Re: [linux-pm] Re: ehci_hcd causes box to resume immediately after suspend to RAM

Alan Stern <[email protected]>
Newsgroups gmane.linux.usb.devel,gmane.linux.power-management.general
Message-ID <[email protected]>
On Tue, 25 Sep 2007, Benjamin Herrenschmidt wrote:

> > That's odd.  Where could these overcurrent changes be coming from?  
> > And how come they don't show up on ports 1 and 2?
> > 
> > There's an excellent chance that they are responsible for your 
> > immediate resumes.
> 
> I've seen quirks in Apple drivers a while ago where they tried to avoid
> suspending some of the RH ports... possibly bcs they aren't connected to
> anything and trying to suspend them does bad things.

That is certainly possible.  I have seen exactly the same sort of thing
on some HP systems, where (1) the overcurrent inputs for unused ports
are permanently wired high, and (2) a bug in the Intel UHCI controller
causes a resume event whenever any port has an overcurrent condition!

>  I wonder if maybe
> ACPI might carry similar kind of informations...

I wouldn't know where to look.

Alan Stern


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