linux-kernel - Re: [PATCH 2/2] leds: lp5024: Add the LP5024/18 RGB LED driver

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Date:   Wed, 9 Jan 2019 08:20:04 +0200
From:   Vesa Jääskeläinen <dachaac@...il.com>
To:     Dan Murphy <dmurphy@...com>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>
Cc:     robh+dt@...nel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH 2/2] leds: lp5024: Add the LP5024/18 RGB LED driver

Hi Dan,

On 07/01/2019 21.34, Dan Murphy wrote:
> Vesa
> 
> On 1/4/19 6:39 PM, Vesa Jääskeläinen wrote:
>> Hi Jacek,
>>
>> On 04/01/2019 23.37, Jacek Anaszewski wrote:
>>> But, aside from that hypothetic issue, we need a solution for
>>> LEDn_BRIGHTNESS feature of lp5024, i.e. setting color intensity
>>> via a single register write. How would you propose to address that?
>>
>> You could model it to something like this in device tree:
>>
>> led-module @ <i2c-address> {
>>      compatible = "lp5024";
>>
>>      // There is in hardware setup to use either linear or
>>      // logarithmic scaling:
>>      //enable-logarithmic-brightness;
>>
>>      led0 {
>>          // this will create led instance for LED0 in lp5024
>>          label = "lp-led0";
>>         
>>          // This specifies LED number within lp5024
>>          led-index = <0>;   // set output-base as 0*3 == 0
>>         
>>          element-red {
>>              // refers to OUT0
>>              output-offset = <0>;
>>          };
>>         
>>          element-green {
>>              // refers to OUT1
>>              output-offset = <1>;
>>          };
>>         
>>          element-blue {
>>              // refers to OUT2
>>              output-offset = <2>;
>>          };
>>         
>>      };
>>
>>      led1 {
>>          // this will create led instance for LED1 in lp5024
>>          label = "lp-led1";
>>         
>>          // This specifies LED number within lp5024
>>          led-index = <1>;   // set output-base as 1*3 == 3
>>
> 
> Can we not use led-sources like I have done already?

It was just for illustration of the idea. Names can be agreed. I have 
nothing against led-sources name. I was just looking at datasheet to try 
to undestand what it did and then tried to figure out if it could be 
mapped the idea I have been playing with.

> I really like to keep the DT nodes simple and re-use nodes that exist if possible.

I'll reply to Jacek's email about more clarifications of the idea.

Thanks,
Vesa Jääskeläinen

> My code already maps and groups the outputs into the associated banks