Public bug reported:
I use an Sony Vaio SZ2M-B, which is a 13" subnotebook. As you may think I hear
a "pop" due to power saving, which doesn't annoy me. What annoys me is that
through the acpi-driver my notebook has the capability to power down the hole
audio device, which saves even MORE power and this works without a hearable
noise. In Jaunty I had scripts in /etc/acpi/ac.d and battery.d which did power
off my audio, when I was on battery, but these directories seem to be obsoleted
in Karmic.
The Idea of powering on the chip by demand is even better, than these scripts,
which annoyed me sometimes. So if it is possible to check if the driver
sony_laptop is loaded and to check if the file
/sys/devices/platform/sony-laptop/audiopower exists you could on some notebooks
even more power saving.
One can turn off the audio power by executing "echo 0 >
/sys/devices/platform/sony-laptop/audiopower" and turn on by echoing 1 instead
of 0.
This has only one disadvantage: turning on and off takes time, which is
noticeable, and which might be too much for simple notifications in e.g.
pidgin. I estimate the delay to 0.5s.
I don't expect you to implement this, it is just a suggestion. I would
be happy if you could just tell me, which file to modify for powering my
audiochip totally on demand.
btw. sony_laptop offers powering off more devices, e.g. wwan, bluetooth
and cd power.
ProblemType: Bug
AplayDevices:
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
Architecture: i386
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: lutz 2697 F.... pulseaudio
Card0.Amixer.info:
Card hw:0 'Intel'/'HDA Intel at 0xdc340000 irq 21'
Mixer name : 'SigmaTel CXD9872RD/K'
Components : 'HDA:83847661,104d0700,00104201
HDA:14f12bfa,104d0200,00090000'
Controls : 13
Simple ctrls : 9
Date: Sat Aug 15 13:23:49 2009
DistroRelease: Ubuntu 9.10
Package: alsa-base 1.0.20+dfsg-1ubuntu4
PackageArchitecture: all
ProcEnviron:
PATH=(custom, user)
LANG=de_DE.UTF-8
SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-5.24-generic
SourcePackage: alsa-driver
Uname: Linux 2.6.31-5-generic i686
** Affects: alsa-driver (Ubuntu)
Importance: Undecided
Status: New
** Tags: apport-bug i386
--
[9.10 regression] HDA power_save=10
https://bugs.launchpad.net/bugs/414012
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