diff --git a/Documentation/driver-api/serial/serial-rs485.rst b/Documentation/driver-api/serial/serial-rs485.rst
index 6bc824f948f9..00b5d333acba 100644
--- a/Documentation/driver-api/serial/serial-rs485.rst
+++ b/Documentation/driver-api/serial/serial-rs485.rst
@@ -38,10 +38,14 @@ RS485 Serial Communications
    the values given by the device tree.
 
    Any driver for devices capable of working both as RS232 and RS485 should
-   implement the rs485_config callback in the uart_port structure. The
-   serial_core calls rs485_config to do the device specific part in response
-   to TIOCSRS485 and TIOCGRS485 ioctls (see below). The rs485_config callback
-   receives a pointer to struct serial_rs485.
+   implement the rs485_config callback and provide rs485_supported in the
+   uart_port structure. The serial core calls rs485_config to do the device
+   specific part in response to TIOCSRS485 ioctl (see below). The rs485_config
+   callback receives a pointer to a sanitizated serial_rs485 structure. The
+   serial_rs485 userspace provides is sanitized before calling rs485_config
+   using rs485_supported that indicates what RS485 features the driver supports
+   for the uart_port. TIOCGRS485 ioctl can be used to read back the
+   serial_rs485 structure matching to the current configuration.
 
 4. Usage from user-level
 ========================
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 44a50158552d..f0d7b3d20731 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1278,36 +1278,61 @@ static int uart_get_icount(struct tty_struct *tty,
 
 static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs485 *rs485)
 {
+	u32 supported_flags = port->rs485_supported->flags;
+
 	/* pick sane settings if the user hasn't */
-	if (!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
+	if ((supported_flags & (SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND)) &&
+	    !(rs485->flags & SER_RS485_RTS_ON_SEND) ==
 	    !(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
 		dev_warn_ratelimited(port->dev,
 			"%s (%d): invalid RTS setting, using RTS_ON_SEND instead\n",
 			port->name, port->line);
 		rs485->flags |= SER_RS485_RTS_ON_SEND;
 		rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
+		supported_flags |= SER_RS485_RTS_ON_SEND|SER_RS485_RTS_AFTER_SEND;
 	}
 
-	if (rs485->delay_rts_before_send > RS485_MAX_RTS_DELAY) {
+	if (!port->rs485_supported->delay_rts_before_send) {
+		if (rs485->delay_rts_before_send) {
+			dev_warn_ratelimited(port->dev,
+				"%s (%d): RTS delay before sending not supported\n",
+				port->name, port->line);
+		}
+		rs485->delay_rts_before_send = 0;
+	} else if (rs485->delay_rts_before_send > RS485_MAX_RTS_DELAY) {
 		rs485->delay_rts_before_send = RS485_MAX_RTS_DELAY;
 		dev_warn_ratelimited(port->dev,
 			"%s (%d): RTS delay before sending clamped to %u ms\n",
 			port->name, port->line, rs485->delay_rts_before_send);
 	}
 
-	if (rs485->delay_rts_after_send > RS485_MAX_RTS_DELAY) {
+	if (!port->rs485_supported->delay_rts_after_send) {
+		if (rs485->delay_rts_after_send) {
+			dev_warn_ratelimited(port->dev,
+				"%s (%d): RTS delay after sending not supported\n",
+				port->name, port->line);
+		}
+		rs485->delay_rts_after_send = 0;
+	} else if (rs485->delay_rts_after_send > RS485_MAX_RTS_DELAY) {
 		rs485->delay_rts_after_send = RS485_MAX_RTS_DELAY;
 		dev_warn_ratelimited(port->dev,
 			"%s (%d): RTS delay after sending clamped to %u ms\n",
 			port->name, port->line, rs485->delay_rts_after_send);
 	}
+
+	rs485->flags &= supported_flags;
+
 	/* Return clean padding area to userspace */
 	memset(rs485->padding, 0, sizeof(rs485->padding));
 }
 
 int uart_rs485_config(struct uart_port *port)
 {
-	return port->rs485_config(port, &port->rs485);
+	struct serial_rs485 *rs485 = &port->rs485;
+
+	uart_sanitize_serial_rs485(port, rs485);
+
+	return port->rs485_config(port, rs485);
 }
 EXPORT_SYMBOL_GPL(uart_rs485_config);