buffers.cpp
> @@ -1865,9 +1865,10 @@ static int setupDmaBuf(struct node *expbuf_node, struct node *node,
> fail_on_test(!buf.g_bytesused(p));
> }
> flags = buf.g_flags();
> - /* We always skip cache sync/flush for DMABUF memory type */
> - fail_on_test(!(flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE));
> - fail_on_test(!(flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN));
> +
> + /* Make sure that flags are cleared */
> + fail_on_test((flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE));
> + fail_on_test((flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN));
> fail_on_test(flags & V4L2_BUF_FLAG_DONE);
> fail_on_test(buf.querybuf(node, i));
> fail_on_test(buf.check(q, Queued, i));
Alternatively, we can do something like below on the kernel side instead:
do nothing in v4l2 for DMABUF and preserve b->flags (if user-space has
passed cache management flags).
// But I think it'll be better to clear b->flags cache hints for DMABUF. To
// indicate that we don't accept cache-hints for DMABUF.
---
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 6edf4508c636..fc8e31b7dced 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -345,6 +345,13 @@ static void set_buffer_cache_hints(struct vb2_queue *q,
struct vb2_buffer *vb,
struct v4l2_buffer *b)
{
+ /*
+ * No user-space cache hints for DMABUF, but we preserve b->flags
+ * cache hints (if user-space has passed any).
+ */
+ if (q->memory == VB2_MEMORY_DMABUF)
+ return;
+
if (!vb2_queue_allows_cache_hints(q)) {
/*
* Clear buffer cache flags if queue does not support user
