hybrid-graphics-linux team mailing list archive

[Michal Kottman <k0mpjut0r@xxxxxxxxx>]

On Wed, 2010-10-06 at 21:42 -0700, AbeOwitz wrote:
> Been trying to learn ACPI via the acpi_call kernel module. 

IMO (from a perspective of acpi_call maker) - not a good way to learn
ACPI :) For more detailed info, look at
http://www.acpica.org/documentation/

> I experimented with the DSDT.dsl output, and found two commands that
> brighten and darken the laptop LCD.  (Asus U43JC Ubuntu 10.10 RC
> 64bit)
> 
> echo "\_SB.PCI0.RP00.VGA.UPBL" > /proc/acpi/call
> echo "\_SB.PCI0.RP00.VGA.DWBL" > /proc/acpi/call
> 
> I've not found anything else useful.  (Well, something messed up my
> laptop enough to prevent it from turning back on. I had to remove the
> battery and power before it would power up again. :(   )

I am not sure if it is OK to test and call every single method in your
DSDT, because there can be some side effects. For example, if I call my
\_SB.PCI0.PEG1.GFX0._OFF several times, the settings for my GPU changes
in BIOS - so that the dedicated GPU is always turned off. When I want to
use it in Windows, I have to turn it back on in BIOS.

> Nor do I seem to be able to pass parameters.  According to the
> acpi_call source code, I should be able to pass integers or hex
> integers separated by spaces.  i.e.  echo "\_SB.PCI0.RP00.VGA.DWBL
> 0x00" > /proc/acpi/call  but this always fails.

You can get the last error back, by reading /proc/acpi/call, for
example: cat /proc/acpi/call