Environment: ubuntu 12.10 x64, bios (have tried 2.06, 2.50). W530 2436CTO, 3720QM, K1000M.

The problem can be described below (May looks duplicate at first sight)

The back light of screen after installed Nvidia driver(Nvidia current from x-updates, or the different version from 304.32~311.32 from Nvidia download site) is always with the highest level. change the value of `/sys/class/backlight/acpi_video/brightness` have not any effect. Seems as if the brightness control is entirely not working.

I have tried to add `acpi=thinkpad`, `acpi=vendor`, `acpi=legacy` to linux kernel argument, but no lucky (that should be, because from the very begin I can see `thinkpad_acpi` mod loaded).

I also have tried to modify the `/usr/share/X11/xorg.conf.d` to include a conf file to include 

```
Option "RegistryDwords" "EnableBrightnessControl=1" (either manually, or via modify /usr/share/ubuntu-drivers-common/quirks/   

```

to allow the parameter to be included... A bit strange, in the materials provided by `nvidia-current`, these options were added to screen section. I have tried to put them both in device and screen section, but still no lucky)
Nothing changed.

In either cases, `cat /proc/driver/nvidia/parameter` shows empty string for `RegistryDwords`, but I can find logs in `/var/log/Xorg.0.log` include strings below: 

```
19.745] (==) NVIDIA(0): RGB weight 888
[    19.745] (==) NVIDIA(0): Default visual is TrueColor  
[    19.745] (==) NVIDIA(0): Using gamma correction (1.0, 1.0, 1.0)  
[    19.745] (**) NVIDIA(0): Option "NoLogo" "True"  
[    19.745] (**) NVIDIA(0): Option "RegistryDwords" "EnableBrightnessControl=1"  
[    19.745] (**) NVIDIA(0): Enabling 2D acceleration    
[    20.588] (II) NVIDIA(GPU-0): Display (Lenovo Group Limited (D  

```

Nothing says the option is illegal (as I have tried to use some unaccepted option name).

So I have to doubt, could there be any other things affect this?

I have seen threads mentioned something in gnome setting daemon may produce similar issue, but the solution in those threads didn't help.

Nvidiabl modules can help to dim the screen, but there are something wrong which caused the backlight too dimmer: the brightness value read in `/sys/class/backlight/nvidia-`backlight/brightness is very large (may be random, from over 3000+ to 10k+), while the `max_brightness` is only `127`. set any value below `127` cause the screen to be too dark to read, so this workaround not work for me too.

Because I have seen people works fine with W530 + Nvidia + Ubuntu X64, and I have tried to nvidia driver from the first beta version which support K1000m to the latest version, I am doubt what could cause this issue and how should I continue the analysis?