How to make ACPI work on a ThinkPad T23

2006-01-26T10:56:27Z

UnixNut: /* ACPI */

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

==Basic installation==
The default 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. 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 IIIM) has power management but not
throttling, and doesn't at the moment change speed automatically.
There must be a way around this, but since the CPU has only two speeds
it's easier to 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 lid===
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.

===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.

How to make ACPI work on a ThinkPad T23

2006-01-26T02:03:43Z

UnixNut:

I recently bought a second-hand ThinkPad {{T23}}, Model 2647-4MG, and
decided to run {{Gentoo}} Linux 2.6.12-r6 on it; this is the 2005.1 release
on a DVD, since I have limited internet access.

The default kernel booted OK, and recognised all the devices (tho' I
haven't tested the modem, and I've run X-windows only briefly.)
However, I wanted software suspend, and I couldn't get that to work at
all.

The first complaint from dmesg was that ACPI wasn't enabled in the BIOS;
the T23 BIOS has no mention of ACPI, so I added lapic to the kernel
arguments and that went away. The next problem was a large number of
ACPI error messages, generally of the form <tt>AE_NOT_EXIST</tt>, so I got the
Intel iasl compiler source from their site and compiled it. It compiled
cleanly, and de-compiling and re-compiling the DSDT gave one Error and
one Remark. I fixed them as best I could, and loaded the new DSDT on
boot with the kernel's "Custom DSDT" option; this worked correctly, but
dmesg still showed a lot of ACPI error messages, including two which
said "Found ECDT" and "Could not use ECDT".

Rather than mess with the ECDT straightaway, I decided to upgrade to the
latest BIOS and Embedded Controller BIOS. The system came with (the
original) versions 1.12 and 1.04, so I downloaded versions 1.18 and
1.06a from the IBM Website. The installers come in floppy disk and
Windows-based versions, and I used them under Windows 2000. Mercifully
the re-flash worked as advertised, tho' interestingly the {{key|F12}} "Select
Boot Device" menu changed slightly, and at first it appeared to have
lost the "Boot from USB" option, although that was enabled in the BIOS.
Apparently the menu now simply calls a USB memory stick a hard drive.
Anyway, boot from USB still works.

Booting into Linux then gave me no error messages, and dmesg showed that
the ACPI had found the ECDT and enabled the interpreter. There was also
a full set of ACPI entries under {{path|/proc}}. Although the DSDT had changed,
de-compiling and re-compiling with iasl showed that the error that had
originally bothered me was still there, so I let it be. I then loaded
acpid, which handles the ACPI buttons through scripts in /etc/acpi.
Trying {{key|Fn}}{{key|F4}} to {{cmdroot|echo -n 3 >/proc/acpi/sleep}} suspended the system, but
nothing would bring it back. Fortunately the Power Off button was still
functional.

NOTE: On newer kernels (2.6.13 >) /proc/acpi/sleep has been superceaded by /sys/power/state, where state
can be either mem or standby (other options are available depending on system in question).
so to syspend to ram you would type "echo mem > /sys/poewr/state", and for standby you woudl type
"echo standby > /sys/power/state".

Digging around, it looked as if there were only three keys which ACPI
handled by default - the Power Off key, the Suspend key ({{key|Fn}}{{key|F4}}) and the
Lid key. I found that I had to provide a handler for the Suspend key,
but for simplicity I left the other two alone, and most other special
purpose keys, eg. {{key|Fn}}{{key|Home}} (LED brighter), {{key|Fn}}{{key|End}} (LED dimmer), {{key|Fn}}{{key|PgUp}}
(Screen light), kept on working anyway. {{key|Fn}}{{key|F3}} (Screen blank), didn't
work and nor (fortunately) did {{key|Fn}}{{key|F12}}, Suspend to disk; {{key|Fn}}{{key|F7}}, Switch to
video, seemed to - at least, it blanked the LCD. I then tried unloading
suspicious drivers such as USB, but could still only enter Suspend mode
and not recover; finally I built a kernel with no loadable modules
except networking, and the minimum of options - no USB, no PCMCIA,
nothing that wasn't actually present when the machine booted. That
finally worked, and I could suspend to disk with {{key|Fn}}{{key|F4}} and recover by
pressing Fn (but no other key - I seem to recall that any keypress would
work with the original BIOS).

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

I started re-enabling the various bits of hardware I needed one by one,
but when I re-enabled the Savage S3 framebuffer support the machine
would enter suspend, but would hang partway through re-emergence.

I then disabled the S3 stuff and enabled the Intel 830M framebuffer code
(I don't know how this relates to the S3 driver, but the T23 apparently
has both chips) and the suspend worked again. The S3 driver is handy in
text mode, since it gives more lines per screen (and a nice penguin logo
on boot-up) but the system still runs eg: X windows reasonably well.

Suspending and re-emerging with USB support and a USB memory key
plugged in, and with X windows running, then worked fine; at the
moment I don't have the hardware to test anything more. Some things
are still odd - the CPU (Pentium IIIM) has power management but not
throttling, and doesn't at the moment change speed automatically.
There must be a way around this, but since the CPU has only two speeds
it's easier to 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.

The Bay LED wrongly stays lit even when in suspend mode on battery
(unlike the Power LED), 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), and when my configuration has stabilised I'll set the LED up via
the suspend script. With the CPU on low speed (if it matters) and the
LED off the power consumption in Suspend mode is around 580mW.

I hope this helps someone else with their T23, because they are very
nice machines, and quite versatile; this one seems to be able to deal
with most forms of networking and mass storage pretty much out of the
box. It looks as if the software to control full ACPI functionality has
only stabilised within the last few months (ie: mid-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.

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How to make ACPI work on a ThinkPad T23

How to make ACPI work on a ThinkPad T23