Comment 0 for bug 919773

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 2 brightness levels) 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 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.

WORKAROUND:

Disable the kernel module by adding:

blacklist samsung_laptop

to : /etc/modprobe.d/blacklist.conf

OR use Voria's patch/PPA (links in the above mentioned bug).

[1] https://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=2d70b73ae5b85c9d13f5dfbb8fc4fd5edae633dc

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: linux-image-3.0.0-15-generic 3.0.0-15.25
ProcVersionSignature: Ubuntu 3.0.0-15.25-generic 3.0.13
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/controlC0: jami 1581 F.... pulseaudio
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:10ec0272,144dca00,00100001'
   Controls : 19
   Simple ctrls : 11
Date: Sat Jan 21 18:35:12 2012
EcryptfsInUse: Yes
HibernationDevice: RESUME=UUID=77010f3d-b94c-4718-8f0c-0324ea5ad852
InstallationMedia: Ubuntu-Netbook-Remix 9.10 "Karmic Koala" - Release i386 (20091028.4)
MachineType: SAMSUNG ELECTRONICS CO., LTD. NC10
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-15-generic root=UUID=af51795b-87a7-4268-b370-05a38dffd4b6 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.0.0-15-generic N/A
 linux-backports-modules-3.0.0-15-generic N/A
 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.M015.20090908.RHU
dmi.board.name: NC10
dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.board.version: Not Applicable
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD.
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvr11CA.M015.20090908.RHU:bd09/08/2009:svnSAMSUNGELECTRONICSCO.,LTD.:pnNC10:pvrNotApplicable:rvnSAMSUNGELECTRONICSCO.,LTD.:rnNC10:rvrNotApplicable:cvnSAMSUNGELECTRONICSCO.,LTD.:ct10:cvrN/A:
dmi.product.name: NC10
dmi.product.version: Not Applicable
dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD.