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

[Dan Murphy]

Jacek

On 1/7/19 3:13 PM, Jacek Anaszewski wrote:
> 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> {
>> ÂÂÂÂÂcompatible = "lp5024";
>>
>> ÂÂÂÂÂ// There is in hardware setup to use either linear or
>> ÂÂÂÂÂ// logarithmic scaling:
>> ÂÂÂÂÂ//enable-logarithmic-brightness;
>>
>> ÂÂÂÂÂled0 {
>> ÂÂÂÂÂÂÂÂ // this will create led instance for LED0 in lp5024
>> ÂÂÂÂÂÂÂÂ label = "lp-led0";
>>
>> ÂÂÂÂÂÂÂÂ // This specifies LED number within lp5024
>> ÂÂÂÂÂÂÂÂ led-index = <0>;ÂÂ // set output-base as 0*3 == 0
>>
>> ÂÂÂÂÂÂÂÂ element-red {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT0
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <0>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂÂÂÂ element-green {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT1
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <1>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂÂÂÂ element-blue {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT2
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <2>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂ};
>>
>> ÂÂÂÂÂled1 {
>> ÂÂÂÂÂÂÂÂ // this will create led instance for LED1 in lp5024
>> ÂÂÂÂÂÂÂÂ label = "lp-led1";
>>
>> ÂÂÂÂÂÂÂÂ // This specifies LED number within lp5024
>> ÂÂÂÂÂÂÂÂ led-index = <1>;ÂÂ // set output-base as 1*3 == 3
>>
>> ÂÂÂÂÂÂÂÂ element-red {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT3
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <0>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂÂÂÂ element-green {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT4
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <1>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂÂÂÂ element-blue {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to OUT5
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <2>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂ};
>>
>> ÂÂÂÂÂbank-led {
>> ÂÂÂÂÂÂÂÂ // this will create led instance for bank leds in lp5024
>> ÂÂÂÂÂÂÂÂ label = "lp-bank-led";
>>
>> ÂÂÂÂÂÂÂÂ // configured bank led configuration
>> ÂÂÂÂÂÂÂÂ led-index = <2 3 4 5 6 7>;
>> ÂÂÂÂÂÂÂÂ // As here is list of led-indices this entry is
>> ÂÂÂÂÂÂÂÂ // assumed to be bank configuration. Bank mode is enable
>> ÂÂÂÂÂÂÂÂ // for the indices.
>>
>> ÂÂÂÂÂÂÂÂ // set output-base as BANK A
>>
>> ÂÂÂÂÂÂÂÂ element-red {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to BANK A
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <0>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂÂÂÂ element-green {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to BANK B
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <1>;
>> ÂÂÂÂÂÂÂÂ };
>>
>> ÂÂÂÂÂÂÂÂ element-blue {
>> ÂÂÂÂÂÂÂÂÂÂÂÂ // refers to BANK C
>> ÂÂÂÂÂÂÂÂÂÂÂÂ output-offset = <2>;
>> ÂÂÂÂÂÂÂÂ };
>> ÂÂÂÂÂ};
>> };
>>
>> 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:
>>
>> ÂÂÂÂÂbrightness-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.

+1 to that comment

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


-- 
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Dan Murphy