From: Rafael J. Wysocki Date: Mon, 15 Jan 2024 17:57:06 +0000 (+0100) Subject: thermal: gov_bang_bang: Fix possible cooling device state ping-pong X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=54d94009cb6f51d3ecd56bfc63c83e789c0b18b4;p=linux.git 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 --- diff --git a/drivers/thermal/gov_bang_bang.c b/drivers/thermal/gov_bang_bang.c index 6ddf0accdc98f..c3b2943a2db8b 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",