[pulseaudio-discuss] Soundcard's powersave mode

[Mikhail Morfikov]

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In the case of snd_hda_intel kernel module, there's two options called
power_save and power_save_controller . I've set them to the following
values:

# systool -v -m snd_hda_intel | grep power
    power_save          = "10"
    power_save_controller= "Y"
    
According to archlinux wiki (https://wiki.archlinux.org/index.php/Power_management#Audio),
the power_save parameter is measured in seconds, and it should idle the
audio card after 10s.

The question is how could I know whether this works or not? Is there
any way to be sure that the powersave mode was activated? I've heard
that there's could be some "clicking" when the state of the sound
card changes, but I don't hear anything. Some people reported that the
volume behaves really strange, but it seems that it works just fine on
my machine.

Does the powersave mode in the kernel module is somehow related to the
following output?

$ pacmd list-sinks | egrep -i "state|suspend"
        state: SUSPENDED
        suspend cause: IDLE

I noticed that when some app plays audio stream, the state becomes
RUNNING. When the app stops playing, the state changes to IDLE, and
about 5s later, it changes to the state that you can see above. This
behavior is the same no matter what I set in the power_save option
in the kernel module. I've tested 0, 1 and 10, and actually I didn't
notice any difference.

So, is the powersave mode enabled or not?
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