[Mactel-linux-devel] No sysfs Backlight Interface on an iMac 10, 1 (ATi Radeon HD 4670)

[Bastien D. <es...@gm...>]

Hi,

I already settled the problem on another mailing list :
http://lists.alioth.debian.org/pipermail/pommed-devel/2011-May/000077.html
I got interesting insights from James Cameron but I got stuck when
trying to obtain the right address from Mac OS X.

I was inspecting the following program:
http://mattdanger.net/2008/12/adjust-mac-os-x-display-brightness-from-the-terminal/

But unfortunately I can't access the source of the function which seems
to do the dirty work because the file iomig64.c is missing in
http://www.opensource.apple.com/

Right now I'm thinking on trying a brute force approach.
Since the backlight value seems to be kept from Mac OS X to Linux, how
about: 
-- Setting the backlight value to minimum on Mac OS X, rebooting
into Linux and dumping the content of the interesting parts of memory
into file A, reboot into Mac OS X, set the brightness to the maximum,
reboot into Linux, dump the memory into file B.
-- Extracting the address(es) where the value in file A is 0 and the value
in file B is 256.

Does it seem like a viable approach ?
I thought that x1600_backlight.c, which is included in pommed sources,
might be a good starting point ?

Cheers,
-- 
Bastien