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SubjectRe: [PATCH 2/12] PCI / PM: Propagate wake-up enable for PCIe devices too
Date
On Tuesday 05 January 2010, Jesse Barnes wrote:
> On Sun, 27 Dec 2009 21:00:33 +0100
> "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
>
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> >
> > Having read the PM part of the PCIe 2.0 specification more carefully
> > I think that it was a mistake to restrict the wake-up enable
> > propagation to non-PCIe devices, because if we do not request
> > control of the root ports' PME registers via OSC, PCIe PME is
> > supposed to be handled by the platform, just like the non-PCIe PME.
> > Even if we do that, the wake-up propagation is done to allow the
> > devices to wake up the system from sleep states which involves the
> > platform anyway, so it won't hurt.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> > ---
> > drivers/pci/pci-acpi.c | 10 ++--------
> > 1 file changed, 2 insertions(+), 8 deletions(-)
> >
> > Index: linux-2.6/drivers/pci/pci-acpi.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/pci/pci-acpi.c
> > +++ linux-2.6/drivers/pci/pci-acpi.c
> > @@ -112,11 +112,7 @@ static bool acpi_pci_can_wakeup(struct p
> > static void acpi_pci_propagate_wakeup_enable(struct pci_bus *bus,
> > bool enable) {
> > while (bus->parent) {
> > - struct pci_dev *bridge = bus->self;
> > - int ret;
> > -
> > - ret = acpi_pm_device_sleep_wake(&bridge->dev,
> > enable);
> > - if (!ret || pci_is_pcie(bridge))
> > + if (!acpi_pm_device_sleep_wake(&bus->self->dev,
> > enable)) return;
> > bus = bus->parent;
> > }
> > @@ -131,9 +127,7 @@ static int acpi_pci_sleep_wake(struct pc
> > if (acpi_pci_can_wakeup(dev))
> > return acpi_pm_device_sleep_wake(&dev->dev, enable);
> >
> > - if (!pci_is_pcie(dev))
> > - acpi_pci_propagate_wakeup_enable(dev->bus, enable);
> > -
> > + acpi_pci_propagate_wakeup_enable(dev->bus, enable);
> > return 0;
> > }
>
> Seems ok to try it out, but as usual with this sort of thing, the real
> question is, "What does Windows do?", since wakeup enable ACPI support
> for PCIe devices is likely broken unless Windows uses it.

Well, that's in the Linus' tree already, so I guess we're going to learn. ;-)

Seriously, I think that Windows actually uses ACPI wake-up support for PCIe
devices. On my Toshiba Portege R500 the BIOS doesn't even allow us to use
the native PCIe PME mechanism directly, so the patch is correct IMO.

Rafael


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