mjhjmtu

I've run into a peculiar issue. Let me describe:

1. On boot, from GRUB I pass arguments snd_hda_intel.power_save=0 snd_hda_intel.power_save_controller=N


2. Laptop mode tools starts up, power saving for snd_hda_intel is disabled:

https://pastebin.com/R6SMzTAT

3. /sys/module/snd_hda_intel/parameters/power_save is set to 0, but the system still shows power saving behavior - the characteristic clicking in headphones a while after stopping sound playback, and again when starting sounding as the card powers on.




4. If i use powertop, go to Tunables, it says Audio codec power management is off. Now, if here, pressing Enter is turn the power management on and then off, the issue is fixed, no more power saving. I'm puzzled why this is needed though. Also, maybe im being silly, but powertop claims it runs the command
   echo '' > '/sys/module/snd_hda_intel/parameters/power_save';

to turn this off. Running this from the terminal however gives an error

bash: echo: write error: Invalid argument

I can do

echo '0' > /sys/module/snd_hda_intel/parameters/power_save

but that parameter is supposedly already set to 0, and this command doesn't fix the issue. I need to enable and disable in powertop.

Any explanation for this and how to fix it without having to do the powertop trick afer every boot? And why does powertop claim to run a command that gives an error when I try top execute it?

Some more info:

Linux gentoo 4.19.1-gentoo #1 SMP Mon Nov 5 21:27:35 CET 2018 x86_64 Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz GenuineIntel GNU/Linux

Sound card:

 00:1f.3 Audio device: Intel Corporation 100 Series/C230 Series Chipset Family HD Audio Controller (rev 31)

EDIT: Also an interesting fact - if I do the powertop thing, and then stop laptop mode tools:

systemctl stop laptop-mode

that causes the power saving behavior to come back, and the powertop trick is needed. So clearly laptop mode tools does something weird here. Booting the system with laptop mode tools disabled makes everything okay too - no annoying power saving on the sound card.