This series builds upon the set of fixes previously submitted to move
Armada DRM closer to atomic modeset.  We're nowhere near yet, but this
series helps to get us closer by unifying some of the differences
between the primary and overlay planes.

New features added allows userspace to disable the primary plane if
overlay is full screen and there's nothing obscuring the colorkey -
this saves having to fetch an entire buffer containing nothing but
colorkey when displaying full screen video.

[airlied: fixup for atomic plane helper rename:
a01cb8ba
Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date:   Wed Nov 1 22:16:19 2017 +0200

    drm: Move drm_plane_helper_check_state() into drm_atomic_helper.c
]

* 'drm-armada-devel-4.15' of git://git.armlinux.org.uk/~rmk/linux-arm: (29 commits)
  drm/armada: expand overlay trace entry
  drm/armada: implement primary plane update
  drm/armada: extract register generation from armada_drm_primary_set()
  drm/armada: wait for previous work when moving overlay window
  drm/armada: move overlay plane register update generation
  drm/armada: re-organise overlay register update generation
  drm/armada: disable planes at next blanking period
  drm/armada: avoid work allocation
  drm/armada: allow armada_drm_plane_work_queue() to silently fail
  drm/armada: use drm_plane_helper_check_state()
  drm/armada: only enable HSMOOTH if scaling horizontally
  drm/armada: move writes of LCD_SPU_SRAM_PARA1 under lock
  drm/armada: move regs into armada_plane_work
  drm/armada: move event sending into armada_plane_work
  drm/armada: move fb retirement into armada_plane_work
  drm/armada: move overlay plane work out from under spinlock
  drm/armada: clear plane enable bit when disabling
  drm/armada: clean up armada_drm_crtc_plane_disable()
  drm/armada: allow the primary plane to be disabled
  drm/armada: wait and cancel any pending frame work at disable
  ...