On 06/16/17 09:39, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
>
> For explicit synchronization (and soon for HAL3/Request API) we need
> the v4l2-driver to guarantee the ordering which the buffer were queued
> by userspace. This is already true for many drivers, but we never had
> the need to say it.
>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxx>
> ---
> include/media/videobuf2-core.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index aa43e43..a8b800e 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -491,6 +491,9 @@ struct vb2_buf_ops {
> * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
> * last decoded buffer was already dequeued. Set for capture queues
> * when a buffer with the V4L2_BUF_FLAG_LAST is dequeued.
> + * @ordered: if the driver can guarantee that the queue will be ordered or not.
> + * The default is not ordered unless the driver sets this flag. It
> + * is mandatory for using explicit fences.
This needs to be clarified both here and in the commit log.
1) what is meant with 'ordered'? I assume FIFO is meant.
2) is it the order in which buffers are queued in the driver, or the order
in which buffers are queued in userspace? With in-fences it is ordered
in the driver but not in userspace since the in-fence will block a buffer
from being queued to the driver until the fence callback is called.
3) does this apply to in-fences or out-fences or both? It appears that this
only applies to out-fences.
> * @fileio: file io emulator internal data, used only if emulator is active
> * @threadio: thread io internal data, used only if thread is active
> */
> @@ -541,6 +544,7 @@ struct vb2_queue {
> unsigned int is_output:1;
> unsigned int copy_timestamp:1;
> unsigned int last_buffer_dequeued:1;
> + unsigned int ordered:1;
>
> struct vb2_fileio_data *fileio;
> struct vb2_threadio_data *threadio;
>
Regards,
Hans
