Created attachment 141002 [details]
dmesg for 4.17.11-200

When booting kernel 4.17 or 4.18-rc8+ (git) on a POWER9 system with an ASUS Rx
580 GPU, the following messages are printed to the kernel log:

[   10.398837] amdgpu: [powerplay] There must be 1 or more PCIE levels defined
in PPTable.
[   10.398839] amdgpu: [powerplay] Failed to populate SCLK during
PopulateNewDPMClocksStates Function!
[   10.398840] amdgpu: [powerplay] Failed to populate and upload SCLK MCLK DPM
levels!


Note that the system is booted with the kernel argument `amdgpu.dc=0` to work
around this issue: https://bugs.freedesktop.org/show_bug.cgi?id=107049

GPU performance seems to be significantly hindered as a result of these errors.

Booting with `amdgpu.dpm=0` silences the errors but does not improve
performance.