diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index e4d7fbd7e4e7..242b5776648a 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1789,20 +1789,24 @@ static int ftdi_8u2232c_probe(struct usb_serial *serial)
 }
 
 /*
- * First and second port on STMCLiteadaptors is reserved for JTAG interface
- * and the forth port for pio
+ * First two ports on JTAG adaptors using an FT4232 such as STMicroelectronics's
+ * ST Micro Connect Lite are reserved for JTAG or other non-UART interfaces and
+ * can be accessed from userspace.
+ * The next two ports are enabled as UARTs by default, where port 2 is
+ * a conventional RS-232 UART.
  */
 static int ftdi_stmclite_probe(struct usb_serial *serial)
 {
 	struct usb_device *udev = serial->dev;
 	struct usb_interface *interface = serial->interface;
 
-	if (interface == udev->actconfig->interface[2])
-		return 0;
+	if (interface == udev->actconfig->interface[0] ||
+	    interface == udev->actconfig->interface[1]) {
+		dev_info(&udev->dev, "Ignoring serial port reserved for JTAG\n");
+		return -ENODEV;
+	}
 
-	dev_info(&udev->dev, "Ignoring serial port reserved for JTAG\n");
-
-	return -ENODEV;
+	return 0;
 }
 
 /*