[media] v4l2-device: Register entity before calling subdev's registered ops

Registering a V4L2 sub-device includes, among other things, registering
the related media entity and calling the sub-device's registered op. Since
patch "media: convert links from array to list", creating a link between
two pads requires registering the entity first. If the registered() op
involves link creation, the link list head will not be initialised before
it is used.

Resolve this by first registering the entity, then calling its
registered() op.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/v4l2-core/v4l2-device.c

@@ -180,26 +180,26 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 		return -ENODEV;
 
 	sd->v4l2_dev = v4l2_dev;
-	if (sd->internal_ops && sd->internal_ops->registered) {
-		err = sd->internal_ops->registered(sd);
-		if (err)
-			goto error_module;
-	}
-
 	/* This just returns 0 if either of the two args is NULL */
 	err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler, NULL);
 	if (err)
-		goto error_unregister;
+		goto error_module;
 
 #if defined(CONFIG_MEDIA_CONTROLLER)
 	/* Register the entity. */
 	if (v4l2_dev->mdev) {
 		err = media_device_register_entity(v4l2_dev->mdev, entity);
 		if (err < 0)
-			goto error_unregister;
+			goto error_module;
 	}
 #endif
 
+	if (sd->internal_ops && sd->internal_ops->registered) {
+		err = sd->internal_ops->registered(sd);
+		if (err)
+			goto error_unregister;
+	}
+
 	spin_lock(&v4l2_dev->lock);
 	list_add_tail(&sd->list, &v4l2_dev->subdevs);
 	spin_unlock(&v4l2_dev->lock);
@@ -207,8 +207,9 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 	return 0;
 
 error_unregister:
-	if (sd->internal_ops && sd->internal_ops->unregistered)
-		sd->internal_ops->unregistered(sd);
+#if defined(CONFIG_MEDIA_CONTROLLER)
+	media_device_unregister_entity(entity);
+#endif
 error_module:
 	if (!sd->owner_v4l2_dev)
 		module_put(sd->owner);