Re: best way to handle LEDs

[Pavel Machek <pavel@suse.cz>]

Hi!

> > > > yellow off: 	not charging
> > > > yellow on:	charging
> > > > yellow fast blink: charge error
> > > > 
> > > > I think even slow blinking was used somewhere. I have some code from
> > > > John Lenz (attached); it uses sysfs interface, exports led collor, and
> > > > allows setting different frequencies.
> > > > 
> > > > Is that acceptable, or should some other interface be used?
> > > 
> > > IMHO reducing digital outputs to LEDs goes not far enough. All System-
> > > on-Chip CPUs have General Purpose I/O pins today, which can act as
> > > inputs or outputs and may be used for LEDs, matrix keyboard lines,
> > 
> > We have some leds that are *not* on GPIO pins (like driven by
> > ACPI). We'd like to support those, too.
> 
> I though ACPI was software? These LEDs have to be driven by some hardware,
> right?

Right, but you don't know by *which* hardware. Only ACPI AML code knows.
So from linux POW, they are handled by ACPI.

It may even trap to SMM BIOS.
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