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[Bug 1173984] Re: 8086:0166 [Lenovo ThinkPad T530] Backlight control via fn-keys is stuck in certain ranges


The issue does not occur anymore. It has been fixed, but not completely
satisfactory, by a workaround in the kernel to use an older backlight
control method than one comparable to Windows 8 which provides a more
finegraned control. All in all backlight control support is back to the
level of quantal in raring and saucy: functional.

I just tried to install the 2.57 update, but the updater told me that I
already have the latest version.

$ sudo dmidecode -s bios-version && sudo dmidecode -s bios-release-date
G4ET97WW (2.57 )

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  8086:0166 [Lenovo ThinkPad T530] Backlight control via fn-keys is
  stuck in certain ranges

Status in “linux” package in Ubuntu:

Bug description:
  I just upgraded my quantal installation on my Lenovo T530 to raring
  and found the backlight control via fn-keys not functioning properly
  as it did in quantal.

  The backlight is initially set to 100% and can only be reduced to 95%.
  Setting the value to lower levels, brightness can the be controlled
  via fn-keys between 95% and 80%, 80% and 20%. The last range is from
  20% to 0%. When booting raring with the quantal kernel, brightness can
  be controlled without issues.

  The system is setup with UEFI and only Intel graphics (no hybrid). Clean MBR installation of raring to an external drive shows the same issue.
  ApportVersion: 2.9.2-0ubuntu8
  Architecture: amd64
   /dev/snd/controlC0:  livewire   2491 F.... pulseaudio
   country DE:
   	(2400 - 2483 @ 40), (N/A, 20)
   	(5150 - 5250 @ 40), (N/A, 20), NO-OUTDOOR
   	(5250 - 5350 @ 40), (N/A, 20), NO-OUTDOOR, DFS
   	(5470 - 5725 @ 40), (N/A, 26), DFS
  DistroRelease: Ubuntu 13.04
  HibernationDevice: RESUME=UUID=75748ef4-e058-4ab6-be00-a6dd36ebcad0
  InstallationDate: Installed on 2012-10-20 (190 days ago)
  InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
  MachineType: LENOVO 2392CTO
  MarkForUpload: True
  Package: linux (not installed)
   PATH=(custom, no user)
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-19-generic root=UUID=54762617-6f49-4a10-9c05-e6f9af033bd3 ro quiet splash vt.handoff=7
  ProcVersionSignature: Ubuntu 3.8.0-19.29-generic 3.8.8
   linux-restricted-modules-3.8.0-19-generic N/A
   linux-backports-modules-3.8.0-19-generic  N/A
   linux-firmware                            1.106
  Tags:  raring
  Uname: Linux 3.8.0-19-generic x86_64
  UpgradeStatus: Upgraded to raring on 2013-04-28 (0 days ago)
  UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
  dmi.bios.date: 12/20/2012
  dmi.bios.vendor: LENOVO
  dmi.bios.version: G4ET90WW (2.50 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 2392CTO
  dmi.board.vendor: LENOVO
  dmi.board.version: Not Defined
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnLENOVO:bvrG4ET90WW(2.50):bd12/20/2012:svnLENOVO:pn2392CTO:pvrThinkPadT530:rvnLENOVO:rn2392CTO:rvrNotDefined:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 2392CTO
  dmi.product.version: ThinkPad T530
  dmi.sys.vendor: LENOVO

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