[ltp] Re: news about Thinkpad brightness keys situation

[Jesse Barnes]

On Wednesday, April 30, 2008 1:52 am Yves-Alexis Perez wrote:
> Hi,
>
> I wanted to ask if there was any progress on the understanding of the
> situation?
>
> I have a Thinkpad T61 (8897 with intel G965), running Linux 2.6.25
> (vanilla+thinkpad-acpi 0.19-20080321, but I can test with debian 2.6.25)
> and xserver-xorg-video-intel 2.3.0-1 (experimental).
>
> Brightness keys sure don't work out of the box (nor in console nor in
> Xorg).
>
> acpid, powersaved and hald are running. I can stop them for testing if
> needed.
>
> The driver by default uses the BACKLIGHT_CONTROL "kernel".
>
> xbacklight works fine.
>
> I have a /sys/class/backlight/acpi_video0 and 1. acpi_video0 does nothing,
> but using acpi_video1 and echo'ing 0-15 to brightness works. But in that
> case, xbacklight is lost.
>
> xbacklight =100
> # brightness is at full level
> cat /sys/class/backlight/acpi_video1/actual_brightness
> 15 # acpi_video1 agree
> echo 0 > /sys/class/backlight/acpi_video1/brightness
> # brightness is at minimum level (but is not off, while it has worked at
> one # time)
> cat /sys/class/backlight/acpi_video1/actual_brightness
> 0 # acpi_video1 agree
> xbacklight
> 100 # xbacklight disagree.

This is an X server & driver problem.  I fixed it recently, so if you build 
the Intel X driver against new server bits (or just wait until 1.5), 
xbacklight should fetch the current value.

> That's even without trying brightness keys.
>
> Pressing brightness keys generates here acpi events video LCD0 87/86 (with
> some delay, but I guess this one is a kernel problem). Nobody seems to
> catch it, nor hal, nor powersaved, nor X driver.

I think in some kernel versions it'll send a keyboard event that you can make 
a desktop applet catch?

Jesse