On Tue, Nov 25, 2008 at 10:42:36AM -0800, David Brownell wrote:
> There are actually four PWM signals ... two associated with LEDs
> (or VIBRA.M, or VIBRA.P; high current) with fast input clocks,
> then PWM0 and PWM1 with slower input clocks which are alternate
> GPIO settings. PWM1 can be used as VIBRA.SYNC.
>
> The two LED PWMs are used as GPIOs on the Beagle ... so the GPIO
> driver supports them as output-only GPIOs, setting the LED PWMs
> up to be "always on" or "always off".
>
> In short: all the PWM-equipped pins have "clean" driver support,
> but only for using them as GPIOs, not as PWM.
Henrik Saari, Cced, actually wrote the twl4030-vibra driver and, afaict,
it's using the LED Class. Henrik, do you wanna share the code ?? :-)
> Right now, just use LEDA and LEDB as GPIO-19 and GPIO-20, like
> Beagle does; ditto for PWM-0/GPIO-6 and PWM-1/GPIO-7.
>
> Near term, something to support led_classdev.brightness_{set,get}
> methods would make sense to me, for LEDA and LEDB. The EVMs could
> set up LEDA devices and hook them up to the "backlight" trigger.
> The same thing could be done for PWM0 and PWM1.
>
> Long term, we may have a PWM framework ... but it's not ready yet,
> and hasn't even been refreshed recently either. And so far as I
> know, ALSA has no notion of supporting the VIBRA module hookup
> options for "audio" output.
I think for now, we can keep it as LED driver, then ?
--
balbi
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