Re: [PATCH v14 2/2] leds: Add driver for Qualcomm LPG

Pavel Machek
2022-05-06T16:09:50Z

Hi!

> > > + "255 500 0 500"
> > > +
> > > + ^
> > > + |
> > > + 255 +----+ +----+
> > > + | | | | ...
> > > + 0 | +----+ +----
> > > + +---------------------->
> > > + 0 5 10 15 time (100ms)
> > > +
> > > +The LPG supports specifying a longer hold-time for the first and last element
> > > +in the pattern, the so called "low pause" and "high pause".
> >
> > Please see
> > Documentation/devicetree/bindings/leds/leds-trigger-pattern.txt . This
> > should really be compatible.
>
> Unfortunately the LPG hardware only supports fixed duration (except for
> the ability to hold/extend the first and last duration in the pattern)
> and it also does not support gradual transition between the brightness
> levels.

Ok.

> As such the pattern sequence provided to hw_pattern looks to be the
> smae, but I don't see that it can be made compatible.
>
> > Can I get either patch to disable pattern infrastructure for now or to
> > get it compatible?
> >
>
> I'd be happy to get this updated to your liking, but this was one of the
> drivers we discussed when we introduced the pattern trigger and led to
> the conclusion that we need the ability to do hw-specific patterns.
>
> As such this document provides the hardware specific documentation, as
> we describe under "hw_pattern" in
> Documentation/ABI/testing/sysfs-class-led-trigger-pattern.
>
> Please advice on what you would like me to do.

I'd like you to use same format leds-trigger-pattern describes.

If someone passes "255 500 0 500", that's requesting gradual transitions and
your hw can not do that. You return -EINVAL.

If someone wants that kind of blinking, they need to pass "255 0 255 500 0 0 0 500".

Best regards,
Pavel

-- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures)