diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 5b4721bd70f0..d24270fe3cbe 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1076,6 +1076,11 @@ static int lpuart_config_rs485(struct uart_port *port,
 		~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
 	writeb(modem, sport->port.membase + UARTMODEM);
 
+	/* clear unsupported configurations */
+	rs485->delay_rts_before_send = 0;
+	rs485->delay_rts_after_send = 0;
+	rs485->flags &= ~SER_RS485_RX_DURING_TX;
+
 	if (rs485->flags & SER_RS485_ENABLED) {
 		/* Enable auto RS-485 RTS mode */
 		modem |= UARTMODEM_TXRTSE;