Cycles on linux with r9 390

I’m trying to set up a GPU render to work on Linux Mint 18 Cinnamon, with a R9 390.
As I see I cannot use proprietary drivers from AMD 'cause they are not more supported by Ubuntu 16.04 (Linux Mint 18 is based on Ubuntu 16.04). By the way I tried to install them (15.12 Crimson) without success (DKMS issue).
I also tried to use AMDGPU-PRO (16.30 beta) but without success for now (black screen at login. GCN 1.1 not official supported).
How can I use GPU computing on Linux with an AMD card? I need to use an oldest linux distro with proprietary drivers?

Some specs:
Linux Mint 18 Cinnamon.
Kernel 4.4.0-28.
AMD R9 390.

If you need some logs, just ask.