Hi!
> > > > Signed-off-by: Sven Schwermer <sven.schwermer@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> > > > ---
> > > [...]
> > > > +
> > > > +additionalProperties: false
> > > > +
> > > > +examples:
> > > > + - |
> > > > + #include <dt-bindings/leds/common.h>
> > > > +
> > > > + rgb-led {
> > > > + compatible = "pwm-leds-multicolor";
> > > > +
> > > > + multi-led {
> > > > + color = <LED_COLOR_ID_RGB>;
> > > > + function = LED_FUNCTION_INDICATOR;
> > > > + max-brightness = <65535>;
> > >
> > > It doesn't make much sense to have such a big resolution of global
> > > multi color brightness. 255 will be sufficient.
> >
> > If the PWM supports it, why not?
> > On Omnia the default is 255, and since it is PWM, the change from 0/255
> > to 1/255 is much bigger then from, say, 15/255 to 16/255. So if 1/255
> > is too bright, you are then unable to set it less bright. I think 1024
> > or ever 65535 makes sense with PWMs.
>
> With values other than 255 we will not achieve 24-bit RGB, which is one
> problem, and the other one is non-linear brightness that can be achieved
> with PWM. So probably we would need to add an additional note in the
> documentation [0], saying that changing global brightness allows to
> preserve combined LED hue only when all sub-leds are linear, and that it
> will not be the case for PWM LEDs.
I have yet to see a LED that was anything but linear. If we'll want to
match colorspace of RGB displays, we'll need to do more work. (Often,
255/255/255 is not white with RGB LEDs, for example).
So 16-bit pwm makes sense to me.
Best regards,
Pavel
--
http://www.livejournal.com/~pavelmachek
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