mactel-support team mailing list archive

[Mario Schwalbe <schwalbe@xxxxxxxxxxxxxxxxx>]

(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

-- 
nvidia-bl-dkms 0.16.10 Blank screen on brightness change
https://bugs.launchpad.net/bugs/599607
You received this bug notification because you are a member of Mactel
Support, which is the registrant for Mactel Support.

Status in Mactel Support: New

Bug description:
I have a Sony Vaio VPCCW21FX (Nvidia 310M) running Lucid.

After I installed nvidia-bl-dkms 0.16.10, the brightness buttons showed the brightness indicator but it didn't move.
Manually writing values to /sys/class/backlight/nvidia_backlight/brightness turn the backlight completely off (the backlight only turned back on after a suspend/resume).

Then I copied sony brightness scripts from here:

http://ubuntuforums.org/showthread.php?t=1420341

... after that, using the brightness buttons on the laptop turned the screen off as well.