Ubuntu – High fan speed after return from suspend (on Ubuntu)

fanlaptopsuspendUbuntuubuntu-10.04

I've got a HP ProBook 5310m laptop with Ubuntu 10.04 (32 bit). When I return from suspend, the fan speed is usually very high: FDTZ sensor reports "90 °C". Yes, the units are wrong, since FDTZ does not report temperature, but fan speed – that's probably just a small bug in reporting. Interestingly, when I plug or unplug the power cable for a moment, the fan speed returns back to normal.

My questions:

Where can I report this problem? Is it about ACPI support in the kernel? What is the address of the relevant bug tracker?
As a workaround for now, how can I programmatically trigger a behavior equivalent to (un)plugging the power cable. More generally, how can I force ACPI to recalculate fan speed? Ideally, I'm looking for something like echo foo > /proc/bar.

Thanks in advance!

Best Answer

In my case, a workaround for now is to issue this command after suspend (as root):

echo 0 > /proc/acpi/fan/FAN5/state

This command switches on a device – sets its power state to D0. Apparently, it can also be used to "reset" a fan that is already on. After that operation, the fan runs at normal speed (30 °C). How did I know which fan to touch? I looked for a fan with "on" status:

grep on /proc/acpi/fan/*/state

It seems that a fairly similar issue has already been added to the Kernel Bug Tracker.

Related Solutions

Linux – Ubuntu/Toshiba Fan Speed Issue

This is a known bug in Ubuntu, dating back to 2006 :
Bug #77370 : Laptop Fan always on after resume from suspend to RAM.

The above is a very long thread going on for 6 years, concluding that this problem happens on some kernel versions, but not on all.

Some solutions were listed, going from unplug/replug the power cord to creating a script to run after resume to stop the fan.

The script in question is created as file /etc/pm/sleep.d/99fancontrol (remember to chmod 755) :

#!/bin/sh
#
# Stop the fan.
# Source: https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.17/+bug/77370

case "$1" in
 hibernate|suspend)
  # Stopping is not required.
  ;;
 thaw|resume)
# In background.
   ( sleep 10 ; echo -n "0" > /sys/devices/virtual/thermal/cooling_device1/cur_state ) &

  ;;
 *) exit $NA
  ;;
esac

Linux – How to run commands on suspend/return from suspend

From manpage pm-action(8):

/etc/pm/sleep.d, /usr/lib/pm-utils/sleep.d
     Programs in these directories (called hooks) are combined
     and executed in C sort order before suspend and hibernate
     with as argument ´suspend´ or ´hibernate´. Afterwards they
     are called in reverse order with argument ´resume´ and
     ´thaw´ respectively. If both directories contain a similar
     named file, the one in /etc/pm/sleep.d will get preference.
     It is possible to disable a hook in the distribution
     directory by putting a non-executable file in
     /etc/pm/sleep.d, or by adding it to the HOOK_BLACKLIST
     configuration variable.

Thus you could simply put a shell-script like this:

#!/bin/bash

case "$1" in
suspend|hibernate)
    actions to
    take
    on suspend
    or hibernate
    ;;
resume|thaw)
    other actions
    to trigger
    on resume
    ;;
esac

into e.g. 99-myhooks.sh and make it executable.

BTW, you can kill stale SSH-connections by entering Enter~.Enter in the SSH session.

Best Answer

Related Solutions

Linux – Ubuntu/Toshiba Fan Speed Issue

Linux – How to run commands on suspend/return from suspend

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