IMXUART_RX_IBUF_OVERFLOWED
if (ISSET(sc->sc_rx_flags, IMXUART_RX_IBUF_OVERFLOWED)) {
CLR(sc->sc_rx_flags, IMXUART_RX_IBUF_OVERFLOWED);
sc->sc_rx_flags |= IMXUART_RX_IBUF_OVERFLOWED;
IMXUART_RX_IBUF_BLOCKED|IMXUART_RX_IBUF_OVERFLOWED)