I've just also seen this on 4.3.0-040300rc7-generic, not sure if that's related:
[drm:intel_pipe_update_end [i915]] *ERROR* Atomic update failure on pipe A (start=65757 end=65758)
I've just also seen this on 4.3.0-040300rc7 -generic, not sure if that's related:
[drm:intel_ pipe_update_ end [i915]] *ERROR* Atomic update failure on pipe A (start=65757 end=65758)