From 54d94009cb6f51d3ecd56bfc63c83e789c0b18b4 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Mon, 15 Jan 2024 18:57:06 +0100 Subject: [PATCH] thermal: gov_bang_bang: Fix possible cooling device state ping-pong The current behavior of thermal_zone_trip_update() in the bang-bang thermal governor may be problematic for trip points with 0 hysteresis, because when the zone temperature reaches the trip temperature and stays there, it will then cause the cooling device go "on" and "off" alternately, which is not desirable. Address this by requiring the zone temperature to actually fall below trip->temperature - trip->hysteresis for the cooling device to go off. Signed-off-by: Rafael J. Wysocki --- drivers/thermal/gov_bang_bang.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/thermal/gov_bang_bang.c b/drivers/thermal/gov_bang_bang.c index 6ddf0accdc98..c3b2943a2db8 100644 --- a/drivers/thermal/gov_bang_bang.c +++ b/drivers/thermal/gov_bang_bang.c @@ -49,7 +49,7 @@ static int thermal_zone_trip_update(struct thermal_zone_device *tz, if (instance->target == 0 && tz->temperature >= trip->temperature) instance->target = 1; else if (instance->target == 1 && - tz->temperature <= trip->temperature - trip->hysteresis) + tz->temperature < trip->temperature - trip->hysteresis) instance->target = 0; dev_dbg(&instance->cdev->device, "target=%d\n",