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SubjectRe: Fans at full speed after resume
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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
> 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@intel.com>
> AuthorDate: Tue Oct 9 01:35:52 2012 -0400
> Commit: Len Brown <len.brown@intel.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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