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[Bug 921323] Re: Display backlight is turned off completely when AC adapter is plugged in while battery is critically low


I still experience this bug using Ubuntu 15.04 on the same machine as
before (ThinkPad T420s).

** Changed in: linux (Ubuntu)
       Status: Expired => Incomplete

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  Display backlight is turned off completely when AC adapter is plugged
  in while battery is critically low

Status in linux package in Ubuntu:

Bug description:
  If the battery is critically low (so that the Unity battery indicator has turned red already) and the AC adapter is plugged in, the display backlight is turned off completely. The screen appears to be completely black, looking at it closely however reveals that it is still on - without any backlight. Shutting and reopening the lid as well as shutting it down completely fixes the condition. This bug occurs reproducibly on a Thinkpad T420s.
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
  ApportVersion: 1.23-0ubuntu4
  Architecture: amd64
   **** List of CAPTURE Hardware Devices ****
   card 0: PCH [HDA Intel PCH], device 0: CONEXANT Analog [CONEXANT Analog]
     Subdevices: 1/1
     Subdevice #0: subdevice #0
   /dev/snd/controlC0:  florian    1998 F.... pulseaudio
  CRDA: Error: [Errno 2] No such file or directory
   Card hw:0 'PCH'/'HDA Intel PCH at 0xf1620000 irq 51'
     Mixer name	: 'Intel CougarPoint HDMI'
     Components	: 'HDA:14f1506e,17aa21d2,00100002 HDA:80862805,80860101,00100000'
     Controls      : 21
     Simple ctrls  : 9
   Card hw:29 'ThinkPadEC'/'ThinkPad Console Audio Control at EC reg 0x30, fw unknown'
     Mixer name	: 'ThinkPad EC (unknown)'
     Components	: ''
     Controls      : 1
     Simple ctrls  : 1
   Simple mixer control 'Console',0
     Capabilities: pswitch pswitch-joined penum
     Playback channels: Mono
     Mono: Playback [on]
  DistroRelease: Ubuntu 11.10
  HibernationDevice: RESUME=UUID=26874031-4fdb-442d-9bc6-f2f89a0a3113
  InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
  MachineType: LENOVO 4170CTO
  Package: linux (not installed)
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-16-generic root=UUID=83bc2d69-d3b1-42ec-a17f-0b323d98bad0 ro quiet splash i915.i915_enable_rc6=1 pcie_aspm=force vt.handoff=7
  ProcVersionSignature: Ubuntu 3.0.0-16.28-generic 3.0.17
   linux-restricted-modules-3.0.0-16-generic N/A
   linux-backports-modules-3.0.0-16-generic  N/A
   linux-firmware                            1.60
  StagingDrivers: mei
  Tags:  oneiric running-unity staging
  Uname: Linux 3.0.0-16-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm admin cdrom dialout lpadmin plugdev sambashare
  dmi.bios.date: 07/11/2011
  dmi.bios.vendor: LENOVO
  dmi.bios.version: 8CET46WW (1.26 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 4170CTO
  dmi.board.vendor: LENOVO
  dmi.board.version: Not Available
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 10
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: Not Available
  dmi.modalias: dmi:bvnLENOVO:bvr8CET46WW(1.26):bd07/11/2011:svnLENOVO:pn4170CTO:pvrThinkPadT420s:rvnLENOVO:rn4170CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
  dmi.product.name: 4170CTO
  dmi.product.version: ThinkPad T420s
  dmi.sys.vendor: LENOVO

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