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SubjectRe: regression in linux 3.7 - fan speed at 100% after suspend/resume at 100%
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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.




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