Re: 2.6.25-rc2 System no longer powers off after suspend-to-disk. Screen becomes green.

On Thursday, 21 of February 2008, Linus Torvalds wrote:

On Thu, 21 Feb 2008, Rafael J. Wysocki wrote:

In fact we have acpi_pci_choose_state() that tells the driver which power
state to put the device into in ->suspend(). If that is used, the device ends
up in the state expected by to BIOS for S4.

First off, nobody should *ever* use that directly anyway.

Yes, sorry.

Secondly, the one that people should use ("pci_choose_state()") doesn't
actually do what you claim it does. It does all kinds of wrong things, and
doesn't even take the target state into account at all. So look again.

Well, if platform_pci_choose_state() is defined, pci_choose_state() returns
its result and on ACPI systems that points to acpi_pci_choose_state(), so in
fact it does what I said (apart from the error path).

No. Again, if there are devices that wake us up from S4, but not from S5,
they need to be handled differently in the *enter S4* case (hibernation) and
in the *enter S5* case (powering off the system).

And again, what does this have to do with (the example I used) the
graphics hardware? Answer: nothing. The example I gave you we simply DO
THE WRONG THING FOR.

Same thing for things like USB devices - where pci_choose_state() doesn't
work to begin with. Why do we call "suspend()" on such a thing when we
don't want to suspend it? We shouldn't. We should call "freeze/unfreeze"
(which are no-ops) and then finally perhaps "poweroff", and that final
stage might want to spin things down or similar.

I'm already convinced, really. :-)

Thanks,
Rafael
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