Re:No backlight control on PowerBook G4

From: Benjamin Herrenschmidt
Date: Sun Nov 02 2003 - 19:49:52 EST

On Mon, 2003-11-03 at 06:23, Dustin Lang wrote:
> Hi,
> I just bought a new PowerBook G4 and installed Linux on it. Now the
> tweaking begins! One of the first orders of business is getting power
> management working, and I'm a bit stuck.

You can't expect a machine just released a couple of weeks ago by
Apple to be fully supported by linux, do you ? :)

> I'm running kernel version 2.4.22 with Ben Herrenschmidt's 2.4.23-pre5
> patches.
> On startup, arch/ppc/platform/pmac_backlight.c doesn't recognize the
> backlight controller. It checks compatibility with a couple of specific
> machines, and then checks compatibility with the backlight controller.
> This appears to be the same check that is performed in the Darwin/xnu
> kernel (at least the version that I found...).

If it's a new Mobility 9600 machine, then I expect my 2.6 tree
(bk:// or rsync from
to work, though the actual backlight "scale" may not be fully correct

> Any (non-null) pointers would be appreciated!

Unfortunately, there's isn't much HW documentation available for these
babies, other than reading Apple darwin source, Open Firmware forth
code, etc...

Regarding overall power management (that is machine sleep), it is not
supported on these machines yet. The blocking factor is the new ATI chip,
which need to be rebooted from scratch. ATI told me they might be able to
send me tables to do that though, so there is hope.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at