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e4006bfec1
For the algorithm of choosing the next target state in step_wise governor, the code does the right thing but is implemented in a way different from what the comment describes. And this hurts the code readability. As the logic in the comment is simpler, adjust the code logic to align with the comment. No functional change. Signed-off-by: Zhang Rui <rui.zhang@intel.com> [ rjw: Subject edit ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
160 lines
4.7 KiB
C
160 lines
4.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* step_wise.c - A step-by-step Thermal throttling governor
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*
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* Copyright (C) 2012 Intel Corp
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* Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*/
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#include <linux/thermal.h>
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#include <linux/minmax.h>
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#include "thermal_trace.h"
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#include "thermal_core.h"
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/*
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* If the temperature is higher than a trip point,
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* a. if the trend is THERMAL_TREND_RAISING, use higher cooling
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* state for this trip point
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* b. if the trend is THERMAL_TREND_DROPPING, do nothing
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* If the temperature is lower than a trip point,
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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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* equals lower limit, deactivate the thermal instance
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*/
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static unsigned long get_target_state(struct thermal_instance *instance,
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enum thermal_trend trend, bool throttle)
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{
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struct thermal_cooling_device *cdev = instance->cdev;
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unsigned long cur_state;
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unsigned long next_target;
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/*
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* We keep this instance the way it is by default.
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* Otherwise, we use the current state of the
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* cdev in use to determine the next_target.
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*/
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cdev->ops->get_cur_state(cdev, &cur_state);
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next_target = instance->target;
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dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state);
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if (!instance->initialized) {
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if (throttle) {
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next_target = clamp((cur_state + 1), instance->lower, instance->upper);
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} else {
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next_target = THERMAL_NO_TARGET;
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}
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return next_target;
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}
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if (throttle) {
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if (trend == THERMAL_TREND_RAISING)
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next_target = clamp((cur_state + 1), instance->lower, instance->upper);
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} else {
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if (trend == THERMAL_TREND_DROPPING) {
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if (cur_state <= instance->lower)
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next_target = THERMAL_NO_TARGET;
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else
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next_target = clamp((cur_state - 1), instance->lower, instance->upper);
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}
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}
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return next_target;
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}
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static void update_passive_instance(struct thermal_zone_device *tz,
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enum thermal_trip_type type, int value)
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{
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/*
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* If value is +1, activate a passive instance.
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* If value is -1, deactivate a passive instance.
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*/
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if (type == THERMAL_TRIP_PASSIVE)
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tz->passive += value;
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}
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static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip_id)
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{
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enum thermal_trend trend;
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struct thermal_instance *instance;
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struct thermal_trip trip;
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bool throttle = false;
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int old_target;
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__thermal_zone_get_trip(tz, trip_id, &trip);
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trend = get_tz_trend(tz, trip_id);
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if (tz->temperature >= trip.temperature) {
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throttle = true;
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trace_thermal_zone_trip(tz, trip_id, trip.type);
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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_id, trip.type, trip.temperature, trend, throttle);
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
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if (instance->trip != trip_id)
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continue;
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old_target = instance->target;
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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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if (instance->initialized && old_target == instance->target)
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continue;
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/* Activate a passive thermal instance */
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if (old_target == THERMAL_NO_TARGET &&
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instance->target != THERMAL_NO_TARGET)
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update_passive_instance(tz, trip.type, 1);
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/* Deactivate a passive thermal instance */
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else if (old_target != THERMAL_NO_TARGET &&
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instance->target == THERMAL_NO_TARGET)
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update_passive_instance(tz, trip.type, -1);
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instance->initialized = true;
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mutex_lock(&instance->cdev->lock);
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instance->cdev->updated = false; /* cdev needs update */
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mutex_unlock(&instance->cdev->lock);
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}
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}
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/**
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* step_wise_throttle - throttles devices associated with the given zone
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* @tz: thermal_zone_device
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* @trip: trip point index
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*
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* Throttling Logic: This uses the trend of the thermal zone to throttle.
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* If the thermal zone is 'heating up' this throttles all the cooling
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* devices associated with the zone and its particular trip point, by one
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* step. If the zone is 'cooling down' it brings back the performance of
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* the devices by one step.
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*/
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static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
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{
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struct thermal_instance *instance;
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lockdep_assert_held(&tz->lock);
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thermal_zone_trip_update(tz, trip);
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list_for_each_entry(instance, &tz->thermal_instances, tz_node)
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thermal_cdev_update(instance->cdev);
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return 0;
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}
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static struct thermal_governor thermal_gov_step_wise = {
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.name = "step_wise",
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.throttle = step_wise_throttle,
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};
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THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);
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