Re: [PATCH] vb2: fix vb2_poll for output streams

[Marek Szyprowski <m.szyprowski@samsung.com>]

Hello,

On 2014-07-24 14:19, Hans Verkuil wrote:
> vb2_poll should always return POLLOUT | POLLWRNORM as long as there
> are fewer buffers queued than there are buffers available. Poll for
> an output stream should only wait if all buffers are queued and nobody
> is dequeuing them.
>
> Signed-off-by: Hans Verkuil <hansverk@cisco.com>

Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>   drivers/media/v4l2-core/videobuf2-core.c | 7 +++++++
>   1 file changed, 7 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index f33508f..c359006 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -2596,6 +2596,13 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
>   	if ((list_empty(&q->queued_list) && !vb2_is_streaming(q)) || q->error)
>   		return res | POLLERR;
>   
> +	/*
> +	 * For output streams you can write as long as there are fewer buffers
> +	 * queued than there are buffers available.
> +	 */
> +	if (V4L2_TYPE_IS_OUTPUT(q->type) && q->queued_count < q->num_buffers)
> +		return res | POLLOUT | POLLWRNORM;
> +
>   	if (list_empty(&q->done_list))
>   		poll_wait(file, &q->done_wq, wait);
>   

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland