Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Subject: Re: [PATCH v8 12/13] [media] v4l: Add V4L2_CAP_FENCES to drivers
To:     Gustavo Padovan <gustavo@padovan.org>, linux-media@vger.kernel.org
Cc:     kernel@collabora.com,
        Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
        Shuah Khan <shuahkh@osg.samsung.com>,
        Pawel Osciak <pawel@osciak.com>,
        Alexandre Courbot <acourbot@chromium.org>,
        Sakari Ailus <sakari.ailus@iki.fi>,
        Brian Starkey <brian.starkey@arm.com>,
        linux-kernel@vger.kernel.org,
        Gustavo Padovan <gustavo.padovan@collabora.com>
References: <20180309174920.22373-1-gustavo@padovan.org>
 <20180309174920.22373-13-gustavo@padovan.org>
From:   Hans Verkuil <hverkuil@xs4all.nl>
Message-ID: <77c125e0-8f3f-07fd-ac80-0d8491597c18@xs4all.nl>
Date:   Wed, 14 Mar 2018 09:07:52 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.3.0
MIME-Version: 1.0
In-Reply-To: <20180309174920.22373-13-gustavo@padovan.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 03/09/2018 09:49 AM, Gustavo Padovan wrote:
> From: Gustavo Padovan <gustavo.padovan@collabora.com>
> 
> Drivers that use videobuf2 are capable of using fences and
> should report that to userspace.
> 
> The coding style is following what each drivers was already
> doing.

I think this can be simplified for most drivers: you can set this
flag in the v4l_querycap function if vdev->queue is not NULL or if
m2m_ctx is set in struct v4l2_fh.

I believe all non-m2m drivers that use vb2 set vdev->queue. But not
all m2m drivers will set m2m_ctx, so that will need to be checked.

In other words, this way you only need to modify m2m drivers that
do not set m2m_ctx.

Regards,

	Hans