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Re: How to control LCD backlight via program?

On Wed, Sep 24, 2003 at 07:36:33PM +0100, Carlos Sousa wrote:
> On Wed, 24 Sep 2003 14:55:06 +0800 Yun-Ta Tsai wrote:
> > Greeting,
> > 	I plan to write a script to control my lcd backlight while entering power 
> > saving mode.(Make it darker and after plugging in the AC power, it will 
> > become brighter.) Is that possible to control the degree of the light of LCD? 
> > I know someone wrote a program for Sony Vaio, is that possible do the same 
> > stuff on ASUS laptop?
> On my Asus L3C, running kernel 2.4.21 with ACPI patches, there's a file
> somewhere under /proc/acpi/ that you can cat a value to (between 0 and 15,
> I think), that will enable you to control the LCD backlight intensity.

/proc/acpi/asus/brn here, and .../asus/lcd  for backlight on/off status.

> I understand kernel 2.4.22 already has the latest ACPI patches included,
> but I havent' tried it yet.

You need to enable an ASUS-specific option in the kernel configuration
to enable this. And insert the corresponding module if you don't
compile it in.

There's an ACPI patch available against 2.4.22 from
http://acpi.sourceforge.net/, though I don't know how much of a
difference that makes. Updates to the ASUS ACPI driver can also be
found at http://sourceforge.net/projects/acpi4asus.


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