From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vladimir Zajac Subject: Re: PROBLEM: (regression) thermal zone - fan is turned on at higher temperature than it should Date: Wed, 6 May 2009 07:50:21 +0200 Message-ID: <200905060750.21416.eightgraph@gmail.com> References: <200905052105.07316.eightgraph@gmail.com> <1241570812.3773.72.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from fg-out-1718.google.com ([72.14.220.153]:47442 "EHLO fg-out-1718.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750789AbZEFFuX (ORCPT ); Wed, 6 May 2009 01:50:23 -0400 Received: by fg-out-1718.google.com with SMTP id 16so1619588fgg.17 for ; Tue, 05 May 2009 22:50:22 -0700 (PDT) In-Reply-To: <1241570812.3773.72.camel@localhost.localdomain> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: yakui_zhao Cc: "linux-acpi@vger.kernel.org" On Wednesday 06 May 2009 02:46:52 you wrote: > On Wed, 2009-05-06 at 03:05 +0800, Vladimir Zajac wrote: > > [1.] One line summary of the problem: > > (regression) thermal zone - fan is turned on at higher temperature than it should > > > > [2.] Full description of the problem/report: > > After upgrade to 2.6.30-rc4 I noticed that my laptop's fan sometimes runs at lower speed than it used to. > > 2.6.29 does not have the bug. > > > > The laptop (HP Compaq 6710b) has 5 ACPI cooling devices which correspond to different fan speeds. They are not turned on when I expect them to be. > > > > Expected behavior: > > Each active cooling device should be turned on when current temperature is equal or higher than its trip point. > > (This is how it worked in 2.6.29 and earlier versions and also how it is defined by ACPI specification.) > > > > Actual behavior in 2.6.30-rc4: > > Each cooling device is turned on only when current temperature is strictly greater than the corresponding trip point but not when current temperature is equal to the trip point. > > > > It is caused by commit b1569e99c795bf83b4ddf41c4f1c42761ab7f75e: > > > > author Matthew Garrett > > Wed, 3 Dec 2008 17:55:32 +0000 (17:55 +0000) > > committer Len Brown > > Fri, 20 Feb 2009 23:41:56 +0000 (18:41 -0500) > > commit b1569e99c795bf83b4ddf41c4f1c42761ab7f75e > > ACPI: move thermal trip handling to generic thermal layer > > > > > > This commit (probably unintentionally) also changed how kernel determines if a cooling device has to be activated: > > before the commit: cooling device is activated if current temperature >= trip point temperature > > after the commit: cooling device is activated if current temperature > trip point temperature > Do you mean that the issue can be fixed by changing the "temperature > > trip point" to "temperature >= trip point"? > If so, what you have done is reasonable. > > Thanks. Yes, it can be fixed by changing the "temperature > trip point" to "temperature >= trip point". > > > > I tried to change the trip point test back to "temp >= trip_temp" in drivers/thermal/termal_sys.c (attached patch). It fixes the issue on my laptop. > > > > [3.] Keywords (i.e., modules, networking, kernel): > > acpi, thermal zone > > > > [4.] Kernel information > > [4.1.] Kernel version (from /proc/version): > > Linux version 2.6.30-rc4-64v01kms (root@V2G64) (gcc version 4.3.2 (Gentoo 4.3.2-r3 p1.6, pie-10.1.5) ) #2 SMP PREEMPT Fri May 1 00:11:41 CEST 2009 > > > > [5.] Most recent kernel version which did not have the bug: > > 2.6.29 > > > > [X.] Other notes, patches, fixes, workarounds: > > > > patch which should fix the issue(for 2.6.30-rc4): > > > > --- linux-2.6.30-rc4/drivers/thermal/thermal_sys.c 2009-04-30 23:52:59.000000000 +0200 > > +++ linux-2.6.30-rc4-p1/drivers/thermal/thermal_sys.c 2009-05-04 19:58:30.000000000 +0200 > > @@ -961,7 +961,7 @@ void thermal_zone_device_update(struct t > > > > switch (trip_type) { > > case THERMAL_TRIP_CRITICAL: > > - if (temp > trip_temp) { > > + if (temp >= trip_temp) { > > if (tz->ops->notify) > > ret = tz->ops->notify(tz, count, > > trip_type); > > @@ -974,7 +974,7 @@ void thermal_zone_device_update(struct t > > } > > break; > > case THERMAL_TRIP_HOT: > > - if (temp > trip_temp) > > + if (temp >= trip_temp) > > if (tz->ops->notify) > > tz->ops->notify(tz, count, trip_type); > > break; > > @@ -986,14 +986,14 @@ void thermal_zone_device_update(struct t > > > > cdev = instance->cdev; > > > > - if (temp > trip_temp) > > + if (temp >= trip_temp) > > cdev->ops->set_cur_state(cdev, 1); > > else > > cdev->ops->set_cur_state(cdev, 0); > > } > > break; > > case THERMAL_TRIP_PASSIVE: > > - if (temp > trip_temp || tz->passive) > > + if (temp >= trip_temp || tz->passive) > > thermal_zone_device_passive(tz, temp, > > trip_temp, count); > > break; > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-acpi" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > >