On Wed, 25 Jun 2008, Rafael J. Wysocki wrote:
> Index: linux-2.6/drivers/pci/pci.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci.c
> +++ linux-2.6/drivers/pci/pci.c
> +/**
> + * pci_pme_active - enable or disable PCI device's PME# function
> + * @dev: PCI device to handle.
> + * @pm: PCI PM capability offset of the device.
> + * @enable: 'true' to enable PME# generation; 'false' to disable it.
> + *
> + * The caller must verify that the device is capable of generating PME# before
> + * calling this function with @enable equal to 'true'.
> + */
> +static void pci_pme_active(struct pci_dev *dev, int pm, bool enable)
> +{
> + u16 pmcsr;
> +
> + if (!pm)
> + return;
> +
> + pci_read_config_word(dev, pm + PCI_PM_CTRL, &pmcsr);
> + /* Clear PME_Status by writing 1 to it and enable PME# */
> + pmcsr |= PCI_PM_CTRL_PME_STATUS | PCI_PM_CTRL_PME_ENABLE;
> + if (!enable)
> + pmcsr &= ~PCI_PM_CTRL_PME_ENABLE;
> +
> + pci_write_config_word(dev, pm + PCI_PM_CTRL, pmcsr);
> +}
Question: Does the PME Status ever get cleared at any other times? For
instance, suppose a PCI device does use PME# to wake up the system.
Does its status get cleared?
Or suppose a PCI device is runtime-suspended and it generates a wakeup
request? This will turn on PME# at a time when the system isn't asleep
-- what happens then? Does it get lost somewhere in the bowels of
ACPI? Does the PCI core need new code to handle such things?
Alan Stern
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