linux-kernel - Re: [libcamera-devel] [PATCH RFC 1/4] media: v4l2-ctrls: add lens group status controls for zoom and focus

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Date:   Wed, 12 Apr 2023 18:12:19 +0300
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Dave Stevenson <dave.stevenson@...pberrypi.com>
Cc:     Michael Riesch <michael.riesch@...fvision.net>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Michael Riesch via B4 Relay 
        <devnull+michael.riesch.wolfvision.net@...nel.org>,
        linux-kernel@...r.kernel.org,
        Matthias Fend <Matthias.Fend@...fvision.net>,
        libcamera-devel@...ts.libcamera.org, linux-media@...r.kernel.org
Subject: Re: [libcamera-devel] [PATCH RFC 1/4] media: v4l2-ctrls: add lens
 group status controls for zoom and focus

Hi Dave, Michael,

On Wed, Apr 12, 2023 at 02:55:56PM +0100, Dave Stevenson wrote:
> > > If the ranges aren't updated, where should that out-of-range lens
> > > movement leave the lens?
> >
> > This is up to the hardware controller, but I would guess it typically
> > stops one step before disaster. Wherever that may be, the error
> > condition and the current position can be read out via this new STATUS
> > control.
> >
> > Does this sound good so far?
> 
> Sounds reasonable, but I'm not the gatekeeper (that would be Sakari or
> Laurent), and I'm just expressing my views based on the lenses I've
> encountered.
> All of my lenses have a single drive for focus, a single drive for
> zoom, and where there are multiple elements they are all connected
> mechanically. Your setup sounds far more complex and is likely to need
> a more extensive driver, but it'd be nice to not unnecessarily
> overcomplicate the interface.

Could we also have a driver that uses these new controls?

The controls themselves appear reasonable to me as well. I guess there are
changes to be made based on the discussion?

-- 
Regards,

Sakari Ailus