Comment 1 for bug 1205263

Here's an email with more information (reference: http://mailman.alsa-project.org/pipermail/alsa-devel/2013-July/064462.html )

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Hi Takashi,

In order to let audio power-save work even with charger connected, two parameters need be modified in userspace pm-utils scripts.
I tested the changes under Ubuntu 13.10 on Harris Beach, no matter charger connected or not, runtime power-saving works and power-well will
Be released as expected.

Here's my test under Ubuntu 13.04, the changes are:
1)
/usr/lib/pm-utils/power.d/intel-audio-powersave
case $1 in
    true) audio_powersave 1 ;;
+ false) audio_powersave 10 ;;
- false) audio_powersave 0 ;;
    help) help;;
    *) exit $NA
esac

Audio will enter power-save mode after 10s inactive period.
2) /usr/lib/pm-utils/power.d/pci_devices

     0x040300) # audio
        echo "Setting Audio device $id to $1"
+ echo "auto" > $dev/power/control
- echo $1 > $dev/power/control

This keep audio subsystem always on.

This way the user may not let audio subsystem always active, may bring some delay from codec/controllers, or harm some chips.
Do you think we should add an exception for Haswell only or just make it as a common solution for audio subsystem?

Thanks
--xingchao
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