kernel-packages team mailing list archive

[Mark Pettengell <1485246@xxxxxxxxxxxxxxxxxx>]

Right, so I have re-tested having installed the 4.2.0-040200rc7-generic
kernel. The behaviour seems to be identical to the stock Ubuntu 15.04
kernel.

A few things I have noticed having carried out several reboots and
suspends in the process of testing this. These apply to both the stock
kernel and the 4.2 kernel:

With kernel parameter acpi_backlight=vendor
1. On first boot the brightness of the screen is about 60% brightness and attempts to change the brightness setting via the hotkeys causes the brightness level notification to flicker and the brightness level cannot be altered
2. After a suspend the brightness returns to about 100% and using the hotkeys may then work (i.e brightness controls have been properly restored). This occurs on about 2 in 3 wakes from suspend, the other 1 in 3 the brighness is 100% but control over brightness still non-functional

with no acpi_backlight kernel param
1. The initial boot brightness is approximately the same as above. Attempts to change this successfully move the brightness level in the indicator, but have no impact on the actual screen brighness.
2. wake from suspend results in the 100% brightness as above, but no control of screen brightness still

Not sure if any of that actually helps any...

Let me know if I can extract any further useful information to help with
debugging.

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

** Tags added: kernel-bug-exists-upstream

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https://bugs.launchpad.net/bugs/1485246

Title:
  Backlight issue - Samsung Chronos 7 (model - NP770Z5E)

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  Control of screen backlight is broken with a default clean install of
  Ubuntu 15.04 on my Samsung Series 7 Laptop (NP770Z5E). Setting kernel
  parameter 'acpi_backlight=vendor' fixes the issue after two reboots.
  Debugging information attached as per -
  https://wiki.ubuntu.com/Kernel/Debugging/Backlight

  ProblemType: Bug
  DistroRelease: Ubuntu 15.04
  Package: linux-image-3.19.0-25-generic 3.19.0-25.26
  ProcVersionSignature: Ubuntu 3.19.0-25.26-generic 3.19.8-ckt2
  Uname: Linux 3.19.0-25-generic x86_64
  ApportVersion: 2.17.2-0ubuntu1.2
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  mark       1699 F.... pulseaudio
  Date: Sat Aug 15 21:36:20 2015
  HibernationDevice: RESUME=UUID=c4899b44-3e19-4e62-921d-cf0a1cef97ec
  InstallationDate: Installed on 2015-08-12 (3 days ago)
  InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
  MachineType: SAMSUNG ELECTRONICS CO., LTD. 770Z5E/780Z5E
  ProcFB:
   0 inteldrmfb
   1 radeondrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-25-generic root=UUID=5a02817b-1f9b-4abc-93a3-b10d5d9278ed ro quiet splash acpi_backlight=vendor vt.handoff=7
  PulseList:
   Error: command ['pacmd', 'list'] failed with exit code 1: Home directory not accessible: Permission denied
   No PulseAudio daemon running, or not running as session daemon.
  RelatedPackageVersions:
   linux-restricted-modules-3.19.0-25-generic N/A
   linux-backports-modules-3.19.0-25-generic  N/A
   linux-firmware                             1.143.3
  SourcePackage: linux
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 09/05/2013
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: P05ABU.142.130905.SK
  dmi.board.asset.tag: No Asset Tag
  dmi.board.name: NP770Z5E-S02UK
  dmi.board.vendor: SAMSUNG ELECTRONICS CO., LTD.
  dmi.board.version: SEC_SW_REVISION_1234567890ABCD
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 9
  dmi.chassis.vendor: SAMSUNG ELECTRONICS CO., LTD.
  dmi.chassis.version: N/A
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrP05ABU.142.130905.SK:bd09/05/2013:svnSAMSUNGELECTRONICSCO.,LTD.:pn770Z5E/780Z5E:pvrP05ABU:rvnSAMSUNGELECTRONICSCO.,LTD.:rnNP770Z5E-S02UK:rvrSEC_SW_REVISION_1234567890ABCD:cvnSAMSUNGELECTRONICSCO.,LTD.:ct9:cvrN/A:
  dmi.product.name: 770Z5E/780Z5E
  dmi.product.version: P05ABU
  dmi.sys.vendor: SAMSUNG ELECTRONICS CO., LTD.

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