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Message-ID: <513493C1.6070206@gmail.com>
Date: Mon, 04 Mar 2013 13:29:53 +0100
From: Roberto Oppedisano <roberto.oppedisano@gmail.com>
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To: linux-kernel@vger.kernel.org
CC: Ville Syrjala <syrjala@sci.fi>
Subject: Re: regression in linux 3.7 - fan speed at 100% after suspend/resume
 at 100%
References: <50BDF345.60804@gmail.com> <loom.20130303T010825-770@post.gmane.org>
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Il 03/03/2013 01:22, Ville Syrjala ha scritto:
> Roberto Oppedisano <roberto.oppedisano <at> gmail.com> writes:
>
>> Hello,
>>       with recent kernels after a suspend/resume cycle on my laptop (HP
>> 6730b) the fans stays at full speed.
> I too have been hit by this regression w/ a HP Compaq NC6000 laptop.
>
> >From what I can tell 3.7.x gets confused about trip points after resume. Based
> on the information in sysfs, it seems to always think that the CPU temp > 65C,
> when in fact it's usually 40C or so. Loading the CPU enough to rise the
> temperature past the trip point where the kernel thinks we're at seems to
> re-synchronize the kernel's reality with the firmware's reality. On a few
> occasions however the fan did stop, but the trip points were still confused the
> same way. So what happened is that the fan didn't come back to life until I hit
> the next higher trip point at 80C. Under normal conditions I've never reached
> the 80C trip point on this laptop.
>
> I also tried this tree:
> git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux.git next
> $ git describe
> v3.8-rc2-72-gf5b6d45
>
> Sadly I must report that it's even worse than 3.7. Even without any
> suspend/resume cycles, the system gets confused. When I heat up the CPU the fan
> comes on correctly and speeds up as the temperature rises. Unfortunately when
> the temperature drops the fan doesn't slow down at all. So once I hit a high
> trip point the fan stays at that speed forever.

I'm running now with:

$ git describe
v3.9-rc1

and it seem that the behaviour of my laptop is similar to yours.
Also, immediately after a suspend/resume cycle, the fan speed goes down,
and again the speeds correctly goes up as the temperature rises, but when
the temperature drops the fan doesn't slow.

Now the suspend/resume cycle seems almost unrelated with the issue 
(except for
the fan speed reset at resume).

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