[Intel-gfx] [alsa-devel] [PATCH 0/4 V7] Power-well API implementation for Haswell

[Wang, Xingchao]

> -----Original Message-----
> From: Wysocki, Rafael J
> Sent: Wednesday, July 24, 2013 9:15 PM
> To: David Henningsson
> Cc: Wang, Xingchao; Takashi Iwai; Paulo Zanoni; Daniel Vetter;
> daniel.vetter at ffwll.ch; alsa-devel at alsa-project.org;
> intel-gfx at lists.freedesktop.org; Girdwood, Liam R; Jin, Gordon
> Subject: Re: [alsa-devel] [Intel-gfx] [PATCH 0/4 V7] Power-well API
> implementation for Haswell
> 
> On 7/24/2013 1:57 PM, David Henningsson wrote:
> > On 07/24/2013 01:33 PM, Wang, Xingchao wrote:
> >> Yes, I agree. I'm debugging this issue on Ubuntu, not sure it happens
> >> on other distribution too.
> >> If it's related to Ubuntu, maybe need check Ubuntu power policy. Does
> >> anyone know the Ubuntu power-policy on laptop?
> >> i.e. when charger connected, will Ubuntu make decision to disable
> >> power-save feature for audio subsystem?
> >
> > I'm not a power management expert, but I got a pointer from my team
> > mate to pm-utils:
> >
> > http://cgit.freedesktop.org/pm-utils/tree/pm/power.d/intel-audio-power
> > save
> >
> >
> > If I understand correctly, The scripts in power.d are executed when
> > battery / AC-power is changed.
> >
> 
> To me, this sounds like a user space issue.  It requested power on and the
> kernel delivered.

Do you know which user-space application will touch below two flags?
- /sys/devices/pci0000\:00/0000\:00\:03.0/power/control
- /sys/module/snd_hda_intel/parameters/power_save

Thanks
--xingchao
> 
> Trying to modify the kernel to work around that would be insane.
> 
> Thanks,
> Rafael