[Bug 729944] [NEW] Flickering backlight on Thinkpad T400

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Binary package hint: xorg

My LED backlight flickers on a setting below 8 (min 0, max 15). On the
lowest setting, this is rather extreme from really off to maybe the
equivalent of ~3 to 4 within the fraction of a second. (I don't think
this is healthy for the display, especially on a non-LED based
backlight) The value of cat
/sys/class/backlight/acpi_video0/actual_brightness stays constant. As it
is so rapid and only visible in low-light conditions, it is impossible
for me to capture a video of it. Brightness level of 1 and above shows
less flickering, but still noticeable.

Another thing that might be related: Since about two weeks, the
brightness control via Fn+Brightness up/down changes the setting in
steps of 3, while it can be increased and decreased via cat or the KDE
battery monitor in single steps right now. Before that, step size via Fn
keys was also 1. A few days ago, I wasn't able to set the maximum level
(even with the control applet), but instead needed to reboot.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: xorg 1:7.6~3ubuntu11
ProcVersionSignature: Ubuntu 2.6.38-5.32-generic 2.6.38-rc6
Uname: Linux 2.6.38-5-generic x86_64
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: kwin
DRM.card0.DP.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes: 
 edid-base64:
DRM.card0.DP.2:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes: 
 edid-base64:
DRM.card0.DP.3:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes: 
 edid-base64:
DRM.card0.HDMI.A.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes: 
 edid-base64:
DRM.card0.HDMI.A.2:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes: 
 edid-base64:
DRM.card0.LVDS.1:
 status: connected
 enabled: enabled
 dpms: On
 modes: 1440x900 1440x900
 edid-base64: AP///////wAwrjZAAAAAAAASAQOAHhN46kuFkldWiiggUFQAAAABAQEBAQEBAQEBAQEBAQEBsCeggFGEGjAwIDYAML4QAAAZcCGgmFGEGjAwIDYAML4QAAAZAAAADwCVCjKVCigZGQAyDDwBAAAA/gBMUDE0MVdQMi1UTEIxAB8=
DRM.card0.VGA.1:
 status: disconnected
 enabled: disabled
 dpms: Off
 modes: 
 edid-base64:
Date: Sun Mar  6 00:51:33 2011
DistUpgraded: Log time: 2011-02-11 18:08:14.195705
DistroCodename: natty
DistroVariant: kubuntu
DkmsStatus:
 tp-smapi, 0.40, 2.6.35-25-generic-phc, x86_64: installed  (WARNING! Diff between built and installed module!) (WARNING! Diff between built and installed module!)
 tp-smapi, 0.40, 2.6.38-5-generic, x86_64: installed
GraphicsCard:
 Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) (prog-if 00 [VGA controller])
   Subsystem: Lenovo Device [17aa:20e4]
   Subsystem: Lenovo Device [17aa:20e4]
MachineType: LENOVO 6475VAT
ProcEnviron:
 LANGUAGE=
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-2.6.38-5-generic root=UUID=07994a0f-1d67-47e2-b6e8-ae65e7cfcf03 ro
Renderer: Unknown
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to natty on 2011-02-11 (22 days ago)
dmi.bios.date: 08/02/2010
dmi.bios.vendor: LENOVO
dmi.bios.version: 7UET89WW (3.19 )
dmi.board.name: 6475VAT
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:bvr7UET89WW(3.19):bd08/02/2010:svnLENOVO:pn6475VAT:pvrThinkPadT400:rvnLENOVO:rn6475VAT:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 6475VAT
dmi.product.version: ThinkPad T400
dmi.sys.vendor: LENOVO
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.23-1ubuntu3
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.1~git20110215.cc1636b6-0ubuntu2
version.xserver-xorg: xserver-xorg 1:7.6~3ubuntu11
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu2
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-4ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A

** Affects: meta-kde (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug kubuntu natty
-- 
Flickering backlight on Thinkpad T400
https://bugs.launchpad.net/bugs/729944
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