Comment # 7 on bug 997503 from Takashi Iwai

(In reply to Rich Coe from comment #0)
> On Saturday I updated from Tumbleweed to the latest Tumbleweed.
> Among a few things, the kernel upgraded from 4.7.1 to 4.7.2.

Do you mean it being a kernel regression, or did it happen before?

> After using the laptop all weekend, I suspended the laptop, moved to the
> dock, resumed, and used two external monitors with the lid shut.
> In the afternoon, I suspended, undocked, and resumed in another location. 
> I had no laptop display.  If I suspended, and resumed again, the laptop
> briefly displays the lock screen and then goes blank.  I could plug in an
> external HDMI monitor, and could see my desktop.
> 
> I suspended, and moved back to the dock, resumed, and the external displays
> worked.
> If I suspended, undocked, and resumed, no display on the laptop.

Could you try remote login at this state, and check xrandr output?
(Run "xhost +" beforehand to allow access to the display, and run "export
DISPLAY=:0" before running xrandr.)

Is the external display still recognized as connected?
And what if you run "xrandr --auto" there?

Last but not least, boot with drm.debug=0x0e option, try the procedure to
reproduce the bug, and attach the kernel messages.  It'll show more
information.