Comment # 2 on bug 102338 from Takashi Iwai

Now we hit this on openSUSE Tumbleweed, 4.12.9 & later, too.
  https://bugs.freedesktop.org/show_bug.cgi?id=102338

I quickly bisected and it pointed to the commit
3538e80a869be74764ae7db484b371894f04d0f8
    drm: qxl: Atomic phase 1: Implement mode_set_nofb