Re: regression in linux 3.7 - fan speed at 100% after suspend/resumeat 100%

[Roberto Oppedisano]

Added Cc: list

Il 04/03/2013 13:29, Roberto Oppedisano ha scritto:
> 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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