On 06/04/14 16:05, Laurent Pinchart wrote:
> The V4L2 specification states that
>
> "When the application did not call VIDIOC_QBUF or VIDIOC_STREAMON yet
> the poll() function succeeds, but sets the POLLERR flag in the revents
> field."
>
> The vb2_poll() function sets POLLERR when the queued buffers list is
> empty, regardless of whether this is caused by the stream not being
> active yet, or by a transient buffer underrun.
>
> Bring the implementation in line with the specification by returning
> POLLERR only when the queue is not streaming. Buffer underruns during
> streaming are not treated specially anymore and just result in poll()
> blocking until the next event.
>
> Signed-off-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verk...@cisco.com>
Regards,
Hans
> ---
> drivers/media/video/videobuf2-core.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/media/video/videobuf2-core.c
> b/drivers/media/video/videobuf2-core.c
> index 11d31bf..5f38774 100644
> --- a/drivers/media/video/videobuf2-core.c
> +++ b/drivers/media/video/videobuf2-core.c
> @@ -1984,9 +1984,9 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file
> *file, poll_table *wait)
> }
>
> /*
> - * There is nothing to wait for if no buffers have already been queued.
> + * There is nothing to wait for if the queue isn't streaming.
> */
> - if (list_empty(&q->queued_list))
> + if (!vb2_is_streaming(q))
> return res | POLLERR;
>
> poll_wait(file, &q->done_wq, wait);
>
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