Re: [PATCH v9 05/15] vb2: add unordered vb2_queue property for drivers

Hans Verkuil
2018-05-07T11:03:20Z

On 04/05/18 22:06, Ezequiel Garcia wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.com>
>
> Explicit synchronization benefits a lot from ordered queues, they fit
> better in a pipeline with DRM for example so create a opt-in way for
> drivers notify videobuf2 that the queue is unordered.
>
> v5: go back to a bitfield property for the unordered property.

This needs to be a callback. Whether or not the queue is unordered depends
on the current format (see the next two patches). So if a queue can e.g.
capture both raw/MJPEG and compressed (MPEG-like) data, then it has to call
a callback.

Regards,

Hans

>
> v4: rename it to vb2_ops_is_unordered() (Hans Verkuil)
>
> v3: - make it bool (Hans)
> - create vb2_ops_set_unordered() helper
>
> v2: improve comments for is_unordered flag (Hans Verkuil)
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
> Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
> ---
> include/media/videobuf2-core.h | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index f9633de0386c..364e4cb41b10 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -467,6 +467,8 @@ struct vb2_buf_ops {
> * @quirk_poll_must_check_waiting_for_buffers: Return %EPOLLERR at poll when QBUF
> * has not been called. This is a vb1 idiom that has been adopted
> * also by vb2.
> + * @unordered: tell if the queue is unordered, i.e. buffers can be
> + * dequeued in a different order from how they were queued.
> * @lock: pointer to a mutex that protects the &struct vb2_queue. The
> * driver can set this to a mutex to let the v4l2 core serialize
> * the queuing ioctls. If the driver wants to handle locking
> @@ -533,6 +535,7 @@ struct vb2_queue {
> unsigned fileio_read_once:1;
> unsigned fileio_write_immediately:1;
> unsigned allow_zero_bytesused:1;
> + unsigned unordered:1;
> unsigned quirk_poll_must_check_waiting_for_buffers:1;
>
> struct mutex *lock;
>