linux-kernel - Re: [PATCH v2 1/2] dt: bindings: lm3697: Add bindings for lm3697 driver

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Message-ID: <20180809132418.GB4469@localhost>
Date:   Thu, 9 Aug 2018 15:24:18 +0200
From:   Pavel Machek <pavel@....cz>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>
Cc:     Dan Murphy <dmurphy@...com>, robh+dt@...nel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-leds@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dt: bindings: lm3697: Add bindings for lm3697
 driver

Hi!

> >>> 2 sinks 3 LED strings.  How do you know which LED string is which and what bank it belongs
> >>> to when setting the brightness.  Each Bank has a separate register for brightness control.
> >>
> >> Just a blind shot, without going into details - could you please check
> >> if led-sources property documented in the common LED bindings couldn't
> >> help here?
> >>
> > 
> > I could change the name to led-sources.  But this part does not really follow the 1 output to a
> > 1 LED string topology.
> 
> led-sources was designed for describing the topology where one LED can
> be connected to more then one output, see bindings of
> max77693-led (in Documentation/devicetree/bindings/mfd/max77693.txt).
> 
> Here the topology is a bit different - more than one LED (string) can be
> connected to a single bank, but this is accomplished inside the chip.
> Logically LEDs configured that way can be treated as a single LED
> (string) connected to two outputs, and what follows they should be
> described by a single DT child node.
> 
> led-sources will fit very well for this purpose. You could do
> the following mapping:
> 
> 0 - HVLED1
> 1 - HVLED2
> 2 - HVLED3
> 
> Then, in the child DT nodes you would use these identifiers to describe
> the topology:
> 
> Following node would describe strings connected to the outputs
> HVLED1 and HVLED2 controlled by bank A.
> 
> led@0 {
> 	reg = <0>;
> 	led-sources = <0>. <1>;
> 	label = "white:first_backlight_cluster";
> 	linux,default-trigger = "backlight";
> };
> 
> 
> IOW I agree with Pavel, but I propose to use already documented common
> DT LED property.

This is better than my proposal. Thanks!
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html