Messages in this thread | | | From | "Rafael J. Wysocki" <> | Subject | Re: Reworking suspend-resume sequence (was: Re: PCI PM: Restore standard config registers of all devices early) | Date | Tue, 3 Feb 2009 23:44:21 +0100 |
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On Tuesday 03 February 2009, Benjamin Herrenschmidt wrote: > On Tue, 2009-02-03 at 22:53 +0100, Rafael J. Wysocki wrote: > > > That would change the ordering of ACPI method calls, which also is important > > and prone to breaking, as I wrote in the original message. > > Ok, I'm not -that- familiar with ACPI, but I don't see where this > ordering change you seem to fear is ... Ie, what gets re-ordered vs. > what ?
(Newer) ACPI says that devices should be put into low power states (presumably with the help of appropriate ACPI AML routines) before the _PTS method is called. In turn, we're supposed to disable nonboot CPUs after calling _PTS. There is analogous requirement for the _WAK method during resume.
Currently, the suspend code ordering follows these rules, but if we move the putting of devices into low power states into the suspend_late part, they will have to be done after _PTS and that is likely to break things (we've already had this problem once and I have really bad memories related to it).
Thanks, Rafael
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