https://bugs.freedesktop.org/show_bug.cgi?id=96868

--- Comment #16 from Jonas jojonintendo@tutanota.com --- (In reply to Andy Furniss from comment #15)

You should be able to do this eg. on my R9 285

echo manual > /sys/class/drm/card0/device/power_dpm_force_performance_level

cat /sys/class/drm/card0/device/pp_dpm_mclk 0: 150Mhz * 1: 1375Mhz

echo 1 > /sys/class/drm/card0/device/pp_dpm_mclk

cat /sys/class/drm/card0/device/pp_dpm_mclk 0: 150Mhz 1: 1375Mhz *

Though it will undo if you change modes or go into DPMS.

I can't apply "manual" mode: "invalid argument". I can't see pp_dpm_mclk clocks either.