https://bugs.freedesktop.org/show_bug.cgi?id=76490
--- Comment #113 from Alex Deucher alexdeucher@gmail.com --- (In reply to Daniel Exner from comment #112)
If I read that correct R9 270X is a GCN 1.0 card and thus should be supported by experimental drm-next-4.8-wip-si branch.
Is it worth trying? AMDGPU is using a yet another PM system (PowerPlay) , so perhaps it works better, without having to blacklist?
That tree is using the same code power management as radeon, just ported to amdgpu.