nvidia-bl-dkms 0.16.10 Blank screen on brightness change

My kernel is 2.6.32-23-generic.

(1) I have no information regarding your machine/graphics adapter right now. Thus, the maximum value the driver employs might be wrong. You can try the max_level parameter to tweak this. After you found a reasonable setting, please report back and I'll fix the driver. The remaining points for explanation.

(2) The max_level parameter is used to compute a mask to only overwrite the necessary least significant bits of an (undocumented) register. Thus, it should preferably be a power of 2 minus 1, e.g., Ox3ff (hexadecimal). If you use other values, the mask will be the set of least significant bits required to represent this value. But you cannot set higher values than specified, which is mainly useful on Sony machines.

(3) Higher values shouldn't destroy your machine. But please note that there's no quarantee. There's isn't even an official documentation available. However, I'd highly appreciate a value as exact as possible.

(4) You can try to figure it out like this: Set max_value to some large value, e.g., 0xffffff (2^24-1) and increase brightness until you observe no change in visible brightness anymore. This should be more or less around a power of 2 depending on the method you choose. Most precisely is:
$ echo <value> | sudo tee /sys/class/backlight/nvidia_backlight/brightness

(5) Please also disable any hacks in your xorg.conf regarding display backlight.

ciao,
Mario

I removed the hacks and set the maximum brightness to 16777215.
But still as soon as I change the brighness (up or down, via command line or Gnome) the screens goes dark.
If it helps, the screens goes dark in 2-3 steps not right away (but pretty fast).

Hi Mario,
I found the maximum value you are looking for:
0x1ff00
This is the minimum value that produces maximum brightness on my Geforce 310M (Vaio VPCCW21fx).
I was doing something wrong before.
Let me know if you need anything else.

... and is there a way to set a minimum value so the screen doesn't go dark?
0x01000 is a reasonable medium. Very dark but slightly readable.
0x00500 makes the screen almost completely dark.

Thanks. According to other machines the maximum could also be 0x1ffff. Correct? Nevertheless, to update the driver, I need the output of:
$ cat /sys/class/dmi/id/sys_vendor
$ cat /sys/class/dmi/id/product_name

Regarding your question: No. The driver is supposed to allow to turn off backlight completely. But how many steps do you have? In theory, the range should be 0-0x1ffff and userland tools are supposed to scale to a human-friendly range.

ciao,
Mario

Yes. the max could be 0x1ffff.
Here's the info you asked for:

$ cat /sys/class/dmi/id/sys_vendor
Sony Corporation
$ cat /sys/class/dmi/id/product_name
VPCCW21FX

P.S. I've pretty much got things working: I switched back to nvidia_bl-0.52 and used mix = 4096, max= 131071. The steps act weird and (according to gnome) it seems to jump the steps, but at least I can turn the screen a bit darker.