__get_vblank_counter
cur_vblank = __get_vblank_counter(dev, pipe);
} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
cur_vblank = __get_vblank_counter(dev, pipe);
} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);
cur_vblank = __get_vblank_counter(dev, pipe);
} while (cur_vblank != __get_vblank_counter(dev, pipe) && --count > 0);