thermal: core: Update thermal zones after cooling device binding

If a new cooling device is registered and it is bound to at least one
trip point in a given thermal zone, that thermal zone needs to be
updated via __thermal_zone_device_update().

Instead of doing this with the help of the need_update atomic field in
struct thermal_zone_device, which is not particularly straightforward,
make __thermal_zone_cdev_bind() return a bool value indicating whether
or not the given thermal zone needs to be updated because a new cooling
device has been bound to it and update thermal_zone_cdev_bind() to
call __thermal_zone_device_update() when this value is "true".

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <[email protected]>
Link: https://patch.msgid.link/[email protected]
Reviewed-by: Lukasz Luba <[email protected]>

Author: rafaeljw

drivers/thermal/thermal_core.c

@@ -935,13 +935,14 @@ void print_bind_err_msg(struct thermal_zone_device *tz,
 		cdev->type, thermal_zone_trip_id(tz, trip), ret);
 }
 
-static void __thermal_zone_cdev_bind(struct thermal_zone_device *tz,
+static bool __thermal_zone_cdev_bind(struct thermal_zone_device *tz,
 				     struct thermal_cooling_device *cdev)
 {
 	struct thermal_trip_desc *td;
+	bool update_tz = false;
 
 	if (!tz->ops.should_bind)
-		return;
+		return false;
 
 	for_each_trip_desc(tz, td) {
 		struct thermal_trip *trip = &td->trip;
@@ -956,17 +957,24 @@ static void __thermal_zone_cdev_bind(struct thermal_zone_device *tz,
 			continue;
 
 		ret = thermal_bind_cdev_to_trip(tz, trip, cdev, &c);
-		if (ret)
+		if (ret) {
 			print_bind_err_msg(tz, trip, cdev, ret);
+			continue;
+		}
+
+		update_tz = true;
 	}
+
+	return update_tz;
 }
 
 static void thermal_zone_cdev_bind(struct thermal_zone_device *tz,
 				   struct thermal_cooling_device *cdev)
 {
 	mutex_lock(&tz->lock);
 
-	__thermal_zone_cdev_bind(tz, cdev);
+	if (__thermal_zone_cdev_bind(tz, cdev))
+		__thermal_zone_device_update(tz, THERMAL_EVENT_UNSPECIFIED);
 
 	mutex_unlock(&tz->lock);
 }
@@ -993,7 +1001,7 @@ __thermal_cooling_device_register(struct device_node *np,
 				  const struct thermal_cooling_device_ops *ops)
 {
 	struct thermal_cooling_device *cdev;
-	struct thermal_zone_device *pos = NULL;
+	struct thermal_zone_device *pos;
 	unsigned long current_state;
 	int id, ret;
 
@@ -1069,11 +1077,6 @@ __thermal_cooling_device_register(struct device_node *np,
 	list_for_each_entry(pos, &thermal_tz_list, node)
 		thermal_zone_cdev_bind(pos, cdev);
 
-	list_for_each_entry(pos, &thermal_tz_list, node)
-		if (atomic_cmpxchg(&pos->need_update, 1, 0))
-			thermal_zone_device_update(pos,
-						   THERMAL_EVENT_UNSPECIFIED);
-
 	mutex_unlock(&thermal_list_lock);
 
 	return cdev;