-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Wednesday, July 24, 2013 9:43 PM To: Wang, Xingchao Cc: Wysocki, Rafael J; David Henningsson; Paulo Zanoni; Daniel Vetter; daniel.vetter@ffwll.ch; alsa-devel@alsa-project.org; intel-gfx@lists.freedesktop.org; Girdwood, Liam R; Jin, Gordon Subject: Re: [alsa-devel] [Intel-gfx] [PATCH 0/4 V7] Power-well API implementation for Haswell
At Wed, 24 Jul 2013 13:30:16 +0000, Wang, Xingchao wrote:
-----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@ffwll.ch; alsa-devel@alsa-project.org; intel-gfx@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-p ower 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
The latter is touched most likely by pm-utils, one of the hooks, as David pointed.
Oh yes I found the hook: ./pm/power.d/intel-audio-powersave
--xingchao
The former is unknown, but better to check pm-utils hooks and udev rules.
Takashi