https://bugs.freedesktop.org/show_bug.cgi?id=97025
--- Comment #8 from Bernd Steinhauser linux@bernd-steinhauser.de --- I noticed that those two lines coincident with a certain event I can trigger: Switching the DP-0 display off (an Eizo EV2455). This leads to a disconnect of the DP connection and that leads (somehow) to the quoted messages about the failed vblank. (I'm not sure if the disconnect is actually a bug in the kernel (as it's a DP1.2 display) or if it's my hardware/mainboard/gpu too old.)
However, this disconnect does not lead straight to the freeze. And so far I haven't seen the bug directly after a DP disconnect, but just at some random point.