linux-kernel - [PATCH v2 09/12] thermal: core: Update thermal zones after cooling device binding

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Message-ID: <2226302.Icojqenx9y@rjwysocki.net>
Date: Fri, 04 Oct 2024 21:33:28 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Lukasz Luba <lukasz.luba@....com>, Zhang Rui <rui.zhang@...el.com>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject:
 [PATCH v2 09/12] thermal: core: Update thermal zones after cooling device
 binding

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

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 <rafael.j.wysocki@...el.com>
---

This is a new iteration of

https://lore.kernel.org/linux-pm/3603909.iIbC2pHGDl@rjwysocki.net/

v1 -> v2: Rebase.

---
 drivers/thermal/thermal_core.c |   23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -933,13 +933,14 @@ void print_bind_err_msg(struct thermal_z
 		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;
@@ -954,9 +955,15 @@ static void __thermal_zone_cdev_bind(str
 			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,
@@ -964,7 +971,8 @@ static void thermal_zone_cdev_bind(struc
 {
 	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);
 }
@@ -991,7 +999,7 @@ __thermal_cooling_device_register(struct
 				  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;

@@ -1067,11 +1075,6 @@ __thermal_cooling_device_register(struct
 	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;