linux-kernel - Re: Fans at full speed after resume

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Date:	Wed, 15 May 2013 12:29:53 +0800
From:	Zhang Rui <rui.zhang@...el.com>
To:	Sonny Rao <sonnyrao@...omium.org>
Cc:	linux-pm@...r.kernel.org, Sameer Nanda <snanda@...omium.org>,
	"Triplett, Josh" <josh.triplett@...el.com>,
	Olof <olofj@...omium.org>, len.brown@...el.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: Fans at full speed after resume

On Wed, 2013-05-15 at 12:26 +0800, Zhang Rui wrote:
> please
> 
> On Tue, 2013-05-14 at 21:18 -0700, Sonny Rao wrote:
> > Hi, I've seen a regression in kernels since 3.7 on x86 devices where
> > the kernel turns the system fans on to max speed after resuming from
> > ram.  Other people have noticed it as well, for example see
> > https://bugzilla.redhat.com/show_bug.cgi?id=895276
> > 
> please check if this is a duplicate of bug
> https://bugzilla.kernel.org/show_bug.cgi?id=56591
or you can try 3.10-rc1 to see if the problem still exists or not.

thanks,
rui
> > For example on the Samsung 550 Chromebook, we have one thermal zone
> > and have 5 cooling_devices, 0-4, which correspond to 5 possible fan
> > speeds.  Under typical idle, only cooling_device4 and maybe
> > cooling_device3 are active, depending on temperature:
> > 
> > cat /sys/class/thermal/cooling_device[01234]/cur_state
> > /sys/class/thermal/thermal_zone0/temp
> > 0
> > 0
> > 0
> > 0
> > 1
> > 57000
> > 
> > however after a suspend/resume, we see that cooling_devices 0 and 1
> > become active:
> > cat /sys/class/thermal/cooling_device[01234]/cur_state
> > /sys/class/thermal/thermal_zone0/temp
> > 1
> > 1
> > 0
> > 0
> > 1
> > 54000
> > 
> > and it seems to stay that way, even though the temperature is low
> > enough that the fan shouldn't be running at that speed.  If I manually
> > disable cooling_devices 0 and 1 then fan control works normally again.
> > 
> > I started bisecting it and was able to do so up until this commit:
> > commit 29b19e250434c6193c8b8e4c34c9c6284dd4f101
> > Merge: 125c4c7 c072fed
> > Author:     Len Brown <len.brown@...el.com>
> > AuthorDate: Tue Oct 9 01:35:52 2012 -0400
> > Commit:     Len Brown <len.brown@...el.com>
> > CommitDate: Tue Oct 9 01:35:52 2012 -0400
> > 
> >     Merge branch 'release' of
> > git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux into
> > thermal
> > 
> > unfortunately, I'm not able to successfully do a suspend/resume on the
> > commits in that merge, so I wasn't able to bisect down to the exact
> > commit.
> > 
> > I did confirm that one parent of the merge is okay: commit
> > 125c4c706b680c7831f0966ff873c1ad0354ec25 idr: rename MAX_LEVEL to
> > MAX_IDR_LEVEL
> > 
> > so I think it falls somewhere in this list of commits:
> > c072fed95c9855a920c114d7fa3351f0f54ea06e...e3f25e6e5836c4790fbe395ff42e241f372d859d
> > 
> > c072fed9 thermal: Exynos: Fix NULL pointer dereference in
> > exynos_unregister_thermal()
> > a4b6fec9 Thermal: Fix bug on cpu_cooling, cooling device's id conflict problem.
> > 79e093c3 thermal: exynos: Use devm_* functions
> > 17be868e ARM: exynos: add thermal sensor driver platform data support
> > 7e0b55e6 thermal: exynos: register the tmu sensor with the kernel thermal layer
> > f22d9c03c thermal: exynos5: add exynos5250 thermal sensor driver support
> > c48cbba6 hwmon: exynos4: move thermal sensor driver to driver/thermal directory
> > 02361418 thermal: add generic cpufreq cooling implementation
> > a7a3b8c8 Fix a build error.
> > 204dd1d3 thermal: Fix potential NULL pointer accesses
> > 1e426ffdd thermal: add Renesas R-Car thermal sensor support
> > 79a49168 thermal: fix potential out-of-bounds memory access
> > f4a821ce6 Thermal: Introduce locking for cdev.thermal_instances list.
> > 908b9fb79 Thermal: Unify the code for both active and passive cooling
> > ce119f832 Thermal: Introduce simple arbitrator for setting device cooling state
> > b5e4ae62 Thermal: List thermal_instance in thermal_cooling_device.
> > cddf31b3b Thermal: Rename thermal_instance.node to thermal_instance.tz_node.
> > 2d374139 Thermal: Rename thermal_zone_device.cooling_devices
> > b81b6ba3 Thermal: rename structure thermal_cooling_device_instance to
> > thermal_instance
> > 4ae46befb Thermal: Introduce thermal_zone_trip_update()
> > 1b7ddb84 Thermal: Remove tc1/tc2 in generic thermal layer.
> > 601f3d424 Thermal: Introduce .get_trend() callback.
> > 9d99842f9 Thermal: set upper and lower limits
> > 74051ba5 Thermal: Introduce cooling states range support
> > 
> > When I get time, I'll try to rebase those commits onto the IDR commit
> > and see if I can get a better bisect.  Any insights into the problem
> > would be appreciated, thanks.
> 
> 
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