@Thomas J Moore

My HP laptop with AMD A10-7300 (Kaveri iGPU, Topaz dGPU) has a fully working X
up to kernel 4.9 (not beyond) with these module options applied as such :

# cat /etc/modprobe.d/amdgpu.conf 

install radeon /bin/false
options amdgpu aspm=0 bapm=0 runpm=0 powerplay=1

In case it helps.