diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 92a8b263735a6..9e0c63676f0a4 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -341,13 +341,37 @@ static u_int atmel_tx_empty(struct uart_port *port)
 static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 {
 	unsigned int control = 0;
-	unsigned int mode;
+	unsigned int mode = UART_GET_MR(port);
+	unsigned int rts_paused, rts_ready;
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
+	/* override mode to RS485 if needed, otherwise keep the current mode */
+	if (port->rs485.flags & SER_RS485_ENABLED) {
+		if ((port->rs485.delay_rts_after_send) > 0)
+			UART_PUT_TTGR(port, port->rs485.delay_rts_after_send);
+		mode &= ~ATMEL_US_USMODE;
+		mode |= ATMEL_US_USMODE_RS485;
+	}
+
+	/* set the RTS line state according to the mode */
+	if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) {
+		/* force RTS line to high level */
+		rts_paused = ATMEL_US_RTSEN;
+
+		/* give the control of the RTS line back to the hardware */
+		rts_ready = ATMEL_US_RTSDIS;
+	} else {
+		/* force RTS line to high level */
+		rts_paused = ATMEL_US_RTSDIS;
+
+		/* force RTS line to low level */
+		rts_ready = ATMEL_US_RTSEN;
+	}
+
 	if (mctrl & TIOCM_RTS)
-		control |= ATMEL_US_RTSEN;
+		control |= rts_ready;
 	else
-		control |= ATMEL_US_RTSDIS;
+		control |= rts_paused;
 
 	if (mctrl & TIOCM_DTR)
 		control |= ATMEL_US_DTREN;
@@ -359,23 +383,12 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
 	mctrl_gpio_set(atmel_port->gpios, mctrl);
 
 	/* Local loopback mode? */
-	mode = UART_GET_MR(port) & ~ATMEL_US_CHMODE;
+	mode &= ~ATMEL_US_CHMODE;
 	if (mctrl & TIOCM_LOOP)
 		mode |= ATMEL_US_CHMODE_LOC_LOOP;
 	else
 		mode |= ATMEL_US_CHMODE_NORMAL;
 
-	/* Resetting serial mode to RS232 (0x0) */
-	mode &= ~ATMEL_US_USMODE;
-
-	if (port->rs485.flags & SER_RS485_ENABLED) {
-		dev_dbg(port->dev, "Setting UART to RS485\n");
-		if ((port->rs485.delay_rts_after_send) > 0)
-			UART_PUT_TTGR(port, port->rs485.delay_rts_after_send);
-		mode |= ATMEL_US_USMODE_RS485;
-	} else {
-		dev_dbg(port->dev, "Setting UART to RS232\n");
-	}
 	UART_PUT_MR(port, mode);
 }
 
@@ -1921,12 +1934,14 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 			      struct ktermios *old)
 {
 	unsigned long flags;
-	unsigned int mode, imr, quot, baud;
+	unsigned int old_mode, mode, imr, quot, baud;
+
+	/* save the current mode register */
+	mode = old_mode = UART_GET_MR(port);
 
-	/* Get current mode register */
-	mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
-					| ATMEL_US_NBSTOP | ATMEL_US_PAR
-					| ATMEL_US_USMODE);
+	/* reset the mode, clock divisor, parity, stop bits and data size */
+	mode &= ~(ATMEL_US_USCLKS | ATMEL_US_CHRL | ATMEL_US_NBSTOP |
+		  ATMEL_US_PAR | ATMEL_US_USMODE);
 
 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
 	quot = uart_get_divisor(port, baud);
@@ -1971,12 +1986,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 	} else
 		mode |= ATMEL_US_PAR_NONE;
 
-	/* hardware handshake (RTS/CTS) */
-	if (termios->c_cflag & CRTSCTS)
-		mode |= ATMEL_US_USMODE_HWHS;
-	else
-		mode |= ATMEL_US_USMODE_NORMAL;
-
 	spin_lock_irqsave(&port->lock, flags);
 
 	port->read_status_mask = ATMEL_US_OVRE;
@@ -2020,18 +2029,40 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* disable receiver and transmitter */
 	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
 
-	/* Resetting serial mode to RS232 (0x0) */
-	mode &= ~ATMEL_US_USMODE;
-
+	/* mode */
 	if (port->rs485.flags & SER_RS485_ENABLED) {
 		if ((port->rs485.delay_rts_after_send) > 0)
 			UART_PUT_TTGR(port, port->rs485.delay_rts_after_send);
 		mode |= ATMEL_US_USMODE_RS485;
+	} else if (termios->c_cflag & CRTSCTS) {
+		/* RS232 with hardware handshake (RTS/CTS) */
+		mode |= ATMEL_US_USMODE_HWHS;
+	} else {
+		/* RS232 without hadware handshake */
+		mode |= ATMEL_US_USMODE_NORMAL;
 	}
 
-	/* set the parity, stop bits and data size */
+	/* set the mode, clock divisor, parity, stop bits and data size */
 	UART_PUT_MR(port, mode);
 
+	/*
+	 * when switching the mode, set the RTS line state according to the
+	 * new mode, otherwise keep the former state
+	 */
+	if ((old_mode & ATMEL_US_USMODE) != (mode & ATMEL_US_USMODE)) {
+		unsigned int rts_state;
+
+		if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) {
+			/* let the hardware control the RTS line */
+			rts_state = ATMEL_US_RTSDIS;
+		} else {
+			/* force RTS line to low level */
+			rts_state = ATMEL_US_RTSEN;
+		}
+
+		UART_PUT_CR(port, rts_state);
+	}
+
 	/* set the baud rate */
 	UART_PUT_BRGR(port, quot);
 	UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);