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    SubjectRe: [lm-sensors] 3.13.?: Strange / dangerous fan policy...
    On 03/08/2014 03:08 AM, Jean Delvare wrote:
    > On Fri, 7 Mar 2014 14:52:30 -0800, Guenter Roeck wrote:
    >> On Fri, Mar 07, 2014 at 11:04:29PM +0100, Manuel Krause wrote:
    >>> Hi, and thanks for the quick response!
    >>> No special fancy "fan control policy". 'fancontrol' isn't up or
    >>> running.
    >>> Vanilla kernels 3.11.* and 3.12.* had been working on here without
    >>> any extra work.
    >>> --
    >>> # sensors
    >>> acpitz-virtual-0
    >>> Adapter: Virtual device
    >>> temp1: +71.0°C (crit = +256.0°C)
    >>> temp2: +69.0°C (crit = +110.0°C)
    >>> temp3: +52.0°C (crit = +105.0°C)
    >>> temp4: +25.0°C (crit = +110.0°C)
    >>> temp5: +58.0°C (crit = +110.0°C)
    >>>
    >>> coretemp-isa-0000
    >>> Adapter: ISA adapter
    >>> Core 0: +62.0°C (high = +105.0°C, crit = +105.0°C)
    >>> Core 1: +60.0°C (high = +105.0°C, crit = +105.0°C)
    >>> --
    >>> My notebook (HP/Compaq 6730b) does not have a seperate fan sensor.
    >>> This is with 3.12.13 with my normal workload.
    >>>
    >>> Please, trust my above mentionned values of 94 °C vs. 74°C as I
    >>> don't like to boot 3.13.6 anymore, to avoid harm to the notebook's
    >>> casing.
    >>
    >> Understood. Unfortunately, we'll need to get information
    >> from the new kernel to be able to track down the problem.
    >
    > Indeed. Not only the run-time temperatures, but also the high and crit
    > limits.
    >
    >>> But I'd do to test any improvement-patch.
    >>
    >> So far I have no idea what is going on. I don't see anything in the
    >> drivers providing above data that would explain the behavior,
    >> but I might be missing something.
    >
    > Looks like a regression in the acpi subsystem or in power management,
    > not hwmon. Hwmon is merely reporting the temperatures, it's not
    > responsible for the actual temperatures.
    >

    I would agree. I don't think we have enough information to be sure,
    though. There might be some unintended interaction or interference.

    gpu is a good hint ... for example, look at commit b9ed919f1c8
    (drm/nouveau/drm/pm: remove everything except the hwmon interfaces
    to THERM). nouveau does export pwm and fan control information,
    so any change in that code may have unintended side effects.
    Similar, I don't know how ec39f64bba (drm/radeon/dpm: Convert to
    use devm_hwmon_register_with_groups) could have the observed impact,
    as it is purely passive, but I prefer to be rather safe than sorry.

    This problem has now been submitted into bugzilla as
    https://bugzilla.kernel.org/show_bug.cgi?id=71711.

    Guenter

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