media: uvcvideo: Fix deferred probing error

uvc_gpio_parse() can return -EPROBE_DEFER when the GPIOs it depends on
have not yet been probed. This return code should be propagated to the
caller of uvc_probe() to ensure that probing is retried when the required
GPIOs become available.

Currently, this error code is incorrectly converted to -ENODEV,
causing some internal cameras to be ignored.

This commit fixes this issue by propagating the -EPROBE_DEFER error.

Cc: [e-mail]
Fixes: 2886477ff987 ("media: uvcvideo: Implement UVC_EXT_GPIO_UNIT")
Reviewed-by: Douglas Anderson <[e-mail]>
Signed-off-by: Ricardo Ribalda <[e-mail]>
Message-ID: <[e-mail]>
Reviewed-by: Hans de Goede <[e-mail]>
Signed-off-by: Hans de Goede <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/usb/uvc/uvc_driver.c

···
 #endif
 
 	/* Parse the Video Class control descriptor. */
-	if (uvc_parse_control(dev) < 0) {
+	ret = uvc_parse_control(dev);
+	if (ret < 0) {
+		ret = -ENODEV;
 		uvc_dbg(dev, PROBE, "Unable to parse UVC descriptors\n");
 		goto error;
 	}
 
 	/* Parse the associated GPIOs. */
-	if (uvc_gpio_parse(dev) < 0) {
+	ret = uvc_gpio_parse(dev);
+	if (ret < 0) {
 		uvc_dbg(dev, PROBE, "Unable to parse UVC GPIOs\n");
 		goto error;
 	}
···
 	}
 
 	/* Register the V4L2 device. */
-	if (v4l2_device_register(&intf->dev, &dev->vdev) < 0)
+	ret = v4l2_device_register(&intf->dev, &dev->vdev);
+	if (ret < 0)
 		goto error;
 
 	/* Scan the device for video chains. */
-	if (uvc_scan_device(dev) < 0)
+	if (uvc_scan_device(dev) < 0) {
+		ret = -ENODEV;
 		goto error;
+	}
 
 	/* Initialize controls. */
-	if (uvc_ctrl_init_device(dev) < 0)
+	if (uvc_ctrl_init_device(dev) < 0) {
+		ret = -ENODEV;
 		goto error;
+	}
 
 	/* Register video device nodes. */
-	if (uvc_register_chains(dev) < 0)
+	if (uvc_register_chains(dev) < 0) {
+		ret = -ENODEV;
 		goto error;
+	}
 
 #ifdef CONFIG_MEDIA_CONTROLLER
 	/* Register the media device node */
-	if (media_device_register(&dev->mdev) < 0)
+	ret = media_device_register(&dev->mdev);
+	if (ret < 0)
 		goto error;
 #endif
 	/* Save our data pointer in the interface data. */
···
 error:
 	uvc_unregister_video(dev);
 	kref_put(&dev->ref, uvc_delete);
-	return -ENODEV;
+	return ret;
 }
 
 static void uvc_disconnect(struct usb_interface *intf)