media: uvcvideo: Set media controller entity functions

The media controller core prints a warning when an entity is registered
without a function being set. This affects the uvcvideo driver, as the
warning was added without first addressing the issue in existing
drivers. The problem is harmless, but unnecessarily worries users. Fix
it by mapping UVC entity types to MC entity functions as accurately as
possible using the existing functions.

Fixes: b50bde4e47 ("[media] v4l2-subdev: use MEDIA_ENT_T_UNKNOWN for new subdevs")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/usb/uvc/uvc_entity.c

@@ -73,10 +73,45 @@ static int uvc_mc_init_entity(struct uvc_video_chain *chain,
 	int ret;
 
 	if (UVC_ENTITY_TYPE(entity) != UVC_TT_STREAMING) {
+		u32 function;
+
 		v4l2_subdev_init(&entity->subdev, &uvc_subdev_ops);
 		strscpy(entity->subdev.name, entity->name,
 			sizeof(entity->subdev.name));
 
+		switch (UVC_ENTITY_TYPE(entity)) {
+		case UVC_VC_SELECTOR_UNIT:
+			function = MEDIA_ENT_F_VID_MUX;
+			break;
+		case UVC_VC_PROCESSING_UNIT:
+		case UVC_VC_EXTENSION_UNIT:
+			/* For lack of a better option. */
+			function = MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER;
+			break;
+		case UVC_COMPOSITE_CONNECTOR:
+		case UVC_COMPONENT_CONNECTOR:
+			function = MEDIA_ENT_F_CONN_COMPOSITE;
+			break;
+		case UVC_SVIDEO_CONNECTOR:
+			function = MEDIA_ENT_F_CONN_SVIDEO;
+			break;
+		case UVC_ITT_CAMERA:
+			function = MEDIA_ENT_F_CAM_SENSOR;
+			break;
+		case UVC_TT_VENDOR_SPECIFIC:
+		case UVC_ITT_VENDOR_SPECIFIC:
+		case UVC_ITT_MEDIA_TRANSPORT_INPUT:
+		case UVC_OTT_VENDOR_SPECIFIC:
+		case UVC_OTT_DISPLAY:
+		case UVC_OTT_MEDIA_TRANSPORT_OUTPUT:
+		case UVC_EXTERNAL_VENDOR_SPECIFIC:
+		default:
+			function = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
+			break;
+		}
+
+		entity->subdev.entity.function = function;
+
 		ret = media_entity_pads_init(&entity->subdev.entity,
 					entity->num_pads, entity->pads);