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![Rafael J. Wysocki](/assets/img/avatar_default.png)
Passive polling is enabled by setting the 'passive' field in struct thermal_zone_device to a positive value so long as the 'passive_delay_jiffies' field is greater than zero. It causes the thermal core to actively check the thermal zone temperature periodically which in theory should be done after crossing a passive trip point on the way up in order to allow governors to react more rapidly to temperature changes and adjust mitigation more precisely. However, the 'passive' field in struct thermal_zone_device is currently managed by governors which is quite problematic. First of all, only two governors, Step-Wise and Power Allocator, update that field at all, so the other governors do not benefit from passive polling, although in principle they should. Moreover, if the zone governor is changed from, say, Step-Wise to Fair-Share after 'passive' has been incremented by the former, it is not going to be reset back to zero by the latter even if the zone temperature falls down below all passive trip points. For this reason, make handle_thermal_trip() increment 'passive' to enable passive polling for the given thermal zone whenever a passive trip point is crossed on the way up and decrement it whenever a passive trip point is crossed on the way down. Also remove the 'passive' field updates from governors and additionally clear it in thermal_zone_device_init() to prevent passive polling from being enabled after a system resume just beacuse it was enabled before suspending the system. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Lukasz Luba <lukasz.luba@arm.com> Tested-by: Lukasz Luba <lukasz.luba@arm.com>
138 lines
4 KiB
C
138 lines
4 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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/*
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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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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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return clamp(cur_state + 1, instance->lower, instance->upper);
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return THERMAL_NO_TARGET;
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}
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if (throttle) {
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if (trend == THERMAL_TREND_RAISING)
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return clamp(cur_state + 1, instance->lower, instance->upper);
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} else if (trend == THERMAL_TREND_DROPPING) {
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if (cur_state <= instance->lower)
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return THERMAL_NO_TARGET;
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return clamp(cur_state - 1, instance->lower, instance->upper);
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}
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return instance->target;
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}
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static void thermal_zone_trip_update(struct thermal_zone_device *tz,
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const struct thermal_trip *trip,
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int trip_threshold)
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{
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enum thermal_trend trend = get_tz_trend(tz, trip);
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int trip_id = thermal_zone_trip_id(tz, trip);
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struct thermal_instance *instance;
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bool throttle = false;
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if (tz->temperature >= trip_threshold) {
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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_threshold, trend, throttle);
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
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int old_target;
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if (instance->trip != trip)
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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=%ld\n",
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old_target, instance->target);
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if (instance->initialized && old_target == instance->target)
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continue;
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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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static void step_wise_manage(struct thermal_zone_device *tz)
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{
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const struct thermal_trip_desc *td;
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struct thermal_instance *instance;
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lockdep_assert_held(&tz->lock);
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/*
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* Throttling Logic: Use the trend of the thermal zone to throttle.
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* If the thermal zone is 'heating up', throttle all of the cooling
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* devices associated with each trip point by one step. If the zone
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* is 'cooling down', it brings back the performance of the devices
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* by one step.
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*/
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for_each_trip_desc(tz, td) {
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const struct thermal_trip *trip = &td->trip;
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if (trip->temperature == THERMAL_TEMP_INVALID ||
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trip->type == THERMAL_TRIP_CRITICAL ||
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trip->type == THERMAL_TRIP_HOT)
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continue;
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thermal_zone_trip_update(tz, trip, td->threshold);
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}
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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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}
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static struct thermal_governor thermal_gov_step_wise = {
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.name = "step_wise",
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.manage = step_wise_manage,
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};
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THERMAL_GOVERNOR_DECLARE(thermal_gov_step_wise);
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