Bug#640293: Presario A975 EM: fan runs at a constant (low) speed after hibernate, until it starts to overheat

[Philip Ashmore <contact@philipashmore.com>]

On 15/02/12 19:33, Jonathan Nieder wrote:
> Hi Philip,
>
> Philip Ashmore wrote:
>
> > The thing is, when my laptop resumes from hibernate:
> > The fan runs at a constant audible low speed.
> > Usually the fan is so quiet it's inaudible when the cpu is idle, but after
> > hibernate I know something's up.
> >
> > artsd pops up a message box - cpu overload, aborting.
> >
> > When I run something that taxes one or both cores, the fan speed doesn't
> > increase, but a couple of minutes in the fan will suddenly jump to full
> > "emergency vent" mode and the plastic casing near the vent is almost too hot
> > to touch.
>
> I think our best bet for solving this is to get help from upstream.
>
> Please test 3.2.4-1 from unstable or newer, and if it reproduces the
> bug, file a report at<http://bugzilla.kernel.org/>, product ACPI,
> component Power-Fan and let us know the bug number so we can track it.
>
> Be sure to attach output from "acpidump", "grep .  /sys/class/thermal/*/*"
> before and after hibernating, and "dmesg" after hibernating (as
> separate attachments, uncompressed).
>
> Compare<https://bugzilla.kernel.org/show_bug.cgi?id=19452>.
>
> Thanks and hope that helps,
> Jonathan
Just as a last check after upgrading to 3.2.4-1 and 
hibernating/resuming, I ran "sensors"
from the lm-sensors package.
It reported this:
  acpitz-virtual-0
  Adapter: Virtual device
  temp1:        +55.0°C  (crit = +100.0°C)

even though I was running both cores at 100% for a few minutes.

It looks like the PC doesn't know it's overheating.

I decided not to wait for the "emergency vent" I reported before to kick in.

I rebooted and "sensors" reported:
   acpitz-virtual-0
   Adapter: Virtual device
   temp1:        +71.0°C  (crit = +100.0°C)

After a minute or so the fan kicked in a bit more and the temperature 
reduced gradually
to 48C.
It looks like the temperature sensor has a resolution of 7-8 degrees.

Does this help or should I still report it upstream?

Regards,
Philip Ashmore