This is missing in:
commit 78325f2d27
Author: Ben Widawsky <benjamin.widawsky@intel.com>
Date: Tue Apr 29 14:52:29 2014 -0700
drm/i915: Virtualize the ringbuffer signal func
Looks to me like a rebase side-effect...
Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>