diff --git a/drivers/char/nozomi.c b/drivers/char/nozomi.c
index 584910ff725eaefe7e11826d2e562654d835f04d..a3f32a15fde4196ce889b02be3cb2ada16b16d12 100644
--- a/drivers/char/nozomi.c
+++ b/drivers/char/nozomi.c
@@ -853,8 +853,6 @@ static int receive_data(enum port_type index, struct nozomi *dc)
 		goto put;
 	}
 
-	tty_buffer_request_room(tty, size);
-
 	while (size > 0) {
 		read_mem32((u32 *) buf, addr + offset, RECEIVE_BUF_MAX);
 
diff --git a/drivers/char/serial167.c b/drivers/char/serial167.c
index 452370af95def5a352dd4753107ce3fd4154fb93..986aa606a6b6fe9084762162243f991a05565bab 100644
--- a/drivers/char/serial167.c
+++ b/drivers/char/serial167.c
@@ -658,8 +658,7 @@ static irqreturn_t cd2401_rx_interrupt(int irq, void *dev_id)
 			info->mon.char_max = char_count;
 		info->mon.char_last = char_count;
 #endif
-		len = tty_buffer_request_room(tty, char_count);
-		while (len--) {
+		while (char_count--) {
 			data = base_addr[CyRDR];
 			tty_insert_flip_char(tty, data, TTY_NORMAL);
 #ifdef CYCLOM_16Y_HACK
diff --git a/drivers/char/specialix.c b/drivers/char/specialix.c
index 268e17f9ec3f50c4586607bb0dd59e76442f3bee..07ac14d949ce2f12dc94ab6e3b3c0a7ae3a32931 100644
--- a/drivers/char/specialix.c
+++ b/drivers/char/specialix.c
@@ -646,8 +646,6 @@ static void sx_receive(struct specialix_board *bp)
 	dprintk(SX_DEBUG_RX, "port: %p: count: %d\n", port, count);
 	port->hits[count > 8 ? 9 : count]++;
 
-	tty_buffer_request_room(tty, count);
-
 	while (count--)
 		tty_insert_flip_char(tty, sx_in(bp, CD186x_RDR), TTY_NORMAL);
 	tty_flip_buffer_push(tty);
diff --git a/drivers/serial/icom.c b/drivers/serial/icom.c
index 6e715b78d7a6c2250bf91e89839934857b8ee6a5..53a46822705621ec0f776340381d94c672655e69 100644
--- a/drivers/serial/icom.c
+++ b/drivers/serial/icom.c
@@ -751,7 +751,6 @@ static void recv_interrupt(u16 port_int_reg, struct icom_port *icom_port)
 		trace(icom_port, "FID_STATUS", status);
 		count = cpu_to_le16(icom_port->statStg->rcv[rcv_buff].leLength);
 
-                count = tty_buffer_request_room(tty, count);
 		trace(icom_port, "RCV_COUNT", count);
 
 		trace(icom_port, "REAL_COUNT", count);
diff --git a/drivers/serial/ioc3_serial.c b/drivers/serial/ioc3_serial.c
index 85dc0410ac1a8d3f2bed7a08f8078f23b4de57cd..23ba6b40b3ac4ac9d62f12c0ff2b55c5cd403a5c 100644
--- a/drivers/serial/ioc3_serial.c
+++ b/drivers/serial/ioc3_serial.c
@@ -1411,8 +1411,7 @@ static int receive_chars(struct uart_port *the_port)
 	read_count = do_read(the_port, ch, MAX_CHARS);
 	if (read_count > 0) {
 		flip = 1;
-		read_room = tty_buffer_request_room(tty, read_count);
-		tty_insert_flip_string(tty, ch, read_room);
+		read_room = tty_insert_flip_string(tty, ch, read_count);
 		the_port->icount.rx += read_count;
 	}
 	spin_unlock_irqrestore(&the_port->lock, pflags);