Comment # 1 on bug 101026 from Harry Wentland

Hi Liam,

I haven't tried it myself but I don't think this will work with the upstream
amdgpu driver. You can try Alex's amd-staging-4.9 or amd-staging-4.11 trees and
enable CONFIG_DRM_AMD_DC to get support for our new display driver which is not
upstream yet. That should give you support for 4k60 over HDMI.

I don't think Mesa has anything to do with this.

Cheers,
Harry