thermal/of: Fix cdev lookup in thermal_of_should_bind()

JIRA: https://issues.redhat.com/browse/RHEL-79821

commit 423de5b5bc5b267586b449abd1c4fde562aa0cf9
Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date:   Fri Feb 21 17:57:11 2025 +0100

    thermal/of: Fix cdev lookup in thermal_of_should_bind()

    Since thermal_of_should_bind() terminates the loop after processing
    the first child found in cooling-maps, it will never match more than
    one cdev to a given trip point which is incorrect, as there may be
    cooling-maps associating one trip point with multiple cooling devices.

    Address this by letting the loop continue until either all
    children have been processed or a matching one has been found.

    To avoid adding conditionals or goto statements, put the loop in
    question into a separate function and make that function return
    right away after finding a matching cooling-maps entry.

    Fixes: 94c6110b0b13 ("thermal/of: Use the .should_bind() thermal zone callback")
    Link: https://lore.kernel.org/linux-pm/20250219-fix-thermal-of-v1-1-de36e7a590c4@chromium.org/


Reported-by: Yu-Che Cheng <giver@chromium.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Yu-Che Cheng <giver@chromium.org>
Tested-by: Yu-Che Cheng <giver@chromium.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
    Link: https://patch.msgid.link/2788228.mvXUDI8C0e@rjwysocki.net



Signed-off-by: David Arcari <darcari@redhat.com>

drivers/thermal/thermal_of.c

@@ -296,6 +296,34 @@ static bool thermal_of_get_cooling_spec(struct device_node *map_np, int index,
 	return true;
 }
 
+static bool thermal_of_cm_lookup(struct device_node *cm_np,
+				 const struct thermal_trip *trip,
+				 struct thermal_cooling_device *cdev,
+				 struct cooling_spec *c)
+{
+	for_each_child_of_node_scoped(cm_np, child) {
+		struct device_node *tr_np;
+		int count, i;
+
+		tr_np = of_parse_phandle(child, "trip", 0);
+		if (tr_np != trip->priv)
+			continue;
+
+		/* The trip has been found, look up the cdev. */
+		count = of_count_phandle_with_args(child, "cooling-device",
+						   "#cooling-cells");
+		if (count <= 0)
+			pr_err("Add a cooling_device property with at least one device\n");
+
+		for (i = 0; i < count; i++) {
+			if (thermal_of_get_cooling_spec(child, i, cdev, c))
+				return true;
+		}
+	}
+
+	return false;
+}
+
 static bool thermal_of_should_bind(struct thermal_zone_device *tz,
 				   const struct thermal_trip *trip,
 				   struct thermal_cooling_device *cdev,
@@ -315,27 +343,7 @@ static bool thermal_of_should_bind(struct thermal_zone_device *tz,
 		goto out;
 
 	/* Look up the trip and the cdev in the cooling maps. */
-	for_each_child_of_node_scoped(cm_np, child) {
-		struct device_node *tr_np;
-		int count, i;
-
-		tr_np = of_parse_phandle(child, "trip", 0);
-		if (tr_np != trip->priv)
-			continue;
-
-		/* The trip has been found, look up the cdev. */
-		count = of_count_phandle_with_args(child, "cooling-device", "#cooling-cells");
-		if (count <= 0)
-			pr_err("Add a cooling_device property with at least one device\n");
-
-		for (i = 0; i < count; i++) {
-			result = thermal_of_get_cooling_spec(child, i, cdev, c);
-			if (result)
-				break;
-		}
-
-		break;
-	}
+	result = thermal_of_cm_lookup(cm_np, trip, cdev, c);
 
 	of_node_put(cm_np);
 out: