Comment 11 for bug 1432405

(In reply to Sitsofe Wheeler from comment #2)
> Sadly that kernel doesn't boot at all - just an empty black screen.

Meh. What if you cherry pick

commit f9b61ff6bce9a44555324b29e593fdffc9a115bc
Author: Daniel Vetter <email address hidden>
Date: Wed Jan 7 13:54:39 2015 +0100

    drm/i915: Push vblank enable/disable past encoder->enable/disable

on top of v3.19?