Em Wed, 15 Nov 2017 15:10:49 -0200
Gustavo Padovan <gustavo@xxxxxxxxxxx> escreveu:
> From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
>
> We use ordered_in_driver property to optimize for the case where
> the driver can deliver the buffers in an ordered fashion. When it
> is ordered we can use the same fence context for all fences, but
> when it is not we need to a new context for each out-fence.
>
> So the ordered_in_driver flag will help us with identifying the queues
> that can be optimized and use the same fence context.
>
> v4: make the property a vector for optimization and not a mandatory thing
> that drivers need to set if they want to use explicit synchronization.
>
> v3: improve doc (Hans Verkuil)
>
> v2: rename property to 'ordered_in_driver' to avoid confusion
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
> ---
> include/media/videobuf2-core.h | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index ef9b64398c8c..38b9c8dd42c6 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -440,6 +440,12 @@ struct vb2_buf_ops {
> * @fileio_read_once: report EOF after reading the first buffer
> * @fileio_write_immediately: queue buffer after each write() call
> * @allow_zero_bytesused: allow bytesused == 0 to be passed to the driver
> + * @ordered_in_driver: if the driver can guarantee that the queue will be
> + * ordered or not, i.e., the buffers are dequeued from the driver
> + * in the same order they are queued to the driver. The default
> + * is not ordered unless the driver sets this flag. Setting it
> + * when ordering can be guaranted helps to optimize explicit
> + * fences.
> * @quirk_poll_must_check_waiting_for_buffers: Return POLLERR at poll when QBUF
> * has not been called. This is a vb1 idiom that has been adopted
> * also by vb2.
> @@ -510,6 +516,7 @@ struct vb2_queue {
> unsigned fileio_read_once:1;
> unsigned fileio_write_immediately:1;
> unsigned allow_zero_bytesused:1;
> + unsigned ordered_in_driver:1;
As this may depend on the format, it is probably a good idea to set
this flag either via a function argument or by a function that
would be meant to update it, as video format changes.
> unsigned quirk_poll_must_check_waiting_for_buffers:1;
>
> struct mutex *lock;
--
Thanks,
Mauro
