Public bug reported: 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: user 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. ** Affects: linux (Ubuntu) Importance: Undecided Status: Confirmed ** Tags: apport-bug bitesize hw-specific i386 kernel-graphics oneiric running-unity usability -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/919773 Title: The new (2.6.39+) samsung_laptop kernel module causes serious backlight flickering - makes the desktop unusable - part 2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/919773/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
