Merge tag 'drm-intel-fixes-2018-01-18' of git://anongit.freedesktop.o…

…rg/drm/drm-intel into drm-fixes

Display corruption regression bugfix with both a prep patch and a
follow-up fix

* tag 'drm-intel-fixes-2018-01-18' of git://anongit.freedesktop.org/drm/drm-intel:
  drm/i915: Fix deadlock in i830_disable_pipe()
  drm/i915: Redo plane sanitation during readout
  drm/i915: Add .get_hw_state() method for planes