I read somewhere that if you're running the newest Ubuntu 16.04, they switched to OPENAMD drivers instead of the proprietary ones, and it wasn't recommended to use AMD at this time because it is very new and being tested. Using a version prior to 16.04 should still work to the best of my knowledge.
is interesting to me. I will most definitely be using 16.04. I have been anxiously awaiting the release. That combined with Wine 2.0 is going to make this year for me. I can cut windows out after I have DX11
There is also AMD-PRO beta drivers that should work in 16.04 lts. As for AMDGPU, yes you need CIK enabled, blackscreen/freezing can also be related to bad powerstate settings (no easy fix for this, magic tty commands needed).
Seems now that my 390x is dead in RMA (taking FOREVER to come back to me), EVERYONE is trying their AMD cards under Linux again! so I can't directly help because I'm almost 5 weeks out of date with anything Linux as I wait here in Windows 10 for 390x return ;-(