Re: [PATCH v2 1/2] led: led-class: Read max-brightness from devicetree

[Jacek Anaszewski]

Hi Astrid,

On 7/3/23 09:53, Astrid Rost wrote:
> Hello Jacek,
>
> I am having problems with the PWM controller LP5024.
>
> https://www.ti.com/product/LP5024
>
> There is no such a calculation in the data-sheet like:
> max_brightness = max_current / constant.
>
> I also assume it is depending on the type of LEDs and circuit, which are 
> connected.
>
> It supports two current modes: 25,5 mA and and 35 mA, both is to high 
> for the LEDs I have.
>
> For max_brightness seems to be everything inside the kernel, but reading 
> the value from devicetree. I first thought I could add it in the lp50xx
> driver, but Andy and Rob thought that I better put it into the general 
> parts. And of course drivers having led-max-microamp should better use it.
>
> Please, let me know if you have a better suggestion.

OK, since this LED controller is PWM-driven then there is no current per
brightness level granulation. Bindings of leds-pwm driver also use
max-brightness DT property. So, yeah, let's make it a common property,
but state clearly that it is mainly for drivers like PWM ones, where it
is not possible to map brightness level to the amount of current.

--
Best regards,
Jacek Anaszewski