[alsa-devel] ALC268 - Driving mute led with GPIO

Takashi Iwai tiwai at suse.de
Thu Feb 4 18:11:18 CET 2010

At Thu, 04 Feb 2010 19:04:50 +0200,
Ozan Çağlayan wrote:
> Takashi Iwai wrote:
> > At Thu, 04 Feb 2010 18:44:48 +0200,
> > 
> > This can be rather controlled in a different way, such as GPIO.
> > 
> > For example, if it's a HP machine, usually one of GPIO line
> > corresponds to the mute LED (sometimes it mutes the speaker via
> > BIOS).
> > 
> Um, that was what I thought and tried to ask too :)
> So how should I proceed to make it work upon mutes? There are 4 GPIO lines and the last one seems to control
> the mute LED but it doesn't mute the speaker.
> Can it be done asynchronously with a callback which will send 1/0 to the GPIO channel on every mute/unmute?
> Or should that be done synchronously in the code where the mute/unmute verbs are executed?

Simply depending on the implementation.
Either change the control put callback to toggle the GPIO in sync with
the mute state, or use power check callback like in patch_sigmatel.c.

> There are currently mute LED handlings only in sigmatel for some HP laptops which parses DMI data for the
> exact GPIO channel.

A similar thing is found for AD198x HP laptops.


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