Touchpad loses sync with ACPI on.

[Matthew Marshall <matthew@matthewmarshall.org>]

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I am having a problem with the touchpad and pointer stick on my HP compaq 
nc6000 laptop.  It only happens when using ACPI.

Both pointing devices work for a while, but eventually start to 'stick'.  The 
cursor won't move for about a second, and then it jerks all over the screen, 
clicking.

This problem gradually increases in frequency, until eventually neither device
works at all.  Even cat'ing the respective /dev/input/event* device doesn't 
return anything, and I have to shut down or suspend the computer for 
about 15 minutes before it will work again.  (simply rebooting doesn't fix 
it.)  (Actually, it sometimes works if I press down REALLY hard... perhaps 
that's due to some sensitivity threshold being automatically adjusted?)

Everything works perfectly if I boot with acpi=off.  

(I also left Windows open all day once, and it didn't happen there either.)

I'm using kubuntu, and have tested it with kernel 2.6.20, 2.6.22.1, and 
2.6.23-rc1.

When the problem happens, I get lines like this from dmesg:

psmouse.c: TouchPad at isa0060/serio4/input0 lost sync at byte 1

or sometimes like this:

psmouse.c: TouchPad at isa0060/serio4/input0 lost synchronization, throwing 4 
bytes away.


From Google I have found a few other similar reports.  For one person this 
seems to happen under load.  For me, it sometimes seems to happen right when 
I start to compile or something, but it will also happen when I boot up the 
computer and don't even touch it.  (literally: I'll come back in a half an 
hour and the TP doesn't work.)

Someone else seemed to have the problem from reading ACPI states.  I have not 
been able to find any correlation in this respect.  I booted up without the 
battery panel applet and without starting acpid, and it still started 
hiccuping after 5 minutes.

There seems to be no correlation between how much I use it and how long it 
lasts.  Sometimes I can be using it constantly and it lasts an hour.  
Sometimes I barely touch it and it lasts only 10 minutes.

I'm attaching the output of dmesg, lshw, lsmod and lspci.

So, what more can I do?  Is there any more information I can provide?  Are 
there any patches I can try?  I'm willing to help out any way I can.

Thanks for reading,
Matthew Marshall

P.S. I'm not subscribed, so please CC any replies.

P.P.S. Sometimes it seems to be able to read my mind... Just when I think "wow 
it's lasting a long time!" it will freeze up within two seconds.  I 
understand that this might be hard for others to reproduce.

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