diff --git a/sys/dev/cy/cy.c b/sys/dev/cy/cy.c
index 50778d5aeb06..53caa3edb661 100644
--- a/sys/dev/cy/cy.c
+++ b/sys/dev/cy/cy.c
@@ -299,9 +299,7 @@ struct com_s {
 	struct termios	lt_out;
 
 	bool_t	do_timestamp;
-	bool_t	do_dcd_timestamp;
 	struct timeval	timestamp;
-	struct timeval	dcd_timestamp;
 
 	u_long	bytes_in;	/* statistics */
 	u_long	bytes_out;
@@ -1283,11 +1281,6 @@ cont:
 			++com->mdm;
 			modem_status = cd_inb(iobase, CD1400_MSVR2, cy_align);
 		if (modem_status != com->last_modem_status) {
-			if (com->do_dcd_timestamp
-			    && !(com->last_modem_status & MSR_DCD)
-			    && modem_status & MSR_DCD)
-				microtime(&com->dcd_timestamp);
-
 			/*
 			 * Schedule high level to handle DCD changes.  Note
 			 * that we don't use the delta bits anywhere.  Some
@@ -1673,10 +1666,6 @@ sioioctl(dev, cmd, data, flag, td)
 		com->do_timestamp = TRUE;
 		*(struct timeval *)data = com->timestamp;
 		break;
-	case TIOCDCDTIMESTAMP:
-		com->do_dcd_timestamp = TRUE;
-		*(struct timeval *)data = com->dcd_timestamp;
-		break;
 	default:
 		splx(s);
 		return (ENOTTY);
diff --git a/sys/dev/digi/digi.h b/sys/dev/digi/digi.h
index 8459d60f1816..a037900cfb8d 100644
--- a/sys/dev/digi/digi.h
+++ b/sys/dev/digi/digi.h
@@ -107,10 +107,6 @@ struct digi_p {
 	struct termios lt_in;		/* should be in struct tty */
 	struct termios lt_out;
 
-	u_int do_timestamp;
-	u_int do_dcd_timestamp;
-	struct timeval dcd_timestamp;
-
 	u_long bytes_in, bytes_out;
 	u_int delta_error_counts[CE_NTYPES];
 	u_long error_counts;
diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c
index 50a0ccbb0329..59c23657374b 100644
--- a/sys/dev/sio/sio.c
+++ b/sys/dev/sio/sio.c
@@ -251,9 +251,7 @@ struct com_s {
 	struct termios	lt_out;
 
 	bool_t	do_timestamp;
-	bool_t	do_dcd_timestamp;
 	struct timeval	timestamp;
-	struct timeval	dcd_timestamp;
 	struct	pps_state pps;
 	int	pps_bit;
 #ifdef ALT_BREAK_TO_DEBUGGER
@@ -1449,7 +1447,6 @@ comhardclose(com)
 	com->poll = FALSE;
 	com->poll_output = FALSE;
 	com->do_timestamp = FALSE;
-	com->do_dcd_timestamp = FALSE;
 	com->pps.ppsparam.mode = 0;
 	sio_setreg(com, com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
 	tp = com->tp;
@@ -1914,11 +1911,6 @@ cont:
 		/* modem status change? (always check before doing output) */
 		modem_status = inb(com->modem_status_port);
 		if (modem_status != com->last_modem_status) {
-			if (com->do_dcd_timestamp
-			    && !(com->last_modem_status & MSR_DCD)
-			    && modem_status & MSR_DCD)
-				microtime(&com->dcd_timestamp);
-
 			/*
 			 * Schedule high level to handle DCD changes.  Note
 			 * that we don't use the delta bits anywhere.  Some
@@ -2160,10 +2152,6 @@ sioioctl(dev, cmd, data, flag, td)
 		com->do_timestamp = TRUE;
 		*(struct timeval *)data = com->timestamp;
 		break;
-	case TIOCDCDTIMESTAMP:
-		com->do_dcd_timestamp = TRUE;
-		*(struct timeval *)data = com->dcd_timestamp;
-		break;
 	default:
 		splx(s);
 		error = pps_ioctl(cmd, data, &com->pps);
diff --git a/sys/pc98/cbus/sio.c b/sys/pc98/cbus/sio.c
index 050804b5c7c7..fedf3d6ed4b2 100644
--- a/sys/pc98/cbus/sio.c
+++ b/sys/pc98/cbus/sio.c
@@ -331,9 +331,7 @@ struct com_s {
 	struct termios	lt_out;
 
 	bool_t	do_timestamp;
-	bool_t	do_dcd_timestamp;
 	struct timeval	timestamp;
-	struct timeval	dcd_timestamp;
 	struct	pps_state pps;
 	int	pps_bit;
 #ifdef ALT_BREAK_TO_DEBUGGER
@@ -2169,7 +2167,6 @@ comhardclose(com)
 	com->poll = FALSE;
 	com->poll_output = FALSE;
 	com->do_timestamp = FALSE;
-	com->do_dcd_timestamp = FALSE;
 	com->pps.ppsparam.mode = 0;
 #ifdef PC98
 	if (IS_8251(com->pc98_if_type))
@@ -2807,11 +2804,6 @@ cont:
 #endif
 		modem_status = inb(com->modem_status_port);
 		if (modem_status != com->last_modem_status) {
-			if (com->do_dcd_timestamp
-			    && !(com->last_modem_status & MSR_DCD)
-			    && modem_status & MSR_DCD)
-				microtime(&com->dcd_timestamp);
-
 			/*
 			 * Schedule high level to handle DCD changes.  Note
 			 * that we don't use the delta bits anywhere.  Some
@@ -3135,10 +3127,6 @@ sioioctl(dev, cmd, data, flag, td)
 		com->do_timestamp = TRUE;
 		*(struct timeval *)data = com->timestamp;
 		break;
-	    case TIOCDCDTIMESTAMP:
-		com->do_dcd_timestamp = TRUE;
-		*(struct timeval *)data = com->dcd_timestamp;
-		break;
 	    default:
 		splx(s);
 		error = pps_ioctl(cmd, data, &com->pps);
@@ -3193,10 +3181,6 @@ sioioctl(dev, cmd, data, flag, td)
 		com->do_timestamp = TRUE;
 		*(struct timeval *)data = com->timestamp;
 		break;
-	case TIOCDCDTIMESTAMP:
-		com->do_dcd_timestamp = TRUE;
-		*(struct timeval *)data = com->dcd_timestamp;
-		break;
 	default:
 		splx(s);
 		error = pps_ioctl(cmd, data, &com->pps);
diff --git a/sys/pc98/pc98/sio.c b/sys/pc98/pc98/sio.c
index 050804b5c7c7..fedf3d6ed4b2 100644
--- a/sys/pc98/pc98/sio.c
+++ b/sys/pc98/pc98/sio.c
@@ -331,9 +331,7 @@ struct com_s {
 	struct termios	lt_out;
 
 	bool_t	do_timestamp;
-	bool_t	do_dcd_timestamp;
 	struct timeval	timestamp;
-	struct timeval	dcd_timestamp;
 	struct	pps_state pps;
 	int	pps_bit;
 #ifdef ALT_BREAK_TO_DEBUGGER
@@ -2169,7 +2167,6 @@ comhardclose(com)
 	com->poll = FALSE;
 	com->poll_output = FALSE;
 	com->do_timestamp = FALSE;
-	com->do_dcd_timestamp = FALSE;
 	com->pps.ppsparam.mode = 0;
 #ifdef PC98
 	if (IS_8251(com->pc98_if_type))
@@ -2807,11 +2804,6 @@ cont:
 #endif
 		modem_status = inb(com->modem_status_port);
 		if (modem_status != com->last_modem_status) {
-			if (com->do_dcd_timestamp
-			    && !(com->last_modem_status & MSR_DCD)
-			    && modem_status & MSR_DCD)
-				microtime(&com->dcd_timestamp);
-
 			/*
 			 * Schedule high level to handle DCD changes.  Note
 			 * that we don't use the delta bits anywhere.  Some
@@ -3135,10 +3127,6 @@ sioioctl(dev, cmd, data, flag, td)
 		com->do_timestamp = TRUE;
 		*(struct timeval *)data = com->timestamp;
 		break;
-	    case TIOCDCDTIMESTAMP:
-		com->do_dcd_timestamp = TRUE;
-		*(struct timeval *)data = com->dcd_timestamp;
-		break;
 	    default:
 		splx(s);
 		error = pps_ioctl(cmd, data, &com->pps);
@@ -3193,10 +3181,6 @@ sioioctl(dev, cmd, data, flag, td)
 		com->do_timestamp = TRUE;
 		*(struct timeval *)data = com->timestamp;
 		break;
-	case TIOCDCDTIMESTAMP:
-		com->do_dcd_timestamp = TRUE;
-		*(struct timeval *)data = com->dcd_timestamp;
-		break;
 	default:
 		splx(s);
 		error = pps_ioctl(cmd, data, &com->pps);
diff --git a/sys/sys/ttycom.h b/sys/sys/ttycom.h
index cfdc9d551c27..a2a7607cb2b6 100644
--- a/sys/sys/ttycom.h
+++ b/sys/sys/ttycom.h
@@ -131,9 +131,7 @@ struct winsize {
 						/* 90-70 ppp; many conflicts */
 #define	TIOCTIMESTAMP	_IOR('t', 89, struct timeval)	/* enable/get timestamp
 						 * of last input event */
-#define	TIOCDCDTIMESTAMP _IOR('t', 88, struct timeval)	/* enable/get timestamp
-						 * of last DCd rise */
-						/* 88 slip; conflicts */
+						/* 88 slip, ppp; conflicts */
 #define	TIOCSDRAINWAIT	_IOW('t', 87, int)	/* set ttywait timeout */
 #define	TIOCGDRAINWAIT	_IOR('t', 86, int)	/* get ttywait timeout */
 						/* 84-80 slip */