LCD Brightness buttons do not work on ThinkPad R61/T61/X61

Bug #172985 reported by pullin on 2007-11-30
Affects Status Importance Assigned to Milestone
Nominated for Hardy by Serge

Bug Description

Brightness up and down buttons (Fn + Home, Fn + End) don't work.
Running kubuntu, gutsy 7.10.
acpid catches events fine, and invokes /etc/acpi/ and /etc/acpi/

The scripts there run acpi_fakekey 224 or 225 , which doesn't seem to do anything.

Changing these to:
echo 4 > /proc/apci/ibm/cmos
echo 5 > /proc/acpi/ibm/cmos

Fixes the problem, although it may just be a bandaid. Shouldn't acpi_fakekey work?


Carlos Perelló Marín (carlos) wrote :

This is not KDE specific, the same happens with gnome

Carlos Perelló Marín (carlos) wrote :

I forgot to mention that it happens in my Thinkpad X61s.

pullin (pullin) wrote :

Does the fix work? Seems pretty straightforward & important, it'd be good to get it committed...

Jerone Young (jerone) wrote :

This is not a proper fix .. but a hack around the real issue. This also does not give the various brightness levels. This is not a good fix.

tyler (tyler-chickn) wrote :

My problem seemed to be because I was missing '/usr/share/acpi-support', which is provided by the package 'acpi-support'.

apt-get install acpi-support

and you should be good to go.

tyler (tyler-chickn) wrote :

Yea, acpi_fakekey is in 'acpi-support' as well, if you don't have that installed yer not gonna get very far. ;)

pullin (pullin) wrote :

I know it it is a pretty miserable fix, but:

1) I seem to get all the various brightness levels with this modifications on my X61 Tablet, model 7764-CTO
2) acpi-support is installed; I can run acpi_fakekey, but acpi_fakekey 224 or 225 does nothing, and does not generate any entries in /var/log/acpid

Ryan Sinn (ryan-sinn) wrote :

This is still an issue with Hardy... I did some reading and apparently the ACPI issue is due to Ubuntu developers messing around with Thinkpad ACPI calls / keys. The Thinkpad ACPI developer specific wrote about this (I'll try to find the link) and how this is a bad idea.

Jerone Young (jerone) wrote :

acpi fake key does not generate an acpi event. It generates a keyboard event. Now brightness is still broken in hardy and it is being worked. But using the thinkpad-acpi interface to change the brightness instead of the (currently broken) acpi interface is not recommended in the thinkpad-acpi notes.

KillerKiwi (killerkiwi2005) wrote :

I can adjust brightness on my r61, it actually hangs X if i try to move the brightness applet up or down

See for lots of useful info that might be related. I have a T61 that I got working thusly.

It started to work again in my X61 laptop with GNOME and latest packages from Hardy.

Ryan Sinn (ryan-sinn) wrote :

Working here too.

KillerKiwi (killerkiwi2005) wrote :

Works now!

pullin (pullin) wrote :

Confirmed to work on X61 Tablet. Thanks to whoever fixed it!

Սահակ (petrosyan) wrote :

Does anybody also notices that the brightness goes down two times faster than it goes up?
I am seeing this on X61.

Fredrik Wendt (fredrik-wendt) wrote :

Ani: On my T61 the brightness always takes two steps, no matter if it's up or down (brighter/darker).

Kyle Lee (shrednine) wrote :

Works fine now on my T61 (Intel video).

thinkpad-acpi module causes a seconed event (sudo acpi_liste), you could disable the brightness events while doing:
sudo -s
echo 0xfF00FFF > /proc/acpi/ibm/hotkey

Remember: after every reboot hotkey-setup echos another mask into hotkey

if you want to hack further stop hotkey-setup from doing this or file a bug against hotkey-setup


status: enabled
mask: 0x00ffffff
commands: enable, disable, reset, <mask>

should i change it to 0xfF00FFF ?

Distributor ID: Ubuntu
Description: Ubuntu intrepid (development branch)
Release: 8.10
Codename: intrepid

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