Re:No backlight control on PowerBook G4

From: Dustin Lang
Date: Mon Nov 03 2003 - 03:52:55 EST

Hi Ben,

> 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 very impressed at how well things are supported. I had to buy a USB
wireless dongle, the Linksys WUSB12 (which works great), thanks to
Broadcom's proprietariness about the Airport Extreme, but other than that,
almost everything is automagic.

> 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
> yet.

Actually, it's got a GeForce FX Go 5200.

I just grabbed your 2.6 tree and see the same things happening.

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

Oh joy. I've heard great things about Forth :)

> 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.

Cool. I think backlight control, drive spindown, and CPU frequency
scaling should go a fairly long way on the battery life front. Speaking
of CPU scaling, do you know if it should work on this machine? I selected
it in the kernel config, but /sys/devices/system/cpu/cpu0 is empty.

Just for reference, /proc/cpuinfo is:

cpu : 7457, altivec supported
clock : 999MHz
revision : 1.1 (pvr 8002 0101)
bogomips : 761.85
machine : PowerBook6,2
motherboard : PowerBook6,2 MacRISC3 Power Macintosh
board revision : 00000002
detected as : 287 (Unknown Intrepid-based)
pmac flags : 00000008
L2 cache : 512K unified
memory : 256MB
pmac-generation : NewWorld

Oh, I just noticed something else in dmesg:
PMU driver 2 initialized for Core99, firmware: 0c


I grabbed the newest Darwin/xnu source I could find from Apple, and I can
no longer find where they do the backlight control - it used to be in
iokit/Drivers/platform/drvApplePMU . I'll have to look more closely

Again, many thanks for your work on this platform.

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