[alsa-devel] [PATCH] ALSA: hda - Make sure mute LEDs stay on during runtime suspend (Realtek)

[David Henningsson]

On 11/06/2013 11:11 AM, Takashi Iwai wrote:
> At Wed,  6 Nov 2013 10:50:44 +0100,
> David Henningsson wrote:
>>
>> Some HP machines with Realtek codecs have mute LEDs connected to VREF pins.
>> However when these go into runtime suspend, the pin powers down and its
>> pin control is disabled, thus disabling the LED too.
>>
>> This patch fixes that issue by making sure that the pin stays in D0 with
>> correct pin control.
>>
>> Cc: stable at kernel.org
>> BugLink: https://bugs.launchpad.net/bugs/1248465
>> Tested-by: Franz Hsieh <franz.hsieh at canonical.com>
>> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
> 
> Thanks, applied.
> 
> I do wonder, though, whether the LED survives even after turning AFG
> to D3.  With IDT codecs, we had to keep AFG D0 just for keeping this
> VREF stuff.  Maybe Realtek codecs behave differently.

Well, the patch was tested by Franz and found working, so it seems
indeed that AFG can be in D3 and the LED still works.

(Actually it could even be the other way around - maybe even the pin can
remain in D3 and still have vref output, as long as the pin ctl is set.
I never tested that explicitly.)

-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic