From: Ryan Lortie <desrt@desrt.ca>
Subject: ACPI on Macbook
Date: Tue, 06 Jun 2006 02:45:47 -0400
Message-ID: <1149576347.660.9.camel@moonpix.desrt.ca>
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Sender: linux-acpi-owner@vger.kernel.org
To: linux-acpi@vger.kernel.org
Cc: Matthew Garrett <mjg59@srcf.ucam.org>


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Hello.

I have been working on getting my new Macbook working with Ubuntu dapper
for suspend.

Initially, the machine would crash on wake up.  I created a fix to the
PCI drivers for that and now it doesn't crash (fix is now in the Ubuntu
kernel repository).

After this fix I noticed that ACPI was non-functional after reboot.
This is because the irq9 handler gets disabled with the "nobody cared"
message.

This happens because when the machine comes up, irq9 is high
(level-triggered) but the ACPI code doesn't think it has anything to do.
It therefore returns IRQ_NONE instead of IRQ_HANDLED and the kernel
starts ignoring irq9 (preventing ACPI from working).

I found that the cause of this problem is that when the laptop returns
from sleep the SCI_EN bit has been cleared.  Actually, the entire PM1
register has been cleared (from inspecting the ports with a userspace
app).  On the ICH7 you can directly set this bit by 'or'ing the contents
of the PM1 port (0x404) with the value 0x01.

Currently in my custom-patched kernel I have a quick outw(1, 0x404); as
soon as the system comes back from sleep (before re-enabling interrupts,
even).  This fixes the problem and no spurious irq9's are issued.

This works smashingly well for me but unfortunately it's a gigantic ugly
hack.  I've been talking to Matthew Garrett (mjg59) about this problem
and he suggested that it might be at least a tiny bit cleaner to put a
call to acpi_enable() there instead (set SCI_EN indirectly since the
ACPI spec says it might not be correct to set it directly).
Unfortunately, when I do this the machine locks on resume.

So I'm writing this list to ask a couple of things:

1) Why do y'all think SCI_EN is being cleared when the machine goes to
sleep and wakes up again?

2) What is the best way of dealing with this problem in a non-hackish
way?

I'm not on the list so please reply-to-all.

Cheers

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