USB: serial: cp210x: fix GPIO in autosuspend

Current GPIO code in cp210x fails to take USB autosuspend into account,
making it practically impossible to use GPIOs with autosuspend enabled
without user configuration. Fix this like for ftdi_sio in a previous patch.
Tested on a CP2102N.
Signed-off-by: Karoly Pados <pados@pados.hu>
Fixes: cf5276ce ("USB: serial: cp210x: Adding GPIO support for CP2105")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/cp210x.c

@@ -1370,8 +1370,13 @@ static int cp210x_gpio_get(struct gpio_chip *gc, unsigned int gpio)
 	if (priv->partnum == CP210X_PARTNUM_CP2105)
 		req_type = REQTYPE_INTERFACE_TO_HOST;
 
+	result = usb_autopm_get_interface(serial->interface);
+	if (result)
+		return result;
+
 	result = cp210x_read_vendor_block(serial, req_type,
 					  CP210X_READ_LATCH, &buf, sizeof(buf));
+	usb_autopm_put_interface(serial->interface);
 	if (result < 0)
 		return result;
 
@@ -1392,6 +1397,10 @@ static void cp210x_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
 
 	buf.mask = BIT(gpio);
 
+	result = usb_autopm_get_interface(serial->interface);
+	if (result)
+		goto out;
+
 	if (priv->partnum == CP210X_PARTNUM_CP2105) {
 		result = cp210x_write_vendor_block(serial,
 						   REQTYPE_HOST_TO_INTERFACE,
@@ -1409,6 +1418,8 @@ static void cp210x_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
 					 NULL, 0, USB_CTRL_SET_TIMEOUT);
 	}
 
+	usb_autopm_put_interface(serial->interface);
+out:
 	if (result < 0) {
 		dev_err(&serial->interface->dev, "failed to set GPIO value: %d\n",
 				result);