[Display] Low contrast when setting Power Profile to "Power Save" and on battery

[questionlp]

Per this Reddit thread, there is a known behavior where the laptop display panel will run in low power mode when running on battery and the Power Profile is set to "Power Save". This causes the screen to have reduced contrast.

Per a comment in the thread, setting /sys/class/drm/card1-eDP-1/amdgpu/panel_power_savings to 0 (the value is set to 3 in Fedora 40 with power-profiles-daemon version 0.2.1) will disable the panel's power saving.

Unfortunately, that reverts back to 3 if I connect the laptop back to the charger and disconnect it again.

A more permanent solution should be implemented, including settings available in KDE.

Leaving this issue open until then.

[questionlp]

Found the following in the README.md in the power-profiles-daemon repository:

---

Laptops with integrated Radeon graphics have a dedicated hardware function
to decrease panel power consumption in exchange for color accuracy. This
function is used when the system is on battery and the user has selected
the "balanced" or "power-saver" profiles.

If you decide that you don't like how this behaves, you can disable the function
in one of two ways:

1. Adding amdgpu.abmlevel=0 to the kernel command line. This will disable abm
   value changes entirely.
2. By using --block-action=amdgpu_panel_power in the
   power-profiles-daemon ExecStart command. This will allow you to
   still change values manually in sysfs but power-profiles-daemon will not
   change anything.

---

I opted to use the second option and the value seems to stick to 0 after making the change, running sudo systemctl daemon-reload && sudo systemctl restart power-profiles-daemon.

Marking this issue as closed.