media: rcar-vin: remove unneeded locking in async callbacks

The locking implemented in the async notifier callbacks are unnecessary
as the global list_lock in v4l2-async.c is held whenever one of the
callbacks are called.

The locking in itself is not harmful however it produces a LOCKDEP
warning between the global v4l2-async list_lock and the rcar-vin local
locking schema. Remove the rcar-vin locking for the async callbacks to
reduce complexity and silent the false LOCKDEP warning.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/rcar-vin/rcar-core.c

@@ -542,9 +542,7 @@ static void rvin_parallel_notify_unbind(struct v4l2_async_notifier *notifier,
 
 	vin_dbg(vin, "unbind parallel subdev %s\n", subdev->name);
 
-	mutex_lock(&vin->lock);
 	rvin_parallel_subdevice_detach(vin);
-	mutex_unlock(&vin->lock);
 }
 
 static int rvin_parallel_notify_bound(struct v4l2_async_notifier *notifier,
@@ -554,9 +552,7 @@ static int rvin_parallel_notify_bound(struct v4l2_async_notifier *notifier,
 	struct rvin_dev *vin = v4l2_dev_to_vin(notifier->v4l2_dev);
 	int ret;
 
-	mutex_lock(&vin->lock);
 	ret = rvin_parallel_subdevice_attach(vin, subdev);
-	mutex_unlock(&vin->lock);
 	if (ret)
 		return ret;
 
@@ -664,7 +660,6 @@ static int rvin_group_notify_complete(struct v4l2_async_notifier *notifier)
 	}
 
 	/* Create all media device links between VINs and CSI-2's. */
-	mutex_lock(&vin->group->lock);
 	for (route = vin->info->routes; route->mask; route++) {
 		struct media_pad *source_pad, *sink_pad;
 		struct media_entity *source, *sink;
@@ -700,7 +695,6 @@ static int rvin_group_notify_complete(struct v4l2_async_notifier *notifier)
 			break;
 		}
 	}
-	mutex_unlock(&vin->group->lock);
 
 	return ret;
 }
@@ -716,8 +710,6 @@ static void rvin_group_notify_unbind(struct v4l2_async_notifier *notifier,
 		if (vin->group->vin[i])
 			rvin_v4l2_unregister(vin->group->vin[i]);
 
-	mutex_lock(&vin->group->lock);
-
 	for (i = 0; i < RVIN_CSI_MAX; i++) {
 		if (vin->group->csi[i].fwnode != asd->match.fwnode)
 			continue;
@@ -725,8 +717,6 @@ static void rvin_group_notify_unbind(struct v4l2_async_notifier *notifier,
 		vin_dbg(vin, "Unbind CSI-2 %s from slot %u\n", subdev->name, i);
 		break;
 	}
-
-	mutex_unlock(&vin->group->lock);
 }
 
 static int rvin_group_notify_bound(struct v4l2_async_notifier *notifier,
@@ -736,8 +726,6 @@ static int rvin_group_notify_bound(struct v4l2_async_notifier *notifier,
 	struct rvin_dev *vin = v4l2_dev_to_vin(notifier->v4l2_dev);
 	unsigned int i;
 
-	mutex_lock(&vin->group->lock);
-
 	for (i = 0; i < RVIN_CSI_MAX; i++) {
 		if (vin->group->csi[i].fwnode != asd->match.fwnode)
 			continue;
@@ -746,8 +734,6 @@ static int rvin_group_notify_bound(struct v4l2_async_notifier *notifier,
 		break;
 	}
 
-	mutex_unlock(&vin->group->lock);
-
 	return 0;
 }