linux-kernel - [PATCH 1/2] thermal: power_allocator: maintain the device statistics from going stale

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Message-Id: <20210331163352.32416-2-lukasz.luba@arm.com>
Date:   Wed, 31 Mar 2021 17:33:51 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     linux-kernel@...r.kernel.org, daniel.lezcano@...aro.org
Cc:     linux-pm@...r.kernel.org, amitk@...nel.org, rui.zhang@...el.com,
        lukasz.luba@....com
Subject: [PATCH 1/2] thermal: power_allocator: maintain the device statistics from going stale

When the temperature is below the first activation trip point the cooling
devices are not checked, so they cannot maintain fresh statistics. It
leads into the situation, when temperature crosses first trip point, the
statistics are stale and show state for very long period. This has impact
on IPA algorithm calculation and wrong decisions. Thus, check the cooling
devices even when the temperature is low, to refresh these statistics.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 drivers/thermal/gov_power_allocator.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
index 2802a0e13c88..0cbd10cab193 100644
--- a/drivers/thermal/gov_power_allocator.c
+++ b/drivers/thermal/gov_power_allocator.c
@@ -575,15 +575,27 @@ static void allow_maximum_power(struct thermal_zone_device *tz)
 {
 	struct thermal_instance *instance;
 	struct power_allocator_params *params = tz->governor_data;
+	u32 req_power;
 
 	mutex_lock(&tz->lock);
 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		struct thermal_cooling_device *cdev = instance->cdev;
+
 		if ((instance->trip != params->trip_max_desired_temperature) ||
 		    (!cdev_is_power_actor(instance->cdev)))
 			continue;
 
 		instance->target = 0;
 		mutex_lock(&instance->cdev->lock);
+		/*
+		 * Call for updating the cooling devices local stats and avoid
+		 * periods of dozen of seconds when those have not been
+		 * maintained. The long period would come into the first check
+		 * when lower threshold is crossed. Thus, limit it to single
+		 * one longer polling period.
+		 */
+		cdev->ops->get_requested_power(cdev, &req_power);
+
 		instance->cdev->updated = false;
 		mutex_unlock(&instance->cdev->lock);
 		thermal_cdev_update(instance->cdev);
-- 
2.17.1