well, today i (partially) realized why my basic drivers don’t work: the preinstalled packages amdgpu and amdgpu-dkms seem to not work due to amdgpu-dkms being unconfigured. tried configuring it and got the same error. around about there my system stopped using even the iGPU and i had to uninstall some other drivers (thanks @lena@gregtech.eu )
My R9 390 was a huge pain in the ass to get working on any distro, but I think it was the last card before they fixed whatever issue it was.
Yeah, afaik it’s exactly one of the cards that require manual intervention or a switch to the radeon driver. Bad generation to run on Linux.