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    SubjectRe: [RFC][PATCH 3/4] PCI / ACPI PM: Platform support for PCI PME wake-up (rev. 2)
    On Fri, Oct 09, 2009 at 12:54:18AM +0200, Rafael J. Wysocki wrote:

    > Unfortunately, the subset of PCI devices that have GPEs associated
    > with them is quite limited and the other devices have to rely on
    > the GPEs associated with their upstream bridges and, possibly, the
    > root bridge to generate ACPI wake-up events in response to PMEs from
    > them. Moreover, ACPI devices tend to share wake-up GPEs, in which
    > cases it makes sense to install an ACPI notify handler for only one
    > of them and "bind" the other devices to it. Furthermore, ACPI-based
    > PCI hotplug also uses ACPI notify handlers that in general may
    > conflict with the PM notify handlers, unless this issue is
    > specifically taken care of.

    I'm not sure this approach is correct - for instance, from a Dell
    system:

    Method (_L0D, 0, NotSerialized)
    {
    Store (SMI (0xC6, 0x00), Local0)
    If (And (Local0, 0x01))
    {
    Notify (\_SB.PCI0.AZAL, 0x02)
    }

    If (And (Local0, 0x02))
    {
    Notify (\_SB.PCI0.EHCI, 0x02)
    }

    If (And (Local0, 0x04))
    {
    Notify (\_SB.PCI0.EHC2, 0x02)
    }
    }

    All these devices share a GPE, but registering only one notify handler
    would result in us missing the notification in some cases. I also
    suspect that this should wait until the GPE rework is done.

    --
    Matthew Garrett | mjg59@srcf.ucam.org


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