linux-kernel - [PATCH 3.13.y-ckt 063/122] thermal: step

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Message-Id: <1434580149-3095-64-git-send-email-kamal@canonical.com>
Date:	Wed, 17 Jun 2015 15:28:10 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Jean Delvare <jdelvare@...e.de>,
	Luis Henriques <luis.henriques@...onical.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13.y-ckt 063/122] thermal: step_wise: Revert optimization

3.13.11-ckt22 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jean Delvare <jdelvare@...e.de>

Commit 178c2490b99f898efc06d1ad75cadc84f13021a6 ("thermal: step_wise:
cdev only needs update on a new target state") broke driver acerhdf.
That driver abused the step_wise thermal governor until the bang_bang
governor was available, and the optimization broke this usage model.

Kernels v3.12 to v3.18 are affected. In v3.19 the acerhdf driver was
switched to the bang_bang governor and that solved the problem.

For kernels v3.12 to v3.17, the bang_bang governor isn't available
yet so the easiest fix is to revert the optimization.

Signed-off-by: Jean Delvare <jdelvare@...e.de>
Reported-by: Dieter Jurzitza (https://bugzilla.opensuse.org/show_bug.cgi?id=925961)
Tested-by: Peter Feuerer <peter@...e.net>
Tested-by: Dieter Jurzitza
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/thermal/step_wise.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c
index d89e781..769bfa3 100644
--- a/drivers/thermal/step_wise.c
+++ b/drivers/thermal/step_wise.c
@@ -140,9 +140,6 @@ static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
 		old_target = instance->target;
 		instance->target = get_target_state(instance, trend, throttle);
 
-		if (old_target == instance->target)
-			continue;
-
 		/* Activate a passive thermal instance */
 		if (old_target == THERMAL_NO_TARGET &&
 			instance->target != THERMAL_NO_TARGET)
-- 
1.9.1

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