Public bug reported: After upgrading to 3.5.0-15 on Quantal my Samsung 900X4C boots with it's display backlight off.
The backlight is turned off immediately after grub and before the kernel messages start. The display remains off and the keyboard keys assigned to adjust the brightness do not change the display. The previous kernel (3.5.0-14) does not display these symptoms. Workarounds: 1) Create a script which runs at boot time to turn the display on. I do this by running a reboot cronjob to set the display brightness. /etc/cron.d/fix-backlight: @reboot root echo 2040 > /sys/class/backlight/intel_backlight/brightness A initscript would be able to do the job as well, or better. 2) Use an earlier kernel (3.5.0-14) ProblemType: Bug DistroRelease: Ubuntu 12.10 Package: linux-image-3.5.0-15-generic 3.5.0-15.22 ProcVersionSignature: Ubuntu 3.5.0-15.22-generic 3.5.4 Uname: Linux 3.5.0-15-generic x86_64 ApportVersion: 2.5.2-0ubuntu4 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: agy 2182 F.... pulseaudio Date: Mon Sep 24 16:45:57 2012 EcryptfsInUse: Yes HibernationDevice: RESUME=UUID=e58f26d0-910f-4f85-a240-cd9d404f38ca InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425) MachineType: SAMSUNG ELECTRONICS CO., LTD. 900X3C/900X4C/900X4D ProcEnviron: TERM=screen PATH=(custom, no user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 inteldrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.5.0-15-generic root=UUID=b281cccd-7e4d-4f82-9888-61890b3bafe4 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.5.0-15-generic N/A linux-backports-modules-3.5.0-15-generic N/A linux-firmware 1.93 SourcePackage: linux UpgradeStatus: Upgraded to quantal on 2012-09-14 (10 days ago) dmi.bios.date: 04/26/2012 dmi.bios.vendor: Phoenix Technologies Ltd. dmi.bios.version: P01AAC dmi.board.asset.tag: Base Board Asset Tag dmi.board.name: SAMSUNG_NP1234567890 dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD. dmi.board.version: FAB1 dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 9 dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD. dmi.chassis.version: 0.1 dmi.modalias: dmi:bvnPhoenixTechnologiesLtd.:bvrP01AAC:bd04/26/2012:svnSAMSUNGELECTRONICSCO.,LTD.:pn900X3C/900X4C/900X4D:pvr0.1:rvnSAMSUNGELECTRONICSCO.,LTD.:rnSAMSUNG_NP1234567890:rvrFAB1:cvnSAMSUNGELECTRONICSCO.,LTD.:ct9:cvr0.1: dmi.product.name: 900X3C/900X4C/900X4D dmi.product.version: 0.1 dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD. ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug quantal running-unity -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1055771 Title: Samsung 900X4C laptop boots with display backlight off To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1055771/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs