The new (2.6.39+) samsung_laptop kernel module causes serious backlight flickering - makes the desktop unusable - part 2
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
Linux |
Fix Released
|
Medium
|
|||
linux (Ubuntu) |
Fix Released
|
Medium
|
Unassigned |
Bug Description
This bug is fixed in upstream's Linux 3.4.0-030400-
dmesg | grep samsung
[ 19.490347] samsung_laptop: detected SABI interface: SwSmi@
[ 19.490358] samsung_laptop: Backlight controlled by ACPI video driver
--> No flickering!
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This is a continuation from bug 810093 but I'm using Samsung NC10. The backlight of the laptop often starts flickering (switching very fast between darkest and brightest) when gnome tries to reduce the screen brightness (automatically after some time) to save power.
This bug is caused by the new samsung_laptop kernel module which was introduced in kernel 2.6.39. I've found some documentation for it at github [1]. If the module is enabled, the flickering starts quite soon after desktop load and can be stopped by changing the baclight brigtness. However, the only available modes are 0%, 10%(estimate) and 100%. The two lowest values are too dark for my eyes and the full backlight uses too much battery power.
The main difference from bug 810093 is that this issue doesn't occur on every boot but maybe on 80% of boots.
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WORKAROUND:
Disable the kernel module by adding:
blacklist samsung_laptop
to : /etc/modprobe.
OR use the upstream v3.4. kernel (Precise only), please note that they're unsupported:
http://
OR use Voria's patch/PPA (links in the above mentioned bug).
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ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: linux-image-
ProcVersionSign
Uname: Linux 3.0.0-15-generic i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices:
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC272 Analog [ALC272 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
ApportVersion: 1.23-0ubuntu4
Architecture: i386
ArecordDevices:
**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC272 Analog [ALC272 Analog]
Subdevices: 1/1
Subdevice #0: subdevice #0
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/
CRDA: Error: [Errno 2] Tiedostoa tai hakemistoa ei ole
Card0.Amixer.info:
Card hw:0 'Intel'/'HDA Intel at 0xf0340000 irq 43'
Mixer name : 'Realtek ALC272'
Components : 'HDA:10ec0272,
Controls : 19
Simple ctrls : 11
Date: Sat Jan 21 18:35:12 2012
EcryptfsInUse: Yes
HibernationDevice: RESUME=
InstallationMedia: Ubuntu-
MachineType: SAMSUNG ELECTRONICS CO., LTD. NC10
ProcKernelCmdLine: BOOT_IMAGE=
RelatedPackageV
linux-
linux-
linux-firmware 1.60
SourcePackage: linux
UpgradeStatus: Upgraded to oneiric on 2011-10-01 (112 days ago)
dmi.bios.date: 09/08/2009
dmi.bios.vendor: Phoenix Technologies Ltd.
dmi.bios.version: 11CA.M015.
dmi.board.name: NC10
dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.board.version: Not Applicable
dmi.chassis.
dmi.chassis.type: 10
dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.chassis.
dmi.modalias: dmi:bvnPhoenixT
dmi.product.name: NC10
dmi.product.
dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD.
Changed in linux (Ubuntu): | |
status: | New → Confirmed |
tags: | added: precise |
Changed in linux (Ubuntu): | |
status: | Incomplete → Confirmed |
Changed in linux (Ubuntu): | |
importance: | Undecided → Medium |
Changed in linux: | |
importance: | Unknown → Medium |
status: | Unknown → Confirmed |
tags: |
added: kernel-fixed-upstream kernel-fixed-upstream-3.4.0-030400 removed: kernel-bug-exists-upstream |
description: | updated |
Changed in linux: | |
status: | Confirmed → Fix Released |
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