[ltp] Brightness control on X60

[Nathaniel Smith]

On my X60 (brand new, 1709CTO, Intel video), I seem to have most
things working under Debian but... for some reason the lcd brightness
controls are broken.  (And here I thought my problem would be getting
suspend working...)

In particular, if I do Fn-Home/Fn-End to increase/decrease the
brightness then it works fine in the console, but if I do it in X,
then the backlight immediately turns off.  If I switch VTs back to the
console, then the light turns back on, but if I switch back to X
again, it turns off again.  (I.e., X is just dead, consistently and
permanently, even though other things works fine.)  If I restart X
(e.g., Ctrl-Alt-Backspace), that also brings things back, but rather
defeats the purpose of all that suspend magic...

I'm using the latest hal from Debian unstable (0.5.9), which
supposedly knows that the magic buttons are handled directly in
firmware (lshal says "laptop_panel.brightness_in_hardware = true"),
and if I shut down hal etc. then the buttons still kill X, so I don't
think it's misconfiguration there.

In fact, if I use /proc/acpi/ibm/brightness or
/sys/panel/backlight/*/brightness to adjust the backlight, it works
perfectly -- doesn't affect X at all.  So a workaround would be to
bind some other keys to control brightness in software, and just be
careful to never touch the Fn-control keys.  However, this both bugs
my sense of elegance, and also I'm uncomfortable with having "kill my
computer" buttons sitting right there, even if I also know not to
press them...

Anyone else encountered anything like this?  Any ideas?

-- Nathaniel

-- 
Electrons find their paths in subtle ways.