Re: [PATCH] pwm-backlight: Add support for active low PWM backlights

[Alban Bedel <alban.bedel@avionic-design.de>]

On Tue, 6 Nov 2012 07:44:06 +0100
Thierry Reding <thierry.reding@avionic-design.de> wrote:

> > --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
> > +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
> > @@ -14,6 +14,7 @@ Required properties:
> >  Optional properties:
> >    - pwm-names: a list of names for the PWM devices specified in the
> >                 "pwms" property (see PWM binding[0])
> > +  - active-low: boolean indicating that the backlight use active low logic
> 
> Couldn't you use the brightness-levels property to achieve the same
> effect?

Not in the current state as the curve currently hardcode the fact the
first element have 0% duty and the last 100%. But relaxing this
limitation is probably better as it would also allow clamping the curve
like the lth_brightness parameter do when no curve is used.

I'll send a new patch implementing this soon.

Alban