On Tue, 25 Dec 2007, Rafael J. Wysocki wrote:
>
> the ACPI specification between versions 1.0x and 2.0. Namely, while ACPI
> 2.0 and later wants us to put devices into low power states before calling
> _PTS, ACPI 1.0x wants us to do that after calling _PTS. Since we're following
> the 2.0 and later specifications right now, we're not doing the right thing for
> the (strictly) ACPI 1.0x-compliant systems.
>
> We ought to be able to fix things on the high level, by calling _PTS earlier on
> systems that claim to be ACPI 1.0x-compliant. That will require us to modify
> the generic susped code quite a bit and will need to be tested for some time.
That's insane. Are you really saying that ACPI wants totally different
orderings for different versions of the spec? And does Windows really do
that?
Please don't make lots of modifications to the generic suspend code. The
only thing that is worth doing is to just have a firmware callback before
the "device_suspend()" thing (and then on a ACPI-1.0 system, call _PTS
*there*), and on an ACPI-2.0 system, call _PTS *after* device_suspend().
Still, the fact is, some (most, I think) drivers *should* put themselves
into D3 only in "late_suspend()", so if ACPI-2.0 really expects _PTS to be
called after that, we're just screwed. That's when the system is really
down, interrupts disabled etc, we don't want to call anything but the
final ACPI "turn us off" stuff there!
Linus
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