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Date:   Mon, 2 Sep 2019 11:00:02 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Jacopo Mondi <jacopo@jmondi.org>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        "open list:MEDIA INPUT INFRASTRUCTURE (V4L/DVB)" 
        <linux-media@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [RFC 2/5] media: v4l2-ctrl: Document V4L2_CID_LOCATION
Message-ID: <20190902080002.GC4777@pendragon.ideasonboard.com>
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 <20190901172457.GC1047@bug>
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Hi Pavel,

On Sun, Sep 01, 2019 at 07:24:57PM +0200, Pavel Machek wrote:
> >>>>>> @@ -510,6 +510,29 @@ enum v4l2_scene_mode -
> >>>>>>      value down. A value of zero stops the motion if one is in progress
> >>>>>>      and has no effect otherwise.
> >>>>>>
> >>>>>> +``V4L2_CID_LOCATION (integer)``
> >>>>>
> >>>>> Maybe V4L2_CID_CAMERA_SENSOR_LOCATION ? Same for the values below.
> >>>>
> >>>> Probably a better name, if a bit long. But we might need other location
> >>>> controls in the future (e.g. flash location), so CID_LOCATION is just too
> >>>> generic.
> >>>
> >> 
> >> Thanks for the feedback.
> >> 
> >>> Note that the location defines themselves can most likely be used with any
> >>> LOCATION control, so V4L2_LOCATION_FRONT would be fine with any control.
> >>>
> >> 
> >> What do you think instead of the control type? Would a single integer
> >> control do or an integer menu one would be better? I see merit in both
> >> proposals actually...
> > 
> > Single integer. It's read-only, so it just reports the location.
> > 
> > It would be different if this was a writable control: then you need to
> > know which locations are possible to set, and that requires a menu type.
> > 
> > But it doesn't make sense to set the location from software. However, the
> > location might change as a result of other changes: e.g. if the camera
> > has motor control of the tilt and the tilt changes from forward facing to
> > downward facing, then the driver might change the location from FRONT
> > to DOWN. A convoluted example perhaps, but this is just brainstorming.
> 
> There are phones with exactly such camera setup. And yes, it makes
> sense to be writable in that case, as software can move the camera in
> such case.

Out of curiosity, what phones are those ?

-- 
Regards,

Laurent Pinchart