TI_RETURN_RING_CNT
rcb->ti_max_len = TI_RETURN_RING_CNT;
TI_INC(sc->ti_rx_saved_considx, TI_RETURN_RING_CNT);
#define TI_RX_RETURN_RING_SZ (sizeof(struct ti_rx_desc) * TI_RETURN_RING_CNT)