https://bugs.freedesktop.org/show_bug.cgi?id=91880
--- Comment #206 from Sandeep sandy.8925@gmail.com --- You've got to make sure that radeon and amdgpu drivers don't clash.
Try the following kernel parameters: radeon.si_support=0 radeon.cik_support=0 amdgpu.si_support=1 amdgpu.cik_support=1 amdgpu.dpm=1
That's what I use and it works fine for me.