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

[Jacek Anaszewski]

Hi Vesa,

On 1/5/19 1:39 AM, Vesa JÃÃskelÃinen 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> {
>  ÂÂÂÂcompatible = "lp5024";
>
>  ÂÂÂÂ// There is in hardware setup to use either linear or
>  ÂÂÂÂ// logarithmic scaling:
>  ÂÂÂÂ//enable-logarithmic-brightness;
>
>  ÂÂÂÂled0 {
>  ÂÂÂÂÂÂÂ // this will create led instance for LED0 in lp5024
>  ÂÂÂÂÂÂÂ label = "lp-led0";
>
>  ÂÂÂÂÂÂÂ // This specifies LED number within lp5024
>  ÂÂÂÂÂÂÂ led-index = <0>;ÂÂ // set output-base as 0*3 == 0
>
>  ÂÂÂÂÂÂÂ element-red {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT0
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <0>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂÂÂÂ element-green {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT1
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <1>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂÂÂÂ element-blue {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT2
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <2>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂ};
>
>  ÂÂÂÂled1 {
>  ÂÂÂÂÂÂÂ // this will create led instance for LED1 in lp5024
>  ÂÂÂÂÂÂÂ label = "lp-led1";
>
>  ÂÂÂÂÂÂÂ // This specifies LED number within lp5024
>  ÂÂÂÂÂÂÂ led-index = <1>;ÂÂ // set output-base as 1*3 == 3
>
>  ÂÂÂÂÂÂÂ element-red {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT3
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <0>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂÂÂÂ element-green {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT4
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <1>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂÂÂÂ element-blue {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT5
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <2>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂ};
>
>  ÂÂÂÂbank-led {
>  ÂÂÂÂÂÂÂ // this will create led instance for bank leds in lp5024
>  ÂÂÂÂÂÂÂ label = "lp-bank-led";
>
>  ÂÂÂÂÂÂÂ // configured bank led configuration
>  ÂÂÂÂÂÂÂ led-index = <2 3 4 5 6 7>;
>  ÂÂÂÂÂÂÂ // As here is list of led-indices this entry is
>  ÂÂÂÂÂÂÂ // assumed to be bank configuration. Bank mode is enable
>  ÂÂÂÂÂÂÂ // for the indices.
>
>  ÂÂÂÂÂÂÂ // set output-base as BANK A
>
>  ÂÂÂÂÂÂÂ element-red {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to BANK A
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <0>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂÂÂÂ element-green {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to BANK B
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <1>;
>  ÂÂÂÂÂÂÂ };
>
>  ÂÂÂÂÂÂÂ element-blue {
>  ÂÂÂÂÂÂÂÂÂÂÂ // refers to BANK C
>  ÂÂÂÂÂÂÂÂÂÂÂ output-offset = <2>;
>  ÂÂÂÂÂÂÂ };
>  ÂÂÂÂ};
> };
>
> This would then create three led instances and each led instance has 
> brightness setting and that goes straight to hardware.
>
> If one would want to override hardware control for brightness then I 
> suppose you would define in led node something like:
>
>  ÂÂÂÂbrightness-model = "hsl"
>
> This would then pick red, green and blue elements for hsl calculations 
> and others color elements for linear. LED specific hardware brightness 
> would then be either 0 or 0xFF depending if all of LED color elements 
> are zero or not.
>
> Would that kind of model work?

I'd prefer to have single RGB LED device. And your DT design
is unnecessarily complex and a bit confusing.

Also, you provided scarce information about sysfs interface.
It would be nice to see the sequence of commands.

--
Best regards,
Jacek Anaszewski