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

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Date:	Wed, 10 Dec 2014 13:41:21 +0100
From:	Jacek Anaszewski <j.anaszewski@...sung.com>
To:	Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc:	Pavel Machek <pavel@....cz>, 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

On 12/10/2014 01:20 PM, Sylwester Nawrocki wrote:
> 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".

For me this sounds reasonable. Moreover we will avoid the need for
address-cells and size-cells properties in the parent node.

Best Regards,
Jacek Anaszewski
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