Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752880AbbGULlQ (ORCPT ); Tue, 21 Jul 2015 07:41:16 -0400 Received: from smtp2-g21.free.fr ([212.27.42.2]:43709 "EHLO smtp2-g21.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752650AbbGULlO (ORCPT ); Tue, 21 Jul 2015 07:41:14 -0400 Message-ID: <55AE2FD5.3000207@free.fr> Date: Tue, 21 Jul 2015 13:41:09 +0200 From: Mason User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0 SeaMonkey/2.32.1 MIME-Version: 1.0 To: stable@vger.kernel.org CC: LKML , Lukasz Majewski , Zhang Rui Subject: Requesting inclusion of 26bb0e9a in linux-3.14.y Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3038 Lines: 77 Hello, This is my first time requesting inclusion of a patch, please point out any breach of protocol. I'm using linux-3.14.y and I've run into a bug fixed in later kernel versions: commit 26bb0e9a1a938ec98ee07aa76533f1a711fba706 Author: Lukasz Majewski Date: Wed Sep 24 10:27:10 2014 +0200 thermal: step_wise: fix: Prevent from binary overflow when trend is dropping It turns out that some boards can have instance->lower greater than 0 and when thermal trend is dropping it results with next_target equal to -1. Since the next_target is defined as unsigned long it is interpreted as 0xFFFFFFFF and larger than instance->upper. As a result the next_target is set to instance->upper which ramps up to maximal cooling device target when the temperature is steadily decreasing. Signed-off-by: Lukasz Majewski Signed-off-by: Zhang Rui diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c index f251521baaa2..6705a0d746b3 100644 --- a/drivers/thermal/step_wise.c +++ b/drivers/thermal/step_wise.c @@ -76,7 +76,7 @@ static unsigned long get_target_state(struct thermal_instance *instance, next_target = instance->upper; break; case THERMAL_TREND_DROPPING: - if (cur_state == instance->lower) { + if (cur_state <= instance->lower) { if (!throttle) next_target = THERMAL_NO_TARGET; } else { Here's the debug output on my board: [ 21.301211] thermal thermal_zone0: last_temperature=0, current_temperature=51000 [ 21.308803] thermal thermal_zone0: Trip0[type=1,temp=70000]:trend=1,throttle=0 [ 21.316248] thermal cooling_device0: cur_state=0 [ 21.320957] thermal cooling_device0: old_target=-1, target=-1 [ 21.326755] thermal cooling_device0: zone0->target=4294967295 [ 21.332544] thermal cooling_device0: set to state 0 [ 34.349747] thermal thermal_zone0: last_temperature=51000, current_temperature=46000 [ 34.357830] thermal thermal_zone0: Trip0[type=1,temp=70000]:trend=2,throttle=0 [ 34.365254] thermal cooling_device0: cur_state=0 [ 34.369989] thermal cooling_device0: old_target=-1, target=4 [ 34.375740] thermal cooling_device0: zone0->target=4 [ 34.380867] thermal cooling_device0: set to state 4 Bug: raising the cooling state, despite the temperature dropping. The .bind() call was thermal_zone_bind_cooling_device(tz, 0, cdev, 4, 1); (The intent being that, once the system is above the trip temp, at least a little bit of cooling should be applied, always.) cur_state = 0 is not equal to lower_state = 1 AFAICT, Lukasz's patch fixes that issue. Regards. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/