On Tue, 9 Sep 2008, David Brownell wrote:
> > (As a matter of fact, I have no idea whether or not Intel's legacy PM
> > for UHCI is implemented in AML. It may vary from one BIOS to another.)
>
> One data point: on the laptop used to type this message,
> the GPE code block includes stuff like this for each UHCI:
>
> Method (_L0C, 0, NotSerialized)
> {
> Notify (\_SB.PCI0.USB3, 0x02)
> }
>
> Without diving into the ICHx specs (which I believe DO have
> such details, thanks be!), my first reaction is that this is
> not a "case (c)". Of course, the rest of the AML code is,
> as usual, cryptic (I'd rather have C code), and such stuff
> might be hidden elsewhere in the event sequence.
Fortunately the interface is extremely simple. It's an 8-bit register
in the PCI config space, where the two low-order bits enable
wakeup detection for each of the two ports. It won't matter if the
driver and the AML both try to disable wakeup; the end result should
work regardless.
Anyway, the real problem here is not to enable or disable wakeup
detection. It is to determine whether or not the device really did
issue a wakeup request. With Intel's UHCI this involves reading an I/O
register. On all the systems I have tried it works even in D3hot, so
we should be okay.
Alan Stern
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