ACPI: manipulate trip_points om thermal_zone

[Christoph Bier <christoph.bier@web.de>]

Hello!

At the end of last week I brought my Laptop to my hardware dealer,
because it smelt burnt suddenly at the beginning of last week---but
without observing any impairment of functionality. My hardware
dealer couldn't find anything, but said, that my fan activates too
late. He observed activation not until 69°C; sometimes it starts up
at 63°C or 65°C with me, but I wouldn't contradict completely,
because his statement corresponds to the following output:

-----------------------------------------------------------
chris@skull:~$cat /proc/acpi/thermal_zone/THRM/trip_points
critical (S5):           101 C
passive:                 95 C: tc1=4 tc2=3 tsp=300 devices=0xcdfee760
active[0]:               70 C: devices=0xcdf213e0
------------------------------------------------------------

So I tried to manipulate the trip_points following
http://acpi.sourceforge.net/documentation/thermal.html:

-------------------------------------------------------------
root@skull:~#echo -n "101:0:90:60:0" > trip_points

chris@skull:~$cat /proc/acpi/thermal_zone/THRM/trip_points
critical (S5):           101 C
passive:                 90 C: tc1=4 tc2=3 tsp=300 devices=0xcdfee760
active[0]:               60 C: devices=0xcdf213e0
--------------------------------------------------------------

But nothing changes. Currently the CPU temperature is 65°C, but the
fan is standing still. Then I checked, whether I got a buggy DSDT
following http://forums.gentoo.org/viewtopic.php?t=122145 :

-------------------------------------------------------------------
root@skull:/tmp/DSDT#iasl -tc dsdt.dsl

Intel ACPI Component Architecture
ASL Optimizing Compiler / AML Disassembler version 20040715 [Aug 25
2004]
Copyright (C) 2000 - 2004 Intel Corporation
Supports ACPI Specification Revision 2.0c

ASL Input:  dsdt.dsl - 6419 lines, 189822 bytes, 1370 keywords
AML Output: DSDT.aml - 19846 bytes 452 named objects 918 executable
opcodes

Compilation complete. 0 Errors, 0 Warnings, 0 Remarks, 428 Optimizations
--------------------------------------------------------------------

Everything seems to be allright.

System information:
-------------------
- Laptop: IPC Power Note M 8375

- CPU:
chris@skull:~$fgrep "model name" /proc/cpuinfo
model name      : mobile AMD Athlon(tm) XP 2200+

- Kernel:
chris@skull:~$uname -rs
Linux 2.6.8.1

- Distribution: Debian Woody/Sarge

The output of
	dmesg -s40000
	dmidecode
	acpidmp
	lspci -vv
	cat /proc/interrupts
can be put on my home-webserver, if required.

My questions:
-------------
- are the default trip_points really too high?

- how can I manipulate the trip_points lasting and effective?

- is there a comprehensive description of ACPI in kernel 2.6 and
information how to the user can use resp. manage these features
(e.g. I still don't know, whether I need some tool to use PowerNow!
or whether the kernel controls it itself)?

Thanks for reading this long posting!

Best regards,
	Christoph