Re: [RFE] Power down AC'97 when muted

[Takashi Iwai <tiwai@suse.de>]

At Wed, 22 Dec 2004 20:41:23 +0100,
Pierre Ossman wrote:
> 
> I have a request for a new feature in the AC97 driver (my card is an 
> intel ICH4). I'd like to see the driver power off the AC97 part when the 
> master volume is muted. Currently the power control has a seperate 
> volume control that can be used.
> 
> The reason I want this is because my laptop has a LED indicating mute 
> status. This is triggered by the power down function of the AC97 function.
> 
> Since the power is exposed through a volume control this could be done 
> in user space, but that would me that every program that mutes the sound 
> card would need special logic to see if the card has an "External 
> amplifier" (as the channel is called). Therefore it seems much better to 
> do this in the driver.
> 
> Another point is that Windows seems to have this behaviour (since the 
> LED functions fine there in every application) so manufacturers rely on 
> this (HP in my case).
> 
> I tried doing this myself by adding an extra call inside 
> ac97_put_double() checking for changes to the master channel but I 
> couldn't get it to work. I just got a faint flicker out of the LED. If 
> people give me enough pointers I might be able to put together a patch 
> for this.

It's BUG #667, right?
	https://bugtrack.alsa-project.org/alsa-bug/view.php?id=667

I uploaded a test patch there.  Please give it a try.



Takashi


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