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Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch')
-rw-r--r--target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch96
1 files changed, 96 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch b/target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch
new file mode 100644
index 0000000000..af447c1704
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.19/950-0157-drivers-thermal-step_wise-add-support-for-hysteresis.patch
@@ -0,0 +1,96 @@
+From 05a13bbd7fbb76b4f690042173749a55d85de831 Mon Sep 17 00:00:00 2001
+From: Ram Chandrasekar <rkumbako@codeaurora.org>
+Date: Mon, 7 May 2018 11:54:08 -0600
+Subject: [PATCH] drivers: thermal: step_wise: add support for
+ hysteresis
+
+From: Ram Chandrasekar <rkumbako@codeaurora.org>
+
+Step wise governor increases the mitigation level when the temperature
+goes above a threshold and will decrease the mitigation when the
+temperature falls below the threshold. If it were a case, where the
+temperature hovers around a threshold, the mitigation will be applied
+and removed at every iteration. This reaction to the temperature is
+inefficient for performance.
+
+The use of hysteresis temperature could avoid this ping-pong of
+mitigation by relaxing the mitigation to happen only when the
+temperature goes below this lower hysteresis value.
+
+Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>
+Signed-off-by: Lina Iyer <ilina@codeaurora.org>
+---
+ drivers/thermal/step_wise.c | 33 +++++++++++++++++++++++----------
+ 1 file changed, 23 insertions(+), 10 deletions(-)
+
+--- a/drivers/thermal/step_wise.c
++++ b/drivers/thermal/step_wise.c
+@@ -36,7 +36,7 @@
+ * for this trip point
+ * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
+ * for this trip point
+- * If the temperature is lower than a trip point,
++ * If the temperature is lower than a hysteresis temperature,
+ * a. if the trend is THERMAL_TREND_RAISING, do nothing
+ * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
+ * state for this trip point, if the cooling state already
+@@ -127,7 +127,7 @@ static void update_passive_instance(stru
+
+ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
+ {
+- int trip_temp;
++ int trip_temp, hyst_temp;
+ enum thermal_trip_type trip_type;
+ enum thermal_trend trend;
+ struct thermal_instance *instance;
+@@ -135,22 +135,23 @@ static void thermal_zone_trip_update(str
+ int old_target;
+
+ if (trip == THERMAL_TRIPS_NONE) {
+- trip_temp = tz->forced_passive;
++ hyst_temp = trip_temp = tz->forced_passive;
+ trip_type = THERMAL_TRIPS_NONE;
+ } else {
+ tz->ops->get_trip_temp(tz, trip, &trip_temp);
++ hyst_temp = trip_temp;
++ if (tz->ops->get_trip_hyst) {
++ tz->ops->get_trip_hyst(tz, trip, &hyst_temp);
++ hyst_temp = trip_temp - hyst_temp;
++ }
+ tz->ops->get_trip_type(tz, trip, &trip_type);
+ }
+
+ trend = get_tz_trend(tz, trip);
+
+- if (tz->temperature >= trip_temp) {
+- throttle = true;
+- trace_thermal_zone_trip(tz, trip, trip_type);
+- }
+-
+- dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
+- trip, trip_type, trip_temp, trend, throttle);
++ dev_dbg(&tz->device,
++ "Trip%d[type=%d,temp=%d,hyst=%d]:trend=%d,throttle=%d\n",
++ trip, trip_type, trip_temp, hyst_temp, trend, throttle);
+
+ mutex_lock(&tz->lock);
+
+@@ -159,6 +160,18 @@ static void thermal_zone_trip_update(str
+ continue;
+
+ old_target = instance->target;
++ throttle = false;
++ /*
++ * Lower the mitigation only if the temperature
++ * goes below the hysteresis temperature.
++ */
++ if (tz->temperature >= trip_temp ||
++ (tz->temperature >= hyst_temp &&
++ old_target != THERMAL_NO_TARGET)) {
++ throttle = true;
++ trace_thermal_zone_trip(tz, trip, trip_type);
++ }
++
+ instance->target = get_target_state(instance, trend, throttle);
+ dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
+ old_target, (int)instance->target);