Comment # 5 on bug 95131 from Daniel Scharrer

Same issue here:

Distribution: Gentoo
GPU: R9 380X (TONGA)
Display connector: DVI
xf86-video-amdgpu: git-60ced50
X server: 1.17.4
Mesa: git-d98d6e6
libdrm: git-7aab852
Kernel: 4.6.0

I can confirm it works with the DAL enabled in the drm-next-4.7-wip-dal branch
of https://cgit.freedesktop.org/~agd5f/linux/ (the drm-next-4.8-wip-dal branch
locks up during boot).