linux-kernel - Re: [PATCH/RFC v9 06/19] DT: Add documentation for the mfd Maxim max77693

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Message-id: <54883A70.7070903@samsung.com>
Date:	Wed, 10 Dec 2014 13:20:00 +0100
From:	Sylwester Nawrocki <s.nawrocki@...sung.com>
To:	Pavel Machek <pavel@....cz>,
	Jacek Anaszewski <j.anaszewski@...sung.com>
Cc:	Sakari Ailus <sakari.ailus@....fi>, linux-leds@...r.kernel.org,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	kyungmin.park@...sung.com, b.zolnierkie@...sung.com,
	cooloney@...il.com, rpurdie@...ys.net, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	Andrzej Hajda <a.hajda@...sung.com>,
	Lee Jones <lee.jones@...aro.org>,
	Chanwoo Choi <cw00.choi@...sung.com>,
	devicetree@...r.kernel.org
Subject: Re: [PATCH/RFC v9 06/19] DT: Add documentation for the mfd Maxim
 max77693

Hi,

On 04/12/14 17:12, Pavel Machek wrote:
>>>> +- maxim,boost-mode :
>>>> > >>+	In boost mode the device can produce up to 1.2A of total current
>>>> > >>+	on both outputs. The maximum current on each output is reduced
>>>> > >>+	to 625mA then. If there are two child led nodes defined then boost
>>>> > >>+	is enabled by default.
>>>> > >>+	Possible values:
>>>> > >>+		MAX77693_LED_BOOST_OFF - no boost,
>>>> > >>+		MAX77693_LED_BOOST_ADAPTIVE - adaptive mode,
>>>> > >>+		MAX77693_LED_BOOST_FIXED - fixed mode.
>>>> > >>+- maxim,boost-vout : Output voltage of the boost module in millivolts.
>>>> > >>+- maxim,vsys-min : Low input voltage level in millivolts. Flash is not fired
>>>> > >>+	if chip estimates that system voltage could drop below this level due
>>>> > >>+	to flash power consumption.
>>>> > >>+
>>>> > >>+Required properties of the LED child node:
>>>> > >>+- label : see Documentation/devicetree/bindings/leds/common.txt
>>>> > >>+- maxim,fled_id : Identifier of the fled output the led is connected to;
>>> > >
>>> > >I'm pretty sure this will be needed for about every chip that can drive
>>> > >multiple LEDs. Shouldn't it be documented in the generic documentation?
>> > 
>> > OK.
>
> Well... "fled_id" is not exactly suitable name. On other busses, it
> would be "reg = <1>"?

I think we need to clarify what the LED device node subnodes really mean.
I thought initially they describe a physical current output of the LED
controller, but it turns out the subnode corresponds to a LED attached
to the LED controller.  Since a LED can be connected to multiple outputs
of the LED controller I think 'reg' property doesn't make sense here.

Then presumably we should use a property in each subnode, telling which
LED controller outputs a LED is connected to?

For instance, if we assign numbers 0, 1 to FLED1, FLED2 outputs of
MAX77693 and there is just one LED connected to those outputs we would
have something like:

max77693: led {
	compatible = "maxim,max77693-led";	
	...
	led1 {
		maxim,fled-sources = <0 1>;
		...
	};
};

Feel free to propose better name for the property, I guess we need to
avoid "maxim,current-sources" due to ambiguity of the word "current".

--
Regards,
Sylwester
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