PIPE_START_VBLANK_INTERRUPT_ENABLE  526 drivers/gpu/drm/gma500/psb_intel_reg.h #define PIPE_START_VBLANK_INTERRUPT_ENABLE	(1UL << 18)
PIPE_START_VBLANK_INTERRUPT_ENABLE 5697 drivers/gpu/drm/i915/i915_reg.h #define   PIPE_START_VBLANK_INTERRUPT_ENABLE	(1UL << 18) /* 965 or later */