[PATCH v3 3/6] thermal: core: Rewrite comments in handle_thermal_trip()

From: Rafael J. Wysocki
Date: Tue Apr 02 2024 - 15:06:02 EST


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

Make the comments regarding trip crossing and threshold updates in
handle_thermal_trip() slightly more clear.

No functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---

v2 -> v3: New patch

---
drivers/thermal/thermal_core.c | 26 +++++++++++++-------------
1 file changed, 13 insertions(+), 13 deletions(-)

Index: linux-pm/drivers/thermal/thermal_core.c
===================================================================
--- linux-pm.orig/drivers/thermal/thermal_core.c
+++ linux-pm/drivers/thermal/thermal_core.c
@@ -368,6 +368,13 @@ static void handle_thermal_trip(struct t
if (trip->temperature == THERMAL_TEMP_INVALID)
return;

+ /*
+ * If the trip temperature or hysteresis has been updated recently,
+ * the threshold needs to be computed again using the new values.
+ * However, its initial value still reflects the old ones and that
+ * is what needs to be compared with the previous zone temperature
+ * to decide which action to take.
+ */
if (tz->last_temperature == THERMAL_TEMP_INVALID) {
/* Initialization. */
td->threshold = trip->temperature;
@@ -375,11 +382,9 @@ static void handle_thermal_trip(struct t
td->threshold -= trip->hysteresis;
} else if (tz->last_temperature < td->threshold) {
/*
- * The trip threshold is equal to the trip temperature, unless
- * the latter has changed in the meantime. In either case,
- * the trip is crossed if the current zone temperature is at
- * least equal to its temperature, but otherwise ensure that
- * the threshold and the trip temperature will be equal.
+ * There is no mitigation under way, so it needs to be started
+ * if the zone temperature exceeds the trip one. The new
+ * threshold is then set to the low temperature of the trip.
*/
if (tz->temperature >= trip->temperature) {
thermal_notify_tz_trip_up(tz, trip);
@@ -390,14 +395,9 @@ static void handle_thermal_trip(struct t
}
} else {
/*
- * The previous zone temperature was above or equal to the trip
- * threshold, which would be equal to the "low temperature" of
- * the trip (its temperature minus its hysteresis), unless the
- * trip temperature or hysteresis had changed. In either case,
- * the trip is crossed if the current zone temperature is below
- * the low temperature of the trip, but otherwise ensure that
- * the trip threshold will be equal to the low temperature of
- * the trip.
+ * Mitigation is under way, so it needs to stop if the zone
+ * temperature falls below the low temperature of the trip.
+ * In that case, the trip temperature becomes the new threshold.
*/
if (tz->temperature < trip->temperature - trip->hysteresis) {
thermal_notify_tz_trip_down(tz, trip);