thermal/core: Fix thermal trip cross pointthermal/debugfs-v2

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

2 files changed, 24 insertions, 10 deletions

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d4207805b6f670..264db84107296a 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -357,19 +357,30 @@ static void handle_critical_trips(struct thermal_zone_device *tz,
 static void handle_thermal_trip_crossed(struct thermal_zone_device *tz, int trip,
 					int trip_temp, int trip_hyst, enum thermal_trip_type trip_type)
 {
+	int trip_low_temp = trip_temp - trip_hyst;
+
 	if (tz->last_temperature == THERMAL_TEMP_INVALID)
 		return;
 
-	if (tz->last_temperature < trip_temp &&
-	    tz->temperature >= trip_temp) {
-		thermal_notify_tz_trip_up(tz->id, trip,
-					  tz->temperature);
-	}
-
-	if (tz->last_temperature >= trip_temp &&
-	    tz->temperature < (trip_temp - trip_hyst)) {
-		thermal_notify_tz_trip_down(tz->id, trip,
-					    tz->temperature);
+	/*
+	 * Due to the hysteresis, a third information is needed to
+	 * detect when the temperature is wavering between the
+	 * trip_low_temp and the trip_temp. A trip point is crossed
+	 * the way up only if the temperature is above it while the
+	 * previous temperature was below *and* we crossed the
+	 * trip_temp_low before. The previous trip point give us the
+	 * previous trip point transition. The similar problem exists
+	 * when crossing the way down.
+	 */
+	if (tz->last_temperature < trip_temp && tz->temperature >= trip_temp &&
+	    trip != tz->prev_trip) {
+		thermal_notify_tz_trip_up(tz->id, trip, tz->temperature);
+		tz->prev_trip = trip;
+		
+	} else if (tz->last_temperature >= trip_low_temp && tz->temperature < trip_low_temp &&
+	    trip == tz->prev_trip) {
+		thermal_notify_tz_trip_down(tz->id, trip, tz->temperature);
+		tz->prev_trip = trip - 1;
 	}
 }
 
@@ -430,6 +441,7 @@ static void thermal_zone_device_init(struct thermal_zone_device *tz)
 {
 	struct thermal_instance *pos;
 	tz->temperature = THERMAL_TEMP_INVALID;
+	tz->prev_trip = -1;
 	tz->prev_low_trip = -INT_MAX;
 	tz->prev_high_trip = INT_MAX;
 	list_for_each_entry(pos, &tz->thermal_instances, tz_node)
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index c8528bb6c01cb8..81156c16f8bac4 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -127,6 +127,7 @@ struct thermal_cooling_device {
  * @last_temperature:	previous temperature read
  * @emul_temperature:	emulated temperature when using CONFIG_THERMAL_EMULATION
  * @passive:		1 if you've crossed a passive trip point, 0 otherwise.
+ * @prev_trip:		previous trip point the thermal zone was, -1 if below all of them
  * @prev_low_trip:	the low current temperature if you've crossed a passive
 			trip point.
  * @prev_high_trip:	the above current temperature if you've crossed a
@@ -162,6 +163,7 @@ struct thermal_zone_device {
 	int last_temperature;
 	int emul_temperature;
 	int passive;
+	int prev_trip;
 	int prev_low_trip;
 	int prev_high_trip;
 	atomic_t need_update;