Power-saving/performance toggles for amdgpu

[Bastien Nocera]

Hey,

I'm currently working on a daemon that allows a UI that will eventually
look like the power mode section in this mockup:
https://gitlab.gnome.org/Teams/Design/settings-mockups/-/blob/master/power/power.png

The daemon:
https://gitlab.freedesktop.org/hadess/power-profiles-daemon
The UI:
https://gitlab.gnome.org/GNOME/gnome-control-center/-/merge_requests/816

It might be interesting, on some systems, to nudge the GPU drivers
in the direction wanted by the user, either enabling aggressive power-
saving or allowing more power to be used for better temporary
performance.

I was wondering whether the tweaks
in /sys/class/drm/card*/device/power_profile
and /sys/class/drm/card*/device/power_method were things that this
daemon could and should tweak, or whether it was present solely for
debug purposes and shouldn't be needed even when high performance or
power-saving is wanted:
https://gitlab.freedesktop.org/hadess/power-profiles-daemon/-/issues/3

Thanks in advance!