Index: dev/uart/uart_dev_ns8250.c
===================================================================
--- dev/uart/uart_dev_ns8250.c	(revision 247078)
+++ dev/uart/uart_dev_ns8250.c	(working copy)
@@ -65,6 +65,8 @@
 			(void)uart_getreg(bas, REG_DATA);
 		else if (iir == IIR_MLSC)
 			(void)uart_getreg(bas, REG_MSR);
+		else if (iir == IIR_BUSY)
+			(void)uart_getreg(bas, 31);
 		uart_barrier(bas);
 		iir = uart_getreg(bas, REG_IIR);
 	}
@@ -592,10 +594,18 @@
 	bas = &sc->sc_bas;
 	uart_lock(sc->sc_hwmtx);
 	iir = uart_getreg(bas, REG_IIR);
+
+	if ((iir & IIR_BUSY) == IIR_BUSY) {
+		(void)uart_getreg(bas, 31);
+		uart_unlock(sc->sc_hwmtx);
+		return (0);
+	}
+
 	if (iir & IIR_NOPEND) {
 		uart_unlock(sc->sc_hwmtx);
 		return (0);
 	}
+
 	ipend = 0;
 	if (iir & IIR_RXRDY) {
 		lsr = uart_getreg(bas, REG_LSR);