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[Bug 1535470] Re: Backlight brightness keys not working


I have a different Clevo model (P751DM-G) but with same issue: the
backlight Fn-keys doesn't work neither out of the box, nor with a kernel
4.6. Well, in fact, they work until I suspend/resume, and then they no
longer work. Looking at acpi_listen, I noticed that after first
suspend/resume cycle, some ACPI events where no longer triggered (like
the backlight Fn-keys, but also the lid close!).

I found a fix by loading a clevo-wmi driver. There are several clevo-wmi drivers on the internet (various attempts to write a driver for it...). For my laptop, I use:
* https://bitbucket.org/lynthium/clevo-xsm-wmi (it aims at supporting all Clevo models)

Since the clevo-xsm-wmi driver doesn't seem to handle your P65 model, you may need to try some other ones, like this one:
* https://github.com/gamaral/clevo-wmi
Maybe it could help for you too.

To be honest, I have no idea why it did fix my backlight fn-keys, as
those drivers are supposed to handle different features (keyboard
backlight, rfkill switch, hw monitoring). Nevertheless, if I unload the
module, then the issue happen again.

Note that this workaround fixes the Fn-keys: the backlight popup notification appears and I can increase/decrease value, however it has no effect on the screen. This is just ACPI event that has been fixed.
In order to really adjust LCD backlight, I have to play with nvidia-settings (with proprietary driver). Example, to set backlight brightness at 50%:

nvidia-settings -n -a BacklightBrightness=50

Some glue is still missing to link ACPI events with nvidia-settings.

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  Backlight brightness keys not working

Status in linux package in Ubuntu:

Bug description:
  Originally described in bug 1533221. This is a new bug to track this
  additional issue separately.

  The above bug has h/w info attached etc. This is a new skylake

  Backlight function keys are not working. I have tried various
  combinations of:

  acpi_osi=Linux acpi_backlight=native
  acpi_osi=Linux acpi_backlight=vendor
  acpi_osi=! acpi_backlight=vendor
  etc, etc

  with no luck.
  ApportVersion: 2.19.1-0ubuntu5
  Architecture: amd64
   /dev/snd/controlC0:  ian        2218 F.... pulseaudio
  CurrentDesktop: Unity
  DistroRelease: Ubuntu 15.10
  HibernationDevice: RESUME=UUID=df036c01-8f22-4d8f-ad55-6add4f99f5f4
   Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
   Bus 001 Device 004: ID 5986:066d Acer, Inc 
   Bus 001 Device 003: ID 8087:0a2b Intel Corp. 
   Bus 001 Device 002: ID 1c7a:0603 LighTuning Technology Inc. 
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
  MachineType: Notebook P65_P67RGRERA
  NonfreeKernelModules: nvidia_modeset nvidia
  Package: linux (not installed)
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-0-generic root=UUID=2077d068-d7ee-4407-89e1-7d2b884173de ro acpi_osi=Linux acpi_backlight=native drm.debug=14
  ProcVersionSignature: Ubuntu 4.4.0-0.12-generic 4.4.0
   linux-restricted-modules-4.4.0-0-generic N/A
   linux-backports-modules-4.4.0-0-generic  N/A
   linux-firmware                           1.155
  Tags:  wily
  UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
  Uname: Linux 4.4.0-0-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo
  _MarkForUpload: True
  dmi.bios.date: 11/20/2015
  dmi.bios.vendor: American Megatrends Inc.
  dmi.bios.version: 1.05.10
  dmi.board.asset.tag: Tag 12345
  dmi.board.name: P65_P67RGRERA
  dmi.board.vendor: Notebook
  dmi.board.version: Not Applicable
  dmi.chassis.asset.tag: No Asset Tag
  dmi.chassis.type: 10
  dmi.chassis.vendor: Notebook
  dmi.chassis.version: N/A
  dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1.05.10:bd11/20/2015:svnNotebook:pnP65_P67RGRERA:pvrNotApplicable:rvnNotebook:rnP65_P67RGRERA:rvrNotApplicable:cvnNotebook:ct10:cvrN/A:
  dmi.product.name: P65_P67RGRERA
  dmi.product.version: Not Applicable
  dmi.sys.vendor: Notebook

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