drm_vblank_count
u64 drm_vblank_count(struct drm_device *dev, unsigned int pipe);
last = drm_vblank_count(dev, pipe);
last != drm_vblank_count(dev, pipe),
seq = drm_vblank_count(dev, pipe);
drm_vblank_passed(drm_vblank_count(dev, pipe), req_seq) ||
vblank = drm_vblank_count(dev, pipe);
return drm_vblank_count(crtc->dev, drm_crtc_index(crtc));
cur_vbl = drm_vblank_count(dev, vblank->pipe);