https://bugs.freedesktop.org/show_bug.cgi?id=93017
--- Comment #3 from Yaroslav Halchenko debian@onerussian.com --- Thank you Michael for your response!
Kernel
according to my irc log on #intel-gfx started to happen with upgrade to 4.2.0-1-amd64, and according to old copy of the journal it was
Oct 25 11:22:54 hopa kernel: Linux version 3.17-1-amd64 (debian-kernel@lists.debian.org) (gcc version 4.8.3 (Debian 4.8.3-13) ) #1 SMP Debian 3.17-1~exp1 (2014-10-14)
before that. bisection I guess will be the measure of last resort -- this laptop is the main workhorse and halt is not 100% reproducible
patch: applied and rebuilding now. Will report as soon as halts again (will do some forceful playful interaction with external displays tomorrow) or if can't trigger the halt. Thanks!