On Wed, 3 Feb 2021 17:35:55 +0100
Pavel Machek <pavel@xxxxxx> wrote:
> On Wed 2021-02-03 15:39:59, Sven Schuchmann wrote:
> > Hello Pavel,
> >
> > > > In order to use a multicolor-led together with a trigger
> > > > from DT the led needs to have an intensity set to see something.
> > > > The trigger changes the brightness of the led but if there
> > > > is no intensity we actually see nothing.
> > > >
> > > > This patch adds the ability to set the default intensity
> > > > of each led so that it is turned on from DT.
> > >
> > > Do we need this to be configurable from device tree? Can we just set
> > > it to max or something?
> > >
> > > Aha, this basically sets the initial color for LEDs the monochromatic
> > > triggers, right?
> >
> > Let me try to explain in other words: I have one RGB-LED
> > which consists of 3 Colors. Each of the three colors (Red, Green, Blue) you have
> > to define in the DT. For example this is my setup for one RGB-LED which I wanted
> > to show the heartbeat in Red (half intensity):
> >
> > multi-led@3 {
> > #address-cells = <1>;
> > #size-cells = <0>;
> > reg = <0x3>;
> > color = <LED_COLOR_ID_RGB>;
> >
> > linux,default-trigger = "heartbeat";
> > function = LED_FUNCTION_HEARTBEAT;
> >
> > led-9 {
> > color = <LED_COLOR_ID_RED>;
> > default-intensity = <100>;
> > };
> >
> > led-10 {
> > color = <LED_COLOR_ID_GREEN>;
> > };
> >
> > led-11 {
> > color = <LED_COLOR_ID_BLUE>;
> > };
> > };
> >
> > If I would not have the default-intensity I would actually see nothing,
> > since the intensity (which goes from 0-255) of each led is initialized with 0.
> >
> > I hope I could clarify this a little more?
>
> Yes, sounds reasonable. Could we get default intensity of 100% on all
> channels if nothing else is specified?
>
> Or maybe simply "if intensity is not specified, start with 100%, and
> use explicit =0 if other color is expected".
>
> Best regards,
> Pavel
Is the property default-intensity documented in DT bindings?
Wouldn't it be better if the property was used in the multi-led node
instead of the channel node? I.e.
multi-led@3 {
color = <LED_COLOR_ID_RGB>;
default-intensity = <100 0 0>;
};
