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97 lines
3.4 KiB
Diff
97 lines
3.4 KiB
Diff
From bcf41a406eb1c0e2a7f3e5ac0baef5455933afd7 Mon Sep 17 00:00:00 2001
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From: Ram Chandrasekar <rkumbako@codeaurora.org>
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Date: Mon, 7 May 2018 11:54:08 -0600
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Subject: [PATCH 426/454] drivers: thermal: step_wise: add support for
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hysteresis
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From: Ram Chandrasekar <rkumbako@codeaurora.org>
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Step wise governor increases the mitigation level when the temperature
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goes above a threshold and will decrease the mitigation when the
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temperature falls below the threshold. If it were a case, where the
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temperature hovers around a threshold, the mitigation will be applied
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and removed at every iteration. This reaction to the temperature is
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inefficient for performance.
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The use of hysteresis temperature could avoid this ping-pong of
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mitigation by relaxing the mitigation to happen only when the
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temperature goes below this lower hysteresis value.
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Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>
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Signed-off-by: Lina Iyer <ilina@codeaurora.org>
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---
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drivers/thermal/step_wise.c | 33 +++++++++++++++++++++++----------
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1 file changed, 23 insertions(+), 10 deletions(-)
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--- a/drivers/thermal/step_wise.c
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+++ b/drivers/thermal/step_wise.c
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@@ -36,7 +36,7 @@
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* for this trip point
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* d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit
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* for this trip point
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- * If the temperature is lower than a trip point,
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+ * If the temperature is lower than a hysteresis temperature,
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* a. if the trend is THERMAL_TREND_RAISING, do nothing
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* b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
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* state for this trip point, if the cooling state already
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@@ -127,7 +127,7 @@ static void update_passive_instance(stru
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static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
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{
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- int trip_temp;
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+ int trip_temp, hyst_temp;
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enum thermal_trip_type trip_type;
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enum thermal_trend trend;
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struct thermal_instance *instance;
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@@ -135,22 +135,23 @@ static void thermal_zone_trip_update(str
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int old_target;
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if (trip == THERMAL_TRIPS_NONE) {
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- trip_temp = tz->forced_passive;
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+ hyst_temp = trip_temp = tz->forced_passive;
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trip_type = THERMAL_TRIPS_NONE;
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} else {
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tz->ops->get_trip_temp(tz, trip, &trip_temp);
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+ hyst_temp = trip_temp;
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+ if (tz->ops->get_trip_hyst) {
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+ tz->ops->get_trip_hyst(tz, trip, &hyst_temp);
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+ hyst_temp = trip_temp - hyst_temp;
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+ }
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tz->ops->get_trip_type(tz, trip, &trip_type);
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}
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trend = get_tz_trend(tz, trip);
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- if (tz->temperature >= trip_temp) {
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- throttle = true;
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- trace_thermal_zone_trip(tz, trip, trip_type);
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- }
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-
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- dev_dbg(&tz->device, "Trip%d[type=%d,temp=%d]:trend=%d,throttle=%d\n",
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- trip, trip_type, trip_temp, trend, throttle);
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+ dev_dbg(&tz->device,
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+ "Trip%d[type=%d,temp=%d,hyst=%d]:trend=%d,throttle=%d\n",
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+ trip, trip_type, trip_temp, hyst_temp, trend, throttle);
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mutex_lock(&tz->lock);
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@@ -159,6 +160,18 @@ static void thermal_zone_trip_update(str
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continue;
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old_target = instance->target;
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+ throttle = false;
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+ /*
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+ * Lower the mitigation only if the temperature
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+ * goes below the hysteresis temperature.
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+ */
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+ if (tz->temperature >= trip_temp ||
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+ (tz->temperature >= hyst_temp &&
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+ old_target != THERMAL_NO_TARGET)) {
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+ throttle = true;
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+ trace_thermal_zone_trip(tz, trip, trip_type);
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+ }
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+
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instance->target = get_target_state(instance, trend, throttle);
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dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n",
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old_target, (int)instance->target);
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