linux-kernel - Re: [PATCH v6 1/6] [media] vb2: add is

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Date:   Thu, 21 Dec 2017 16:51:28 -0200
From:   Mauro Carvalho Chehab <mchehab@....samsung.com>
To:     Gustavo Padovan <gustavo@...ovan.org>
Cc:     linux-media@...r.kernel.org, Hans Verkuil <hverkuil@...all.nl>,
        Shuah Khan <shuahkh@....samsung.com>,
        Pawel Osciak <pawel@...iak.com>,
        Alexandre Courbot <acourbot@...omium.org>,
        Sakari Ailus <sakari.ailus@....fi>,
        Brian Starkey <brian.starkey@....com>,
        Thierry Escande <thierry.escande@...labora.com>,
        linux-kernel@...r.kernel.org,
        Gustavo Padovan <gustavo.padovan@...labora.com>
Subject: Re: [PATCH v6 1/6] [media] vb2: add is_unordered callback for
 drivers

Em Mon, 11 Dec 2017 16:27:36 -0200
Gustavo Padovan <gustavo@...ovan.org> escreveu:

> From: Gustavo Padovan <gustavo.padovan@...labora.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.
> 
> Drivers don't need implement it if the queue is ordered.
> 
> Signed-off-by: Gustavo Padovan <gustavo.padovan@...labora.com>
> ---
>  include/media/videobuf2-core.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index ef9b64398c8c..eddb38a2a2f3 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -368,6 +368,9 @@ struct vb2_buffer {
>   *			callback by calling vb2_buffer_done() with either
>   *			%VB2_BUF_STATE_DONE or %VB2_BUF_STATE_ERROR; may use
>   *			vb2_wait_for_all_buffers() function
> + * @is_unordered:	tell if the queue format is unordered. The default is
> + *			assumed to be ordered and this function only needs to
> + *			be implemented for unordered queues.
>   * @buf_queue:		passes buffer vb to the driver; driver may start
>   *			hardware operation on this buffer; driver should give
>   *			the buffer back by calling vb2_buffer_done() function;
> @@ -391,6 +394,7 @@ struct vb2_ops {
>  
>  	int (*start_streaming)(struct vb2_queue *q, unsigned int count);
>  	void (*stop_streaming)(struct vb2_queue *q);
> +	int (*is_unordered)(struct vb2_queue *q);
>  
>  	void (*buf_queue)(struct vb2_buffer *vb);
>  };
> @@ -564,6 +568,7 @@ struct vb2_queue {
>  	u32				cnt_wait_finish;
>  	u32				cnt_start_streaming;
>  	u32				cnt_stop_streaming;
> +	u32				cnt_is_unordered;

If I understand, this is just a bit, right?

if so, better to declare it as:

	u32				cnt_is_unordered : 1;

>  #endif
>  };
>  


-- 
Thanks,
Mauro