On Monday, October 04, 2010, Matthew Garrett wrote:
> Not all hardware vendors hook up the PME line for legacy PCI devices,
> meaning that wakeup events get lost. The only way around this is to poll
> the devices to see if their state has changed, so add support for doing
> that on legacy PCI devices that aren't part of the core chipset.
>
> Signed-off-by: Matthew Garrett <mjg@xxxxxxxxxx>
Acked-by: Rafael J. Wysocki <rjw@xxxxxxx>
> ---
> drivers/pci/pci.c | 77 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 77 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 7fa3cbd..0b61263 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -38,6 +38,19 @@ EXPORT_SYMBOL(pci_pci_problems);
>
> unsigned int pci_pm_d3_delay;
>
> +static void pci_pme_list_scan(struct work_struct *work);
> +
> +static LIST_HEAD(pci_pme_list);
> +static DEFINE_MUTEX(pci_pme_list_mutex);
> +static DECLARE_DELAYED_WORK(pci_pme_work, pci_pme_list_scan);
> +
> +struct pci_pme_device {
> + struct list_head list;
> + struct pci_dev *dev;
> +};
> +
> +#define PME_TIMEOUT 1000 /* How long between PME checks */
> +
> static void pci_dev_d3_sleep(struct pci_dev *dev)
> {
> unsigned int delay = dev->d3_delay;
> @@ -1331,6 +1344,32 @@ bool pci_pme_capable(struct pci_dev *dev, pci_power_t state)
> return !!(dev->pme_support & (1 << state));
> }
>
> +static void pci_pme_list_scan(struct work_struct *work)
> +{
> + struct pci_pme_device *pme_dev;
> +
> + mutex_lock(&pci_pme_list_mutex);
> + if (!list_empty(&pci_pme_list)) {
> + list_for_each_entry(pme_dev, &pci_pme_list, list)
> + pci_pme_wakeup(pme_dev->dev, NULL);
> + schedule_delayed_work(&pci_pme_work, msecs_to_jiffies(PME_TIMEOUT));
> + }
> + mutex_unlock(&pci_pme_list_mutex);
> +}
> +
> +/**
> + * pci_external_pme - is a device an external PCI PME source?
> + * @dev: PCI device to check
> + *
> + */
> +
> +static bool pci_external_pme(struct pci_dev *dev)
> +{
> + if (pci_is_pcie(dev) || dev->bus->number == 0)
> + return false;
> + return true;
> +}
> +
> /**
> * pci_pme_active - enable or disable PCI device's PME# function
> * @dev: PCI device to handle.
> @@ -1354,6 +1393,44 @@ void pci_pme_active(struct pci_dev *dev, bool enable)
>
> pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, pmcsr);
>
> + /* PCI (as opposed to PCIe) PME requires that the device have
> + its PME# line hooked up correctly. Not all hardware vendors
> + do this, so the PME never gets delivered and the device
> + remains asleep. The easiest way around this is to
> + periodically walk the list of suspended devices and check
> + whether any have their PME flag set. The assumption is that
> + we'll wake up often enough anyway that this won't be a huge
> + hit, and the power savings from the devices will still be a
> + win. */
> +
> + if (pci_external_pme(dev)) {
> + struct pci_pme_device *pme_dev;
> + if (enable) {
> + pme_dev = kmalloc(sizeof(struct pci_pme_device),
> + GFP_KERNEL);
> + if (!pme_dev)
> + goto out;
> + pme_dev->dev = dev;
> + mutex_lock(&pci_pme_list_mutex);
> + list_add(&pme_dev->list, &pci_pme_list);
> + if (list_is_singular(&pci_pme_list))
> + schedule_delayed_work(&pci_pme_work,
> + msecs_to_jiffies(PME_TIMEOUT));
> + mutex_unlock(&pci_pme_list_mutex);
> + } else {
> + mutex_lock(&pci_pme_list_mutex);
> + list_for_each_entry(pme_dev, &pci_pme_list, list) {
> + if (pme_dev->dev == dev) {
> + list_del(&pme_dev->list);
> + kfree(pme_dev);
> + break;
> + }
> + }
> + mutex_unlock(&pci_pme_list_mutex);
> + }
> + }
> +
> +out:
> dev_printk(KERN_DEBUG, &dev->dev, "PME# %s\n",
> enable ? "enabled" : "disabled");
> }
>
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