unobe@cpan.org once said:
> I reviewed the data sheet and the scripts should
> work, but does not.

The above scripts can work for some Intel cards
but probably not for all of them.

I wrote a program fifteen years ago to adjust the
brightness on an Intel MacBook from Linux. There
was a bit of experimentation involved to determine
register values that wouldn't cause problems. I've
attached it below.

Notice how I had to use a mask of 0xfffe instead
of 0xffff to keep the least significant bit zero
and how I had to be strict about maintaining the
maximum backlight level field when reading and
writing the register. I remember working through a
lot of blank and flickering screens before
arriving at something that worked.

I'm not near a machine with an Intel card at the
moment so I can't give you something that works on
Plan 9 but reading this old code may give you some
hints.

Cheers,
  Anthony

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