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Date:   Tue, 6 Jun 2023 13:36:18 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Michael Riesch <michael.riesch@wolfvision.net>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        libcamera-devel@lists.libcamera.org,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Matthias Fend <Matthias.Fend@wolfvision.net>,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC v2 2/6] media: v4l2-ctrls: clarify documentation of
 V4L2_CID_FOCUS_RELATIVE
Message-ID: <20230606103618.GB25774@pendragon.ideasonboard.com>
References: <20230406-feature-controls-lens-v2-0-faa8ad2bc404@wolfvision.net>
 <20230406-feature-controls-lens-v2-2-faa8ad2bc404@wolfvision.net>
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In-Reply-To: <20230406-feature-controls-lens-v2-2-faa8ad2bc404@wolfvision.net>
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Hi Michael,

Thank you for the patch.

On Tue, Apr 25, 2023 at 11:45:12AM +0200, Michael Riesch wrote:
> The control V4L2_CID_FOCUS_RELATIVE only makes sense if the device cannot
> handle absolute focal point positioning with V4L2_CID_FOCUS_ABSOLUTE.
> Clarify this in the documentation.
> 
> Signed-off-by: Michael Riesch <michael.riesch@wolfvision.net>
> ---
>  Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst
> index df29150dce7b..42cf4c3cda0c 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-camera.rst
> @@ -147,7 +147,9 @@ enum v4l2_exposure_metering -
>      This control moves the focal point of the camera by the specified
>      amount. The unit is undefined. Positive values move the focus closer
>      to the camera, negative values towards infinity. This is a
> -    write-only control.
> +    write-only control. It should be implemented only if the device cannot
> +    handle absolute values.
> +

Extra blank line.

I don't think this is right. The control was added for the UVC driver,
and there are devices that implement both absolute and relative focus.

>  
>  ``V4L2_CID_FOCUS_AUTO (boolean)``
>      Enables continuous automatic focus adjustments. The effect of manual
> 

-- 
Regards,

Laurent Pinchart