linux-kernel - Re: [PATCHv5] support for AD5820 camera auto-focus coil

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Message-ID: <20160602192737.GA7984@amd>
Date:	Thu, 2 Jun 2016 21:27:37 +0200
From:	Pavel Machek <pavel@....cz>
To:	Sakari Ailus <sakari.ailus@....fi>
Cc:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
	pali.rohar@...il.com, sre@...nel.org,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-omap@...r.kernel.org, tony@...mide.com, khilman@...nel.org,
	aaro.koskinen@....fi, patrikbachan@...il.com, serge@...lyn.com,
	linux-media@...r.kernel.org, mchehab@....samsung.com
Subject: Re: [PATCHv5] support for AD5820 camera auto-focus coil

On Thu 2016-06-02 10:45:45, Sakari Ailus wrote:
> On Thu, Jun 02, 2016 at 12:08:40AM +0200, Pavel Machek wrote:
> > On Wed 2016-06-01 18:24:39, Sakari Ailus wrote:
> > > Hi Pavel,
> > 
> > > > Well, it does not use any dt properties. So there's not really much to
> > > > discuss with dt people...
> > > > 
> > > > Maybe "ad5820" needs to go to list of simple i2c drivers somewhere,
> > > > but...
> > > 
> > > It's an I2C device and it does use a regulator. Not a lot, though, these are
> > > both quite basic stuff. This should still be documented as the people who
> > > write the DT bindings (in general) aren't expected to read driver code as
> > > well. That's at least my understanding.
> > 
> > Yep, you are right, I forgot about the regulator. Something like this?
> > 
> > Thanks,
> > 									Pavel
> > 
> > diff --git a/Documentation/devicetree/bindings/media/i2c/ad5820.txt b/Documentation/devicetree/bindings/media/i2c/ad5820.txt
> > new file mode 100644
> > index 0000000..87c98f1
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/media/i2c/ad5820.txt
> 
> I might use the compatible string as such as a part of the file name. Up to
> you.

Sorry, can't do that, for consistency with other ad* files in the directory.

> > @@ -0,0 +1,20 @@
> > +* Analog Devices AD5820 autofocus coil
> > +
> > +Required Properties:
> > +
> > +  - compatible: Must contain "adi,ad5820"
> > +
> > +  - reg: I2C slave address
> > +
> > +  - VANA-supply: supply of voltage for VANA pin
> > +
> > +Example:
> > +
> > +       /* D/A converter for auto-focus */
> 
> There is definitely D/A conversion happening there but I'm not sure I'd
> characterise the device as such. They're typically called "voice coil
> drivers", perhaps because the devices are similar to a parts of a
> loudspeaker.

Well, I'm pretty sure I did not invent that comment, but I can drop
it.

Best regards,
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html