Re: fixing usb suspend/resuming

From: Alexander Gran
Date: Mon Jul 19 2004 - 02:29:00 EST

Hash: SHA1

Am Samstag, 17. Juli 2004 19:32 schrieb David Brownell:
>> I'm not clear on the intended relationship between PCI device state
> numbers and ACPI device states in Linux ... but it's clear from the
> specs (ACPI ch2, the mostly-generic bit) that ACPI "3" != PCI "3".

ermm, ok. It is even more complicated. Section 2 of the ACPI specs speaks of
Global Power states and device power states.
So we ge the follwing, with G= ACPI Global power state, S = (ACPI?) Sleep
State, D = ACPI Device power state,
G3 = Mechanical off = everything D3
G2=S5=soft off = everything D3
G1=S4 = Hibernation = everything D3
G1=S3/S2=Sleeping = parts in D2/D1/(D0?)
G0=S0=Working = evrything in D0

/proc/acpi/sleep talks about the S states, so when I want STR, which is S3 i
echo 3 > /proc/acpi/sleep.
The PCI state would also be 3 for most devices, I think. Pci state 1 or 2
cannot be expected to be supported.

> I'm suspecting that something is mistranslating between ACPI
> power state numbering and PCI power state numbering


> I'd _certainly_ expect that the numbers passed to PCI suspend
> and resume calls would match the PCI state numbers, not the
> ACPI numbers! But those numbers aren't documented in the
> Linux sources, so probably different people are making rather
> different assumptions. After all, "3 == 3" and "2 == 2".
> That's all different from the ACPI system power states, too.
> (Which is what I'd expect /proc/acpi/sleep to affect.)

I think that file doesn't expect Global power states, as thats only on,
sleeping, off, but sleep states. However I don't see the translation into PCI
sleep states either. But there must be some translation, as a 3 is translatet
into a 2 here (which than failes..)

I suppose some cleanup and documentation is required here.


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