AC-adapter unplugged:
$ echo power | sudo tee energy_performance_preference
power
$ echo $?
0
AC-adapter plugged-in:
$ echo power | sudo tee energy_performance_preference
power
tee: energy_performance_preference: Device or resource busy
Yes, I have intel p-states HWP-capable CPU, otherwise i wouldn't have that setting above.
My laptop is running Gentoo Linux hardened with 5.17.4-gentoo-x86_64 kernel.
Maybe it's somehow related, but /var/log/syslog shows that after unplugging adapter:
May 27 17:19:27 mathroom laptop-mode: enabled, active
May 27 17:19:27 mathroom rfkill: block set for type bluetooth
May 27 17:19:27 mathroom laptop-mode: LCD Brightness Command succeeded.
May 27 17:19:27 mathroom kernel: EXT4-fs (sda3): re-mounted. Quota mode: disabled.
May 27 17:19:27 mathroom kernel: EXT4-fs (sda4): re-mounted. Quota mode: disabled.
May 27 17:19:27 mathroom kernel: r8169 0000:02:00.0 enp2s0: Link is Down
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000081 00000001
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:19:28 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000001 00000001
, and this after plugging it back in:
May 27 17:20:36 mathroom laptop-mode: enabled, active
May 27 17:20:36 mathroom rfkill: unblock set for type bluetooth
May 27 17:20:36 mathroom laptop-mode: LCD Brightness Command succeeded.
May 27 17:20:36 mathroom kernel: NMI watchdog: Enabled. Permanently consumes one hw-PMU counter.
May 27 17:20:36 mathroom kernel: EXT4-fs (sda3): re-mounted. Quota mode: disabled.
May 27 17:20:36 mathroom kernel: EXT4-fs (sda4): re-mounted. Quota mode: disabled.
May 27 17:20:36 mathroom kernel: r8169 0000:02:00.0 enp2s0: Link is Down
May 27 17:20:36 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:20:36 mathroom root: ACPI event unhandled: ac_adapter ACPI0003:00 00000080 00000001
May 27 17:20:37 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000081 00000001
May 27 17:20:37 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000080 00000001
May 27 17:20:37 mathroom root: ACPI event unhandled: battery PNP0C0A:00 00000001 00000001
Also, there's no diff-erence in /etc/mtab before and after changing adapter state.
It's worth noting that at the time ac-adapter IS connected, i CAN write to scaling_governor, for example, but not to energy_performance_preference.
This post didn't help me(lsof +D /sys output is unrelated).
Any help will be appreciated.
