Comment # 8 on bug 91333 from Mark Cave-Ayland

Apologies for jumping in on another bug report, however this sounds exactly
like the problem I've been struggling with for years on my Lenovo T420s:

https://bugs.freedesktop.org/show_bug.cgi?id=56615

I see the same symptoms in that the kernel "hangs" with an external DisplayPort
connected in discrete mode when trying to use the internal LVDS with the
external monitor. It seems the message I get in the kernel log is similar too:

nouveau E[   PDISP][0000:01:00.0] chid 1 mthd 0x0080 data 0x00000000 0x00005080
0x0000000