IBM ThinkPad T42 ACPI suspend woes

[Jan Kokoska]

On Sun, 2004-10-10 at 18:10 -0400, Tim Hull wrote:
> I've installed Ubuntu on my IBM ThinkPad T42.  I was pleasantly
> surprised to get everything working easily (including wi-fi, which was
> super easy with my intel 2200 wireless).  However, ACPI has some 
> problems.  While speedstepping and laptop-mode work great, suspend has 
> some problems.  I made a script to use ACPI suspend when I close the lid 
> of my laptop (in the /etc/acpi directory).  I unload the ehci_hcd 
> module, unload my winmodem modules, and then put it into sleep with this 
> script (restarting the things that were stopped upon resume).
> 
>  The system goes into sleep easily when I close the lid, however, it uses
> 10% of my battery for each hour that I leave my laptop in suspend, which 
> is way too much (in Windows it barely uses anything).  APM works and 
> doesn't use 10% of my battery per hour in suspend, but the laptop gets 
> very hot in APM, as speedstep doesn't work.  Does anyone have any 
> suggestions to fix this problem with ACPI?

Yes. Instead of suspend to memory that you are using right now (and
which is really a compromise between resume period and actual power
savings), use suspend to disk.

I am afraid the procedure I was most happy with in the end involved
pathcing 2.6.8 kernel with new ACPI [0] and swsusp2 [1] and also special
key module for thinkpads [2].

Linux suspend to disk is a bit of hack and it took a while to get it
properly working (swsusp and pmdisk in standard kernel don't work too
well, at least for me). Wake-up is in fact partial boot where swsusp2
code takes over after ACPI initialization. Pretty fast, though.

My Thinkpad R40
------------------------------------------
suspend 	suspend/resume	battery
method		time		duration
------------------------------------------
mem 		3s/10s		10-15 hours
disk		10s/30s		unlimited

Regards,
Jan

[0] http://acpi.sourceforge.net/
[1] http://softwaresuspend.berlios.de/
[2] http://ibm-acpi.sourceforge.net/