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Wysocki" To: Linux PM Cc: LKML , Daniel Lezcano , Lukasz Luba , Srinivas Pandruvada , Zhang Rui Subject: [PATCH v1 2/2] thermal: gov_bang_bang: Fix possible cooling device state ping-pong Date: Mon, 15 Jan 2024 18:57:06 +0100 Message-ID: <2339862.ElGaqSPkdT@kreacher> In-Reply-To: <12389773.O9o76ZdvQC@kreacher> References: <12389773.O9o76ZdvQC@kreacher> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CLIENT-IP: 195.136.19.94 X-CLIENT-HOSTNAME: 195.136.19.94 X-VADE-SPAMSTATE: clean X-VADE-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedvkedrvdejuddguddtjecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfjqffogffrnfdpggftiffpkfenuceurghilhhouhhtmecuudehtdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvvefufffkjghfggfgtgesthfuredttddtjeenucfhrhhomhepfdftrghfrggvlhculfdrucghhihsohgtkhhifdcuoehrjhifsehrjhifhihsohgtkhhirdhnvghtqeenucggtffrrghtthgvrhhnpedvffeuiedtgfdvtddugeeujedtffetteegfeekffdvfedttddtuefhgeefvdejhfenucfkphepudelhedrudefiedrudelrdelgeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeduleehrddufeeirdduledrleegpdhhvghlohepkhhrvggrtghhvghrrdhlohgtrghlnhgvthdpmhgrihhlfhhrohhmpedftfgrfhgrvghlucflrdcuhgihshhotghkihdfuceorhhjfiesrhhjfiihshhotghkihdrnhgvtheqpdhnsggprhgtphhtthhopeeipdhrtghpthhtoheplhhinhhugidqphhmsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdhorhhgpdhrtghpthhtohepuggrnhhivghlrdhlvgiitggrnhhosehlihhnrghrohdrohhrghdprhgtphhtthhopehluhhkrghsiidrlhhusggrsegrrhhmrdgtohhmpdhrtghpthhtohepshhr ihhnihhvrghsrdhprghnughruhhvrggurgeslhhinhhugidrihhnthgvlhdrtghomhdprhgtphhtthhopehruhhirdiihhgrnhhgsehinhhtvghlrdgtohhm X-DCC--Metrics: v370.home.net.pl 1024; Body=6 Fuz1=6 Fuz2=6 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1788180160987692516 X-GMAIL-MSGID: 1788180160987692516 From: Rafael J. Wysocki 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(-) Index: linux-pm/drivers/thermal/gov_bang_bang.c =================================================================== --- linux-pm.orig/drivers/thermal/gov_bang_bang.c +++ linux-pm/drivers/thermal/gov_bang_bang.c @@ -49,7 +49,7 @@ static int thermal_zone_trip_update(stru 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",