This is only happening on one of the bdw machines, so likely something specific to that setup. Blocks modeset work in general.
Fixed with commit 97e5ed1111dcc5300a0f59a55248cd243937a8ab Author: Daniel Vetter <daniel.vetter@ffwll.ch> Date: Fri Oct 23 10:56:12 2015 +0200 drm/i915: shut up gen8+ SDE irq dmesg noise
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