FR: allow fine-tuned voltage/frequency control

[preda]

amdgpu-pro allows setting the frequency and voltage per power state by writing to
/sys/class/drm/card0/device/pp_od_clk_voltage, e.g.:
echo "s 4 900 1050" > pp_od_clk_voltage
echo c > pp_od_clk_voltage
as described here:
https://www.reddit.com/r/Amd/comments/8weeln/you_can_undervolt_vegas_in_linux_now/

Could ROCm offer a similar functionality?

[preda]

Similar to what is described in: #463
but could this be in ROCm "out of the box" instead of requiring custom compilation as described there.

[preda]

Interesting, this seems to be working with ROCm 1.8.2 with Fiji GPUs, but not with Vega.

[  405.541346] amdgpu: [powerplay] pp_odn_edit_dpm_table was not implemented.

[preda]

pp_od_clk_voltage also works "out of the box" in kernel 4.18 (Ubuntu 18.04). It would be so nice if the next ROCm would work on this kernel.. (4.18)

[preda]

This seems to work with ROCm too, closing.