MCS7840_UART_REG_IER
if (umcs7840_set_UART_reg_sync(sc, pn, MCS7840_UART_REG_IER, 0))
if (umcs7840_set_UART_reg_sync(sc, pn, MCS7840_UART_REG_IER,
umcs7840_set_UART_reg_sync(sc, pn, MCS7840_UART_REG_IER, 0);