How is monitor brightness is controlled ?

[Ievgen Krapyva]

Thank you, Stewart, 

I've already got some knowledge and looked throught the variables, there is 
nothing similar in there. 

devel-pc# sysctl -a | grep lcd
devel-pc# sysctl -a | grep brightness

I've also tried loading acpi_video.ko, that also does not work. 
In fact none of the Fn+ combintations work on my laptop, except  of
Fn+F2 (turns on/off Wireless devices). 
I feel it's not under control of FreeBSD rather BIOS is doing it (correct me 
if I'm wrong). Pressing this combination just turns off Wi-Fi on a hardware 
level, in FreeBSD I can see the effect by examining the contents of dmesg:

wlan0: link state changed to DOWN

I assume I should move in the direction of ACPI, right ?

Best regards, 
Ievgen

On Tuesday 15 May 2012 12:37:01 you wrote:
> On 05/13/12 17:55, Yevgen Krapiva wrote:
> > Hi everyone.
> > 
> > Could somebody tell me what thing in FreeBSD is managing the monitor
> > brightess ?
> 
> Given that the function keys don't work, check if you have any relevant
> sysctl options to play with. Most likely to find them under hw.acpi, but
> try grepping "sysctl -a" output for bright or lcd to see if anything
> comes up.
> 
> > I've got Dell Inspiron laptop, FreeBSD 9.0 RELEASE and KDE4.
> > Pressing the functional combintation of Fn+F4/F5 does not have any
> > effect. In order to understand what's wrong I need to know in what
> > direction I should move.
> 
> Getting the fn keys working requires some ACPI voodoo I'm not familiar
> with, so I'll have to defer to someone else to advise on that. The info
> at [1] might be a good starting point. The fn keys on my Toshiba R600
> laptop started working only after I loaded the acpi_toshiba.ko kernel
> module. I note there's no similar module for Dell's so getting them
> working will probably require some fiddling.
> 
> Cheers,
> Lawrence
> 
> [1]
> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/acpi-debug.html