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

Rafael J. Wysocki
2024-05-23T16:05:18Z

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@intel.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);