On Thursday 08 October 2009 04:52:48 pm Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@xxxxxxx>
>
> Add function pci_check_pme_status() that will check the PME status
> bit of given device and clear it along with the PME enable bit. It
> will be necessary for PCI run-time power management.
>
> Based on a patch from Shaohua Li <shaohua.li@xxxxxxxxx>
>
> Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> ---
> drivers/pci/pci.c | 35 +++++++++++++++++++++++++++++++++++
> drivers/pci/pci.h | 1 +
> 2 files changed, 36 insertions(+)
>
> Index: linux-2.6/drivers/pci/pci.h
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci.h
> +++ linux-2.6/drivers/pci/pci.h
> @@ -49,6 +49,7 @@ struct pci_platform_pm_ops {
> extern int pci_set_platform_pm(struct pci_platform_pm_ops *ops);
> extern void pci_update_current_state(struct pci_dev *dev, pci_power_t state);
> extern void pci_disable_enabled_device(struct pci_dev *dev);
> +extern bool pci_check_pme_status(struct pci_dev *dev);
> extern void pci_pm_init(struct pci_dev *dev);
> extern void platform_pci_wakeup_init(struct pci_dev *dev);
> extern void pci_allocate_cap_save_buffers(struct pci_dev *dev);
> Index: linux-2.6/drivers/pci/pci.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/pci.c
> +++ linux-2.6/drivers/pci/pci.c
> @@ -1167,6 +1167,41 @@ int pci_set_pcie_reset_state(struct pci_
> }
>
> /**
> + * pci_check_pme_status - Check if given device has generated PME.
> + * @dev: Device to check.
> + *
> + * Check the PME status of the device, clear PME status and PME enable. Return
> + * 'true' if PME has been generated by the device (and hasn't been spurious) or
> + * 'false' otherwise.
This comment confuses me because it implies that we always clear PME enable,
but that's not what the code does. If PME_STATUS is not asserted, the code
doesn't write anything.
> + */
> +bool pci_check_pme_status(struct pci_dev *dev)
> +{
> + int pmcsr_pos;
> + u16 pmcsr;
> + bool ret = false;
> +
> + if (!dev->pm_cap)
> + return false;
> +
> + pmcsr_pos = dev->pm_cap + PCI_PM_CTRL;
> + /* clear PME status and disable PME to avoid interrupt flood */
> + pci_read_config_word(dev, pmcsr_pos, &pmcsr);
> + if (!(pmcsr & PCI_PM_CTRL_PME_STATUS))
> + return false;
> +
> + pmcsr |= PCI_PM_CTRL_PME_STATUS;
> + /* Ignore spurious PME or clear PME enable if it's not spurious. */
> + if (pmcsr & PCI_PM_CTRL_PME_ENABLE) {
> + pmcsr &= ~PCI_PM_CTRL_PME_ENABLE;
> + ret = true;
> + }
> +
> + pci_write_config_word(dev, pmcsr_pos, pmcsr);
I can't tell whether the comment or the code is what was intended,
but I think the following would be a clearer way to implement the
comment:
pci_read_config_word(..., &pmcsr);
pci_write_config_word(..., (pmcsr | STATUS) & ~ENABLE);
if ((pmcsr & ENABLE) && (pmcsr & STATUS))
return true;
return false;
Bjorn
> +
> + return ret;
> +}
> +
> +/**
> * pci_pme_capable - check the capability of PCI device to generate PME#
> * @dev: PCI device to handle.
> * @state: PCI state from which device will issue PME#.
>
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