intel_ring_wait_for_space
ret = intel_ring_wait_for_space(ce->ring, MIN_SPACE_FOR_ADD_REQUEST);
ret = intel_ring_wait_for_space(request->ring, request->reserved_space);
ret = intel_ring_wait_for_space(request->ring, request->reserved_space);
int intel_ring_wait_for_space(struct intel_ring *ring, unsigned int bytes);