The attached patch does two things:

1) Take PCI devices to D0 state before enabling them.  We both think
this is the right thing to do, but there is always the crazy chance this
change will break something.  So, think twice before applying, but IMHO
apply :)

2) Adds pci_disable_device.  Right now is just disables busmastering. 
When suspending devices, the last task that should occur is to disable
busmastering, before ceding control to ACPI.  Also its a good idea in
general to disable busmastering when its not in use; it's friendlier to
the bus.  When unloading drivers too, we should be more "green" about
disabling devices.

I wonder if we should disable IO and MEM decoding too, and I also like
to ack PCI_STATUS.  I didn't add those things because I'm not yet sure
we want to do that unconditionally.  Comments welcome.

-- 
Jeff Garzik       | "Give a man a fish, and he eats for a day. Teach a
Building 1024     |  man to fish, and a US Navy submarine will make sure
MandrakeSoft      |  he's never hungry again." -- Chris Neufeld