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Message-ID: <77d91964-de0a-8bd4-12d9-bc16110cfa7c@wolfvision.net>
Date:   Wed, 12 Apr 2023 15:43:26 +0200
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Subject: Re: [libcamera-devel] [PATCH RFC 1/4] media: v4l2-ctrls: add lens
 group status controls for zoom and focus
Content-Language: en-US
To:     Sakari Ailus <sakari.ailus@linux.intel.com>
Cc:     Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Michael Riesch via B4 Relay 
        <devnull+michael.riesch.wolfvision.net@kernel.org>,
        linux-kernel@vger.kernel.org,
        Matthias Fend <Matthias.Fend@wolfvision.net>,
        libcamera-devel@lists.libcamera.org, linux-media@vger.kernel.org,
        hverkuil@xs4all.nl
References: <20230406-feature-controls-lens-v1-0-543189a680de@wolfvision.net>
 <20230406-feature-controls-lens-v1-1-543189a680de@wolfvision.net>
 <CAPY8ntArOOqPQzvkJrQEyuVFfb6j8x6WODTMHOn1qHPU588mbQ@mail.gmail.com>
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 <CAPY8ntAjBEFfeV6nnQs34Y22QM-irT13ALDv4ksP8AYK=jWsKg@mail.gmail.com>
 <3ab7bfc4-aaae-2e39-b420-40ad8d71dda4@wolfvision.net>
 <ZDaa+qhoZxZ5ymxL@kekkonen.localdomain>
 <8fe5c9c5-6eb0-86ae-9e5d-fbaa72be25fe@wolfvision.net>
 <ZDaemghP0HQSw3Fo@kekkonen.localdomain>
From:   Michael Riesch <michael.riesch@wolfvision.net>
Organization: WolfVision GmbH
In-Reply-To: <ZDaemghP0HQSw3Fo@kekkonen.localdomain>
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Hi Sakari,

On 4/12/23 14:05, Sakari Ailus wrote:
> Hi Michael,
> 
> On Wed, Apr 12, 2023 at 01:57:36PM +0200, Michael Riesch wrote:
>> Hi Sakari,
>>
>> On 4/12/23 13:50, Sakari Ailus wrote:
>>> Hi Michael,
>>>
>>> On Wed, Apr 12, 2023 at 10:00:26AM +0200, Michael Riesch wrote:
>>>>  - Different controls: If moving = (V4L2_CID_FOCUS_ABSOLUTE == current),
>>>>    then what happens if the application performs a
>>>>    V4L2_CID_FOCUS_RELATIVE with -3? current should reach 39,
>>>>    V4L2_CID_FOCUS_ABSOLUTE is still at 42, the lens is still moving from
>>>>    the application's point of view.
>>>
>>> Would there be a reason to implement both of these controls in a single
>>> driver? AFAIU, the relative one should be used if there absolute value
>>> isn't known to the driver.
>>
>> Probably not, but on the other hand there is nothing the prevents a
>> driver developer from doing so, right? Point is that should there be a
>> driver which does implement both controls, we are in trouble AFAIU.
> 
> I think the documentation should be improved in this regard.

The documentation of which control exactly? And what items should be added?

Thanks for the pointers!

Best regards,
Michael

> 
> Also cc Hans.
>