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SubjectRe: [linux-pm] [RFC,PATCHv3 0/3] sdhci runtime_pm implementation
On Wed, 2 Mar 2011, Rafael J. Wysocki wrote:

> > > How it works is, basically, that when the device signals wakeup, it either
> > > causes a PME# signal to be raised (parallel PCI), or a PME Message to be
> > > sent upstream (PCIe). In the first case it will cause a platform event
> > > (eg. ACPI GPE) to occur and the handle of that event will resume your
> > > device (using pm_request_resume()). In the second case it will cause the PCIe
> > > root port handling the PME Message to generate an interrupt and the handler of
> > > that interrupt will resume your device.
> > Thanks, that explain a lot how it works.
> > What I still dont understand is that the wake source I'll have (e.g.
> > sd card insert) is still an interrupt source.
> > So it is supposed to generate interrupt until the interrupt source is
> > acknowledged.
> > Are we supposed to mask that interrupt source while suspended to make
> > sure we have either wake or interrupt?
>
> I think the interrupt should be masked while suspended and the driver's resume
> routine should unmask it.

Right. That's how the PCI-based USB host controller drivers work.
The suspend routine disables interrupt generation and enables PME
wakeup signals, and the resume routine does the reverse.

Alan Stern



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