On 07/03/2015 12:20 PM, Sakari Ailus wrote:
> Buffers can be returned back to videobuf2 in driver's streamon handler. In
> this case vb2_buffer_done() with buffer state VB2_BUF_STATE_QUEUED will
> cause the driver's buf_queue vb2 operation to be called, queueing the same
> buffer again only to be returned to videobuf2 using vb2_buffer_done() and so
> on.
>
> Instead of using q->start_streamin_called to judge whether to return the
> buffer to the driver immediately, use q->streaming which is set only after
> the driver's start_streaming() vb2 operation is called.
I don't think this patch will work. If q->min_buffers_needed is > 0, then
q->streaming and q->start_streaming_called will both be true in
vb2_buffer_done(),
still causing the same issue.
The problem is that there is no clear distinction between STATE_QUEUED as used
in start_streaming and STATE_QUEUED as used to requeue a buffer while streaming.
The best option here I think is to introduce a STATE_REQUEUE for the second use
case.
Regards,
Hans
>
> Fixes: ce0eff016f72 ("[media] vb2: allow requeuing buffers while streaming")
> Signed-off-by: Sakari Ailus <sakari.ai...@linux.intel.com>
> Cc: sta...@vger.kernel.org # for v4.1
> ---
> drivers/media/v4l2-core/videobuf2-core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c
> b/drivers/media/v4l2-core/videobuf2-core.c
> index 1a096a6..6957078 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1208,7 +1208,7 @@ void vb2_buffer_done(struct vb2_buffer *vb, enum
> vb2_buffer_state state)
> spin_unlock_irqrestore(&q->done_lock, flags);
>
> if (state == VB2_BUF_STATE_QUEUED) {
> - if (q->start_streaming_called)
> + if (q->streaming)
> __enqueue_in_driver(vb);
> return;
> }
>
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