2013-03-03 00:23:06

by Ville Syrjälä

[permalink] [raw]
Subject: Re: regression in linux 3.7 - fan speed at 100% after suspend/resume at 100%

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.


2013-03-04 12:29:58

by Roberto Oppedisano

[permalink] [raw]
Subject: Re: regression in linux 3.7 - fan speed at 100% after suspend/resume at 100%

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).

2013-03-04 13:25:38

by Roberto Oppedisano

[permalink] [raw]
Subject: Re: regression in linux 3.7 - fan speed at 100% after suspend/resume at 100%

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).
>