kernel-packages team mailing list archive

[Gaele Strootman <gaele@xxxxxxxxxxxx>]

Finally I found the courage to try commit bisecting the kernel. This is
the result:

4eebd5a4e72697aac25a8a57d3f888a9d5f80370 is the first bad commit
commit 4eebd5a4e72697aac25a8a57d3f888a9d5f80370
Author: Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx>
Date:   Wed Mar 11 22:34:45 2015 +0100

    apple-gmux: lock iGP IO to protect from vgaarb changes
    
    As GMUX depends on IO for iGP to be enabled and active, lock the IO at
    vgaarb level. This should prevent GPU driver for dGPU to disable IO for
    iGP while it tries to own legacy VGA IO.
    
    This fixes usage of backlight control combined with closed nvidia
    driver on some Apple dual-GPU (intel/nvidia) systems.
    
    On those systems loading nvidia driver disables intel IO decoding,
    disabling the gmux backlight controls as a side effect.
    Prior to commits moving boot_vga from (optional) efifb to less optional
    vgaarb this mis-behavior could be avoided by using right kernel config
    (efifb enabled but vgaarb disabled).
    
    This patch explicitly does not try to trigger vgaarb changes in order
    to avoid confusing already running graphics drivers. If IO has been
    mis-configured by vgaarb gmux will thus fail to probe.
    It is expected to load/probe gmux prior to graphics drivers.
    
    Fixes: ce027dac592c0ada241ce0f95ae65856828ac450 # nvidia interaction
    Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=86121
    Reported-by: Petri Hodju <petrihodju@xxxxxxxxx>
    Tested-by: Petri Hodju <petrihodju@xxxxxxxxx>
    Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
    Cc: Matthew Garrett <matthew.garrett@xxxxxxxxxx>
    Signed-off-by: Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx>
    Signed-off-by: Darren Hart <dvhart@xxxxxxxxxxxxxxx>

:040000 040000 b9fa60f95e23f0d9916f92df51b95e4b73c80ecf
d842064bce0c54557a3b1dd9dcd357f0e204dde1 M      drivers


** Bug watch added: Linux Kernel Bug Tracker #86121
   http://bugzilla.kernel.org/show_bug.cgi?id=86121

** Attachment added: "log.txt"
   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1512691/+attachment/4567749/+files/log.txt

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You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1512691

Title:
  [MacBookPro11,3] Backlight control does not work, but there are
  entries in /sys/class/backlight

Status in linux package in Ubuntu:
  Triaged

Bug description:
  Backlight control stopped working after upgrade from Vivid to Wily.

  /sys/class/backlight/gmux_backlight$ grep . *
  actual_brightness:16777215
  bl_power:0
  brightness:400
  grep: device: Is a directory
  max_brightness:-1
  grep: power: Is a directory
  grep: subsystem: Is a directory
  type:platform

  ProblemType: Bug
  DistroRelease: Ubuntu 15.10
  Package: linux-image-4.2.0-16-generic 4.2.0-16.19
  ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
  Uname: Linux 4.2.0-16-generic x86_64
  NonfreeKernelModules: wl
  ApportVersion: 2.19.1-0ubuntu4
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC1:  gaele      2525 F.... pulseaudio
   /dev/snd/controlC0:  gaele      2525 F.... pulseaudio
  CurrentDesktop: Unity
  Date: Tue Nov  3 13:44:25 2015
  EcryptfsInUse: Yes
  HibernationDevice: RESUME=UUID=716bc023-ef4e-436e-8e5b-5a1f548faef8
  InstallationDate: Installed on 2015-04-26 (190 days ago)
  InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
  MachineType: Apple Inc. MacBookPro11,3
  ProcFB: 0 nouveaufb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-16-generic.efi.signed root=UUID=38c8fe6d-3763-4619-a710-f65494173fe4 ro quiet splash libata.force=noncq vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-4.2.0-16-generic N/A
   linux-backports-modules-4.2.0-16-generic  N/A
   linux-firmware                            1.149
  SourcePackage: linux
  UpgradeStatus: Upgraded to wily on 2015-10-22 (11 days ago)
  dmi.bios.date: 06/05/2015
  dmi.bios.vendor: Apple Inc.
  dmi.bios.version: MBP112.88Z.0138.B15.1506050548
  dmi.board.asset.tag: Base Board Asset Tag#
  dmi.board.name: Mac-2BD1B31983FE1663
  dmi.board.vendor: Apple Inc.
  dmi.board.version: MacBookPro11,3
  dmi.chassis.type: 10
  dmi.chassis.vendor: Apple Inc.
  dmi.chassis.version: Mac-2BD1B31983FE1663
  dmi.modalias: dmi:bvnAppleInc.:bvrMBP112.88Z.0138.B15.1506050548:bd06/05/2015:svnAppleInc.:pnMacBookPro11,3:pvr1.0:rvnAppleInc.:rnMac-2BD1B31983FE1663:rvrMacBookPro11,3:cvnAppleInc.:ct10:cvrMac-2BD1B31983FE1663:
  dmi.product.name: MacBookPro11,3
  dmi.product.version: 1.0
  dmi.sys.vendor: Apple Inc.

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