Re: ehci_hcd causes box to resume immediately after suspend to RAM

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Sunday, 3 June 2007 17:31, Alan Stern wrote:
> On Sun, 3 Jun 2007, Rafael J. Wysocki wrote:
> 
> > Hi,
> > 
> > One of my test boxes suspends to RAM just fine except that if ehci_hcd is
> > loaded before the suspend, the box resumes immediately after going to sleep.
> 
> Evidently the hardware thinks a wakeup event has occurred.  It is 
> possible to disable remote wakeup via sysfs, but it would be more 
> interesting to find out the real reason for the wakeup.
> 
> I don't know how to go about doing that, however.  It might be some 
> interaction at the ACPI level, and it might involve the PCI PME# 
> signal.
> 
> Do you have any USB devices attached when you suspend?
> 
> You can try using the patch below to see what happens when you manually
> suspend the controller.  It enables PCI devices to respond to the
> legacy power/state attribute.  You should look at what "lspci -vv" says
> about the controller's power management signals, both before and after
> suspending the PCI device entry.

It works as expected, AFAICS.  That is, after I echo '2' to the 'state' file,
it shows that the controller is in D3.

I've tried to suspend with the controller in that state, but it's resumed
immediately, as before.

> Maybe also see what ACPI reports.

How can I see that?

Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth

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