With the openSUSE Tumbleweed update to kernel 4.4, my secondary display went
dark.
This is on a Sandybridge graphics system (i7-2600K) with an Intel mainboard
(DH67CL), the same problem persists with 4.4.1 and 4.5-rc1 kernels from OBS
(Kernel:Stable and Kernel:HEAD), while a 4.3.3 from home:tiwai:kernel:4.3 makes
the display connected to "HDMI2" (actually the DVI connector) work again fine -
the main display on "HDMI1" (HDMI connector of the mainboard) works fine with
all those kernel variants.

I filed https://bugs.freedesktop.org/show_bug.cgi?id=94299 for this as well on
the upstream side.