I was using a 10.10 Ubuntu Wubi installation on a Lenovo Thinkpad X200, the issue was not present at this time. Kernel at this time 2.6.35. After a dist-upgrade via "update-manager -d" the following problem occured.
By default the screen brightness is very low, even the highest brightness setting available via thinkpad hotkeys (working!) is to low to work comfortable. The lowest setting almost turns of the backlight all together.
Workaround:
$ sudo bash -c "echo 4 > /proc/acpi/ibm/cmos"
This sets the increases the brightness scale available via the hotkeys and instantly increases the brightness of the backlight.
ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: linux-image-2.6.38-6-generic-pae 2.6.38-6.34
Regression: Yes
Reproducible: Yes
ProcVersionSignature: Ubuntu 2.6.38-6.34-generic-pae 2.6.38-rc7
Uname: Linux 2.6.38-6-generic-pae i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: i386
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: CONEXANT Analog [CONEXANT Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: florian 1648 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
Card hw:0 'Intel'/'HDA Intel at 0xf2620000 irq 47'
Mixer name : 'Conexant CX20561 (Hermosa)'
Components : 'HDA:14f15051,17aa20ff,00100000'
Controls : 16
Simple ctrls : 8
Card29.Amixer.info:
Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw 7XHT22WW-1.04'
Mixer name : 'ThinkPad EC 7XHT22WW-1.04'
Components : ''
Controls : 1
Simple ctrls : 1
Card29.Amixer.values:
Simple mixer control 'Console',0
Capabilities: pswitch pswitch-joined penum
Playback channels: Mono
Mono: Playback [on]
Date: Sat Mar 12 03:41:39 2011
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release i386 (20101007)
MachineType: LENOVO 7454CTO
ProcEnviron:
LANGUAGE=en_US:en
PATH=(custom, user)
LANG=en_US.UTF-8
SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-6-generic-pae root=UUID=DAA444ABA4448C47 loop=/ubuntu/disks/root.disk ro quiet splash
RelatedPackageVersions:
linux-restricted-modules-2.6.38-6-generic-pae N/A
linux-backports-modules-2.6.38-6-generic-pae N/A
linux-firmware 1.48
SourcePackage: linux
UpgradeStatus: Upgraded to natty on 2011-03-12 (0 days ago)
dmi.bios.date: 05/18/2009
dmi.bios.vendor: LENOVO
dmi.bios.version: 6DET53WW (3.03 )
dmi.board.name: 7454CTO
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr6DET53WW(3.03):bd05/18/2009:svnLENOVO:pn7454CTO:pvrThinkPadX200:rvnLENOVO:rn7454CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 7454CTO
dmi.product.version: ThinkPad X200
dmi.sys.vendor: LENOVO
with natty release and recent updates this bug seems to be resolved.