On Mon, Aug 4, 2014 at 2:36 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> Recently WARN_ON() calls have been added to warn if the driver is not
> properly returning buffers to vb2 in start_streaming (if it fails) or
> stop_streaming(). Add comments before those WARN_ON calls that refer
> to the videobuf2-core.h header that explains what drivers are supposed
> to do in these situations. That should help point developers in the
> right direction if they see these warnings.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Pawel Osciak <pawel@xxxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-core.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index c359006..d3f2a22 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1762,6 +1762,12 @@ static int vb2_start_streaming(struct vb2_queue *q)
> q->start_streaming_called = 0;
>
> dprintk(1, "driver refused to start streaming\n");
> + /*
> + * If you see this warning, then the driver isn't cleaning up properly
> + * after a failed start_streaming(). See the start_streaming()
> + * documentation in videobuf2-core.h for more information how buffers
> + * should be returned to vb2 in start_streaming().
> + */
> if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
> unsigned i;
>
> @@ -2123,6 +2129,12 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
> if (q->start_streaming_called)
> call_void_qop(q, stop_streaming, q);
>
> + /*
> + * If you see this warning, then the driver isn't cleaning up properly
> + * in stop_streaming(). See the stop_streaming() documentation in
> + * videobuf2-core.h for more information how buffers should be returned
> + * to vb2 in stop_streaming().
> + */
> if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
> for (i = 0; i < q->num_buffers; ++i)
> if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
> --
> 2.0.1
>
--
Best regards,
Pawel Osciak
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