Comment # 1 on bug 111762 from tempel.julian@gmail.com

Still happens with current 5.5-wip/drm-next kernels.
I don't know if it is supposed to be implemented, but there seems to be some
bug apart from that:
Just reading sysfs entries at "/sys/class/drm/card0/device/" makes the parsing
program freeze, e.g. filebrowser (also if started as root).

Anyhow, "# cat /sys/class/drm/card0/device/pp_od_clk_voltage" returns nothing.

Could there be an update on this? Not being able to overclock/undervolt almost
4 months after Navi release is a huge disappointment.