Comment # 5 on bug 1006420 from Takashi Iwai

Try to boot with drm.debug=0x0e and get the kernel messages on both working
(4.7.x) and broken (4.8.x) kernels -- supposing it worked on 4.7.x.
Then please report this to upstream, bugzilla.freedesktop.org, together with
these kernel messages and the detailed hardware information.  Use DRI / Nouveau
category there.