linux-kernel - [PATCH v1 4/4] thermal: trip: Trigger trip down notifications when trips involved in mitigation become invalid

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Message-ID: <8373757.T7Z3S40VBb@kreacher>
Date: Thu, 23 May 2024 18:05:03 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 "Rafael J. Wysocki" <rafael@...nel.org>, Lukasz Luba <lukasz.luba@....com>,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
 Zhang Rui <rui.zhang@...el.com>
Subject:
 [PATCH v1 4/4] thermal: trip: Trigger trip down notifications when trips
 involved in mitigation become invalid

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

When a trip point becomes invalid after being crossed on the way up,
it is involved in a mitigation episode that needs to be adjusted to
compensate for the trip going away.

For this reason, introduce thermal_zone_trip_down() as a wrapper
around thermal_trip_crossed() and make thermal_zone_set_trip_temp()
call it if the new temperature of the trip at hand is equal to
THERMAL_TEMP_INVALID and it has been crossed on the way up to trigger
all of the necessary adjustments in user space, the thermal debug
code and the zone governor.

Fixes: 8c69a777e480 ("thermal: core: Fix the handling of invalid trip points")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---

Initially, I had thought that this would be a cleanup rather than a fix, but
then I realized that there was the Bang-bang governor that needed to undo
mitigation when the trip that triggered it became invalid before getting
crossed on the way down.

---
 drivers/thermal/thermal_core.c |    6 ++++++
 drivers/thermal/thermal_core.h |    2 ++
 drivers/thermal/thermal_trip.c |   20 ++++++++++++--------
 3 files changed, 20 insertions(+), 8 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -602,6 +602,12 @@ void thermal_zone_device_update(struct t
 }
 EXPORT_SYMBOL_GPL(thermal_zone_device_update);

+void thermal_zone_trip_down(struct thermal_zone_device *tz,
+			    const struct thermal_trip *trip)
+{
+	thermal_trip_crossed(tz, trip, thermal_get_tz_governor(tz), false);
+}
+
 int for_each_thermal_governor(int (*cb)(struct thermal_governor *, void *),
 			      void *data)
 {
Index: linux-pm/drivers/thermal/thermal_core.h
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.h
+++ linux-pm/drivers/thermal/thermal_core.h
@@ -246,6 +246,8 @@ int thermal_zone_trip_id(const struct th
 void thermal_zone_trip_updated(struct thermal_zone_device *tz,
 			       const struct thermal_trip *trip);
 int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp);
+void thermal_zone_trip_down(struct thermal_zone_device *tz,
+			    const struct thermal_trip *trip);

 /* sysfs I/F */
 int thermal_zone_create_device_groups(struct thermal_zone_device *tz);
Index: linux-pm/drivers/thermal/thermal_trip.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_trip.c
+++ linux-pm/drivers/thermal/thermal_trip.c
@@ -152,17 +152,23 @@ void thermal_zone_set_trip_temp(struct t
 	if (trip->temperature == temp)
 		return;

+	trip->temperature = temp;
+	thermal_notify_tz_trip_change(tz, trip);
+
 	if (temp == THERMAL_TEMP_INVALID) {
 		struct thermal_trip_desc *td = trip_to_trip_desc(trip);

-		if (trip->type == THERMAL_TRIP_PASSIVE &&
-		    tz->temperature >= td->threshold) {
+		if (tz->temperature >= td->threshold) {
 			/*
-			 * The trip has been crossed, so the thermal zone's
-			 * passive count needs to be adjusted.
+			 * The trip has been crossed on the way up, so some
+			 * adjustments are needed to compensate for the lack
+			 * of it going forward.
 			 */
-			tz->passive--;
-			WARN_ON_ONCE(tz->passive < 0);
+			if (trip->type == THERMAL_TRIP_PASSIVE) {
+				tz->passive--;
+				WARN_ON_ONCE(tz->passive < 0);
+			}
+			thermal_zone_trip_down(tz, trip);
 		}
 		/*
 		 * Invalidate the threshold to avoid triggering a spurious
@@ -170,7 +176,5 @@ void thermal_zone_set_trip_temp(struct t
 		 */
 		td->threshold = INT_MAX;
 	}
-	trip->temperature = temp;
-	thermal_notify_tz_trip_change(tz, trip);
 }
 EXPORT_SYMBOL_GPL(thermal_zone_set_trip_temp);