Comment # 29 on bug 108781 from pascalp

For me it is the other way round:
With my 290x I used to boot fine under 4.18 without amdgpu.dpm set at all.
After updating to 4.19 and being unable to boot I read that amdgpu.dpm defaults
to "enabled" so I explicitly had to add amdgpu.dpm=0 to be able to boot again.
amdgpu.dc does not matter in this context - both 0 and 1 work as long as dpm is
disabled. This is on an unpatched kernel (4.19.4 currently).