media: uvcvideo: Set unique entity name based in type

All the entities must have a unique name. We can have a descriptive and
unique name by appending the function to their terminal link.

This is even resilient to multi chain devices.

Fixes v4l2-compliance:
Media Controller ioctls:
     fail: v4l2-test-media.cpp(205): v2_entity_names_set.find(key) != v2_entity_names_set.end()
   test MEDIA_IOC_G_TOPOLOGY: FAIL
     fail: v4l2-test-media.cpp(394): num_data_links != num_links
   test MEDIA_IOC_ENUM_ENTITIES/LINKS: FAIL

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
index 058d28a..8efbde9 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -2193,6 +2193,7 @@
 			      const struct v4l2_file_operations *fops,
 			      const struct v4l2_ioctl_ops *ioctl_ops)
 {
+	const char __maybe_unused *name;
 	int ret;
 
 	/* Initialize the video buffers queue. */
@@ -2221,17 +2222,29 @@
 	case V4L2_BUF_TYPE_VIDEO_CAPTURE:
 	default:
 		vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
+		name = "Video Capture";
 		break;
 	case V4L2_BUF_TYPE_VIDEO_OUTPUT:
 		vdev->device_caps = V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_STREAMING;
+		name = "Video Output";
 		break;
 	case V4L2_BUF_TYPE_META_CAPTURE:
 		vdev->device_caps = V4L2_CAP_META_CAPTURE | V4L2_CAP_STREAMING;
+		name = "Metadata";
 		break;
 	}
 
+	/*
+	 * Many userspace applications identify the device with vdev->name, so
+	 * we cannot change its name for its function.
+	 */
 	strscpy(vdev->name, dev->name, sizeof(vdev->name));
 
+#if defined(CONFIG_MEDIA_CONTROLLER)
+	vdev->entity.name = devm_kasprintf(&stream->intf->dev, GFP_KERNEL,
+				"%s %u", name, stream->header.bTerminalLink);
+#endif
+
 	/*
 	 * Set the driver data before calling video_register_device, otherwise
 	 * the file open() handler might race us.