On Wednesday, 26 of December 2007, Linus Torvalds wrote:On Tue, 25 Dec 2007, Rafael J. Wysocki wrote:the ACPI specification between versions 1.0x and 2.0. Namely, while ACPIThat's insane. Are you really saying that ACPI wants totally different orderings for different versions of the spec?
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.
Yes, I am.
And does Windows really do that?
I don't know.
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().
Yes, that's what I'm going to do, but I need to untangle some ACPI code for
this purpose.
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.
Well, section 9.1.6 of ACPI 2.0 specifies the suspend ordering directly and
says exactly that _PTS is to be executed after putting devices into respective
D states.