diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 40d4895fd208..b8d05a7dfcf9 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1504,18 +1504,19 @@ static void start_hrtimer_ms(struct hrtimer *hrt, unsigned long msec)
 	hrtimer_start(hrt, ms_to_ktime(msec), HRTIMER_MODE_REL);
 }
 
-static void __stop_tx_rs485(struct uart_8250_port *p)
+static void __stop_tx_rs485(struct uart_8250_port *p, u64 stop_delay)
 {
 	struct uart_8250_em485 *em485 = p->em485;
 
+	stop_delay += (u64)p->port.rs485.delay_rts_after_send * NSEC_PER_MSEC;
+
 	/*
 	 * rs485_stop_tx() is going to set RTS according to config
 	 * AND flush RX FIFO if required.
 	 */
-	if (p->port.rs485.delay_rts_after_send > 0) {
+	if (stop_delay > 0) {
 		em485->active_timer = &em485->stop_tx_timer;
-		start_hrtimer_ms(&em485->stop_tx_timer,
-				   p->port.rs485.delay_rts_after_send);
+		hrtimer_start(&em485->stop_tx_timer, ns_to_ktime(stop_delay), HRTIMER_MODE_REL);
 	} else {
 		p->rs485_stop_tx(p);
 		em485->active_timer = NULL;
@@ -1535,16 +1536,32 @@ static inline void __stop_tx(struct uart_8250_port *p)
 
 	if (em485) {
 		unsigned char lsr = serial_in(p, UART_LSR);
+		u64 stop_delay = 0;
+
+		if (!(lsr & UART_LSR_THRE))
+			return;
 		/*
 		 * To provide required timeing and allow FIFO transfer,
 		 * __stop_tx_rs485() must be called only when both FIFO and
-		 * shift register are empty. It is for device driver to enable
-		 * interrupt on TEMT.
+		 * shift register are empty. The device driver should either
+		 * enable interrupt on TEMT or set UART_CAP_NOTEMT that will
+		 * enlarge stop_tx_timer by the tx time of one frame to cover
+		 * for emptying of the shift register.
 		 */
-		if ((lsr & BOTH_EMPTY) != BOTH_EMPTY)
-			return;
+		if (!(lsr & UART_LSR_TEMT)) {
+			if (!(p->capabilities & UART_CAP_NOTEMT))
+				return;
+			/*
+			 * RTS might get deasserted too early with the normal
+			 * frame timing formula. It seems to suggest THRE might
+			 * get asserted already during tx of the stop bit
+			 * rather than after it is fully sent.
+			 * Roughly estimate 1 extra bit here with / 7.
+			 */
+			stop_delay = p->port.frame_time + DIV_ROUND_UP(p->port.frame_time, 7);
+		}
 
-		__stop_tx_rs485(p);
+		__stop_tx_rs485(p, stop_delay);
 	}
 	__do_stop_tx(p);
 }