Exactly. Plus: Switching back and forth several times results in the X
server hanging (or rather lagging) for some minutes…

On Sun, Jul 3, 2011 at 13:28, Tom Gelinas <email address hidden> wrote:
> I have linked this bug to Ubuntu Hardware Certification.
> https://answers.launchpad.net/ubuntu-certification/+question/163597
>
> Hopefully they will treat this bug with respect. Switching between text
> mode VT and a Nvidia-proprietary powered X server is not stable!
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/562005
>
> Title:
>  Backlight controls of laptops with NVIDIA NVS and Quadro FX 880M GPUs
>  no longer function while using proprietary drivers
>
> Status in “nvidia-graphics-drivers” package in Ubuntu:
>  Confirmed
>
> Bug description:
>  The brightness controls of laptops with NVIDIA NVS 3100M or Quadro FX
>  880M GPUs work  while running Nouveau or when using a text mode VT,
>  but not while running X and using proprietary NVIDIA drivers.  It is
>  possible to force the NVIDIA driver to control the backlight by adding
>  [Option "RegistryDwords" "EnableBrightnessControl=1"] to the "Devices"
>  section of xorg.conf . While this allows the backlight to be
>  controlled, the increments are inconsistent and often result in a
>  buzzing noise from the LED backlight on Lenovo ThinkPad T510s and
>  W510s. Since this did not occur while running nouveau or when
>  switching in text VT, something is wrong.
>
>  This bad backlight behaviour has been confirmed on ThinkPad models T510 and W510 with NVIDIA NVS 3100m and Quadro FX 880M chipsets, respectively, via http://www.thinkwiki.org/wiki/Category:T510
>  Because this issue is related to NVIDIA's proprietary video driver, this issue can only be solved by them. An NVIDIA developer has said he will investigate the issues, which are  discussed on the nvnews.net forums at http://www.nvnews.net/vbulletin/showthread.php?t=145105 and http://www.nvnews.net/vbulletin/showthread.php?t=150069 . For future reference, the latest NVIDIA drivers can be found in the Ubuntu X-Swat X updates PPA: https://launchpad.net/~ubuntu-x-swat/+archive/x-updates
>
>
>  ProblemType: Bug
>  DistroRelease: Ubuntu 10.04
>  Package: nvidia-current 195.36.15-0ubuntu2
>  ProcVersionSignature: Ubuntu 2.6.32-19.28-generic 2.6.32.10+drm33.1
>  Uname: Linux 2.6.32-19-generic x86_64
>  NonfreeKernelModules: nvidia
>  Architecture: amd64
>  Date: Mon Apr 12 23:48:02 2010
>  DkmsStatus:
>   nvidia-current, 195.36.15, 2.6.32-19-generic, x86_64: installed
>  EcryptfsInUse: Yes
>  GdmLog1:
>
>  MachineType: LENOVO 4313CTO
>  ProcCmdLine: BOOT_IMAGE=/bhostnamet/vmlinuz-2.6.32-19-generic rhostnamet=UUID=0b95b314-337f-49aa-86f9-6423e76e9f20 ro
>  ProcEnviron:
>   LANG=en_CA.utf8
>   SHELL=/bin/bash
>  SourcePackage: nvidia-graphics-drivers
>  XorgLogOld:
>
>  dmi.bios.date: 02/22/2010
>  dmi.bios.vendor: LENOVO
>  dmi.bios.version: 6MET49WW (1 tp-smapi, 0.40, 2.6.32-19-generic, x86_64: installed
>   vboxnetadp, 3.1.6, 2.6.32-19-generic, x86_64: installed
>   vboxnetflt, 3.1.6, 2.6.32-19-generic, x86_64: installed
>   vboxdrv, 3.1.6, 2.6.32-19-generic, x86_64: installed.12 )
>  dmi.board.name: 4313CTO
>  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:bvr6MET49WW(1.12):bd02/22/2010:svnLENOVO:pn4313CTO:pvrThinkPadT510:rvnLENOVO:rn4313CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
>  dmi.product.name: 4313CTO
>  dmi.product.version: ThinkPad T510
>  dmi.sys.vendor: LENOVO
>  system:
>   distro:             Ubuntu
>   codename:           lucid
>   architecture:       x86_64
>   kernel:             2.6.32-19-generic
>
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>