intel_ring_wrap
request->ring->head = intel_ring_wrap(request->ring, request->postfix);
rq->tail = intel_ring_wrap(rq->ring, rq->wa_tail - WA_TAIL_BYTES);
rq->ring->head = intel_ring_wrap(rq->ring, rq->head);
return intel_ring_wrap(rq->ring, offset);