On my workplace Thinkpad W530 (Quadro K1000M in discrete-only mode),
"EnableBrightnessControl=1" does in fact expose a working "Backlight" property
via xrandr.
Unfortunately, Gnome is looking for a property called "BACKLIGHT", and falls
back to /sys/class/backlight when it's not found.
See https://bugs.launchpad.net/ubuntu/+source/gnome-settings-daemon/+bug/947919
I've also managed to get the nvidiabl module to work, by setting the
'type' and 'max' parameters.
Gnome prefers backlights of type "platform" over type "raw". The non-
working thinkpad_screen is type "platform", and nvidia_backlight
defaults to "raw". Setting nvidia_backlight to "platform" fixes this.
My approach for figuring out the proper value of 'max':
1. Start with EnableBrightnessControl=1 set.
2. Load nvidiabl with some value (such as 0x1000) for 'max'. (If your
backlight turns entirely off, doing step 3 should turn it back on.)
modprobe nvidiabl max=<number>
3. Use xbacklight to change brightness to some lower value, then back to 100.
(If you just try to reapply 100, it won't work.)
xbacklight -set 50; xbacklight -set 100
4. Check what the reported 'actual_brightness' and 'brightness' values are.
grep . /sys/class/backlight/nvidia_backlight/*brightness
5. If brightness and actual_brightness both equal the max_brightness value,
you've found a 'max' that works.
If actual_brightness and brightness are below max_brightness, the guess for
'max' was too high.
If they're above max_brightness, the guess for 'max' was too low.
6. As a final sanity check, I verified that the brightness slider in
gnome works smoothly (that is, brightness changes occur over the whole
range).
7. Save that max in a module config file; I tend to put all my personal
options in /etc/modprobe.d/custom.conf
options nvidiabl type=platform max=<value you found>
Now I just need to remove "EnableBrightnessControl", since as it is now,
the nvidia driver reverts to the xbacklight value (100) whenever I click
a link in an e-mail.
--
You received this bug notification because you are a member of Desktop
Packages, which is subscribed to nvidia-graphics-drivers in Ubuntu.
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 Ubuntu Certification Programme:
Invalid
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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