Random hang when waking from sleep on ibook G4 + 2.6.14.3 kernel

[Benjamin Cama <benoar@free.fr>]

Hi,

First, i must admit i'm using ubuntu, not debian. Hope this won't
interfere with my problem, but i think it's kernel-related, and i know
that most of the ppc kernel stuff takes place here. I'm also new to this
list.

I regularly use the sleep feature of my iBook, and it works quite well
with a recent kernel, thanks to BenH patches. I used to have a
ubuntu-built 2.6.12, but it oopsed when waking from sleep while an USB
peripheral was plugged in (in my case, an USB mouse). I had to think to
unplug it each time i put my ibook to sleep, which i didn't remember all
the time... I found that this kernel had this problem, but that it was
resolved in more recent ones.
So i built a vanilla 2.6.14.3 kernel, and it worked well even when my
mouse was plugged-in and that i put my ibook to sleep. But one day, it
couldn't wake up, hanging on this screen :
http://benoar.free.fr/ibook_hangs.jpg
I tried to find the cause, but i couldn't reproduce this bug. I think it
is still due to some USB-related problem (you can see on the top of the
screen a previous wake-from-sleep that succeeded). It worked well for
another period, but this bug reappeared after a while.

It doesn't appear very often, and i can't reproduce this exactly, hence
the "random" of the subject of this mail. I didn't try a more recent
kernel (2.6.15 ?) but i could check, if someone thinks it comes from
this particular version.

Here's some detail :
benoar@benoar:~% uname -a
Linux benoar 2.6.14.3-benoar1 #1 PREEMPT Sun Dec 11 23:09:28 CET 2005
ppc GNU/Linux

Well... i just remember i activated preempt... may this be the problem ?
i think i already saw strange bug coming up when this option is
activated, in some post on this list.
The think is, if i check without preempt, how to check it won't happen
again...? Sleep/wake a lot of times ?

I'll be glad if someone could give me some advice.

Thanks in advance.

Benjamin Cama