View source for How to make ACPI work on a ThinkPad T23

This page deals with installing and running {{Gentoo}} Linux (2005.1) on a ThinkPad {{T23}}, Model 2647-4MG.

==Basic installation==
The Linux kernel (2.6.12-r6) boots OK, and recognises all the devices (modem not tested).

==ACPI==
Getting software suspend working requires some tweaking.

First of all, [[BIOS Upgrade|update to the latest BIOS and Embedded Controller Program]].

{{cmdroot|dmesg}} will probably tell you that ACPI isn't enabled in the BIOS, because the T23 BIOS has no mention of ACPI. Just add {{bootparm|lapic|}} to the kernel
arguments in {{path|/etc/lilo.conf}} or {{path|/boot/grub/menu.lst}}.

After that, you will probably get a lot of ACPI error messages, generally of the form <tt>AE_NOT_EXIST</tt>. Those can be fixed by recompiling your DSTD. To do just that, get the Intel iasl compiler source from [http://developer.intel.com/technology/iapc/acpi/downloads.htm their site] and compile it.  It should build without troubles. De- and re-compile the DSDT. If it gives errors or remarks, try fixing them as best as you can or download final dsdt.dsl from [http://acpi.sourceforge.net/dsdt/view.php?id=758]. Then load the new DSDT on boot with the kernel's "Custom DSDT" option.

Now {{cmdroot|dmesg}} should show that the ACPI had found the ECDT and enabled the interpreter and you should find a full set of ACPI entries under {{path|/proc}}.

Done that, verify that the [[ibm-acpi]] driver is enabled by issuing {{cmdroot|ls /proc/acpi/ibm/*}}. If you see files in this directory, everything is alright. If the directory couldn't be found, you will have to enable [[ibm-acpi]] in your kernel config (as builtin or module) and recompile your kernel.

The next step is [[How to configure acpid|configuring acpid]], which handles the ACPI buttons through scripts in {{path|/etc/acpi}}.

To try if suspend to ram workd, press {{key|Fn}}{{key|F4}} or issue a {{cmdroot|echo -n mem >/sys/power/state}}.

===Resume problem===
If your system doesn't resume from sleep after that, use the power button to switch it off and restart. To solve the issue, try disabling S3 framebuffer support in your kernel config and recompile your kernel. Should that not be enough, try unloading suspicious drivers such as USB in your suspend script and reloading them on resume.

If all that doesn't help, build a monolithic kernel having everything you need builtin and only minimal options enabled. If it works with that kernel, start reenabling other options step by step.

===Button events===
By default, ACPI seems to handle three button events only - the Power button, the Suspend key ({{key|Fn}}{{key|F4}}) and the lid event. {{key|Fn}}{{key|F3}} (Screen blank) will need [[How to make ACPI work#Screen blanking (Standby)|extra configuration]], as well as {{key|Fn}}{{key|F12}} (Suspend to disk) (look [[How to make ACPI work#Suspend to disk (Hibernate)|here]]). {{key|Fn}}{{key|F7}}, (Switch to
video) at least blanks the LCD.

{{key|Fn}}{{key|Home}} (LED brighter), {{key|Fn}}{{key|End}} (LED dimmer), {{key|Fn}}{{key|PgUp}}
(Screen light) will work without any further effords, since they are not handled by the ACPI subsystem.

When the machine is running, the lid switch blanks the screen when
pressed and restores on release, but if the machine is suspended
pressing the switch does nothing and releasing it brings the machine out
of suspend mode.

Commands echoed to eg: {{path|/proc/acpi/ibm/light}} can be mixed with the appropriate keypresses (here,
{{key|Fn}}{{key|PgUp}}) without problems.

===Frequency Scaling===
The CPU (Pentium III-M) has power management and
throttling; use the '''acpi-cpufreq''' module instead of the '''speedstep-ich''' module to change speed automatically. The CPU has 
only two speeds, and with the '''cpufreq_ondemand''' & '''cpufreq_conservative''' modules, dynamic scaling will be achieved. Alternatively, with the '''speedstep-ich''' module, you can use a shell script to flip between the performance and powersave kernel governors; everything needed can be found in the {{path|/sys/devices/system/cpu/cpu0/cpufreq}} directory.

===UltraBay LED stays lit===
The Bay LED wrongly stays lit even when in suspend to ram mode, but the most recent (1.1) [[ibm-acpi]] module provides an ACPI LED device which controls most of the LEDs (the Bay LED
is 4), so you can switch it off in your suspend script.
{{WARN|The UltraBay LED should stay lit when suspended to RAM. Any ThinkPads newer than the 600X have hot-swappable UltraBays, not warm-swappable ones. Attempting to remove or insert an UltraBay device when suspended will cause it to wake up and try to handle the request, but with Linux this usually causes lockups.}}

===Resume===
With the CPU on low speed (if it matters) and the LED off the power consumption in Suspend mode is around 580mW.

It looks as if the software to control full ACPI functionality has
only stabilised within the middle of 2005, so if you
have problems, try upgrading to IBM's latest BIOS and EBIOS, and a
kernel >=2.12.  With luck, the next version or so of the S3 driver will
be free of its hang problem.

=External Sources=
*This guide is listed at the [http://tuxmobil.org/ibm.html TuxMobil Linux laptop and notebook installation survey (IBM/Lenovo)].