Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

===================================================================
RCS file: /ftp/cvs/cvsroot/src/sys/dev/ic/com.c,v
rcsdiff: /ftp/cvs/cvsroot/src/sys/dev/ic/com.c,v: warning: Unknown phrases like `commitid ...;' are present.
retrieving revision 1.155
retrieving revision 1.156
diff -u -p -r1.155 -r1.156
--- src/sys/dev/ic/com.c	1999/02/28 17:10:52	1.155
+++ src/sys/dev/ic/com.c	1999/03/29 10:01:39	1.156
@@ -1,4 +1,4 @@
-/*	$NetBSD: com.c,v 1.155 1999/02/28 17:10:52 explorer Exp $	*/
+/*	$NetBSD: com.c,v 1.156 1999/03/29 10:01:39 ross Exp $	*/
 
 /*-
  * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
@@ -223,6 +223,10 @@ void	com_kgdb_putc __P((void *, int));
 #define	COM_ISALIVE(sc)	((sc)->enabled != 0 && \
 			 ISSET((sc)->sc_dev.dv_flags, DVF_ACTIVE))
 
+#define	BR	BUS_SPACE_BARRIER_READ
+#define	BW	BUS_SPACE_BARRIER_WRITE
+#define COM_BARRIER(t, h, f) bus_space_barrier((t), (h), 0, COM_NPORTS, (f))
+
 int
 comspeed(speed, frequency)
 	long speed, frequency;
@@ -2170,25 +2174,32 @@ com_common_putc(iot, ioh, c)
 	int c;
 {
 	int s = splserial();
+	int clearirq;
 	u_char stat;
 	int timo;
 
 	/* wait for any pending transmission to finish */
-	timo = 50000;
+	timo = 500;
 	while (!ISSET(stat = bus_space_read_1(iot, ioh, com_lsr), LSR_TXRDY)
 	    && --timo)
-		;
+		delay(100);
 
+	clearirq = ISSET(bus_space_read_1(iot, ioh, com_iir), IIR_NOPEND);
+	COM_BARRIER(iot, ioh, BR | BW);
 	bus_space_write_1(iot, ioh, com_data, c);
+	COM_BARRIER(iot, ioh, BR | BW);
 	/* wait for this transmission to complete */
-	timo = 1500000;
+	timo = 15000;
 	while (!ISSET(stat = bus_space_read_1(iot, ioh, com_lsr), LSR_TXRDY)
 	    && --timo)
-		;
+		delay(100);
 
-	/* clear any interrupts generated by this transmission */
-	stat = bus_space_read_1(iot, ioh, com_iir);
-	splx(s);
+	if(clearirq != 0) {
+		/* clear any interrupts generated by this transmission */
+		(void)bus_space_read_1(iot, ioh, com_iir);
+		COM_BARRIER(iot, ioh, BR | BW);
+		splx(s);
+	}
 }
 
 /*