Hi, I use r9 280x, and I also have problems, but on the 4.18 core + (radeon.si_support = 0 amdgpu.si_support = 1 modprobe.blacklist = radeon) everything works well, they do it right, they make their driver open and make it part of the system right away, it will take a couple of years and we will begin to appreciate it for real)
sorry for my google translate