On Thursday 27 August 2009, Shaohua Li wrote:
Hi,
> Add an implementation how to detect wakeup event for PCI. PCI device can
> invoke PME, platform or PCIe native approach can collect the event and
> report to OS. OS should identify exactly which device invokes PME as
> several devices can share PME pin.
>
> In platform approach (ACPI in this case), some BIOS give exact device which
> invokes PME but others doesn't. In either case, we always scan all devices
> to check which one is the wakeup source. In the meantime, if the device isn't a
> bridge, we trust the device is wakeup source even its PME status isn't set,
> because BIOS can clear PME status before OS gets notification and we have no
> reliable method to check if the device is the wakeup source.
>
> In PCIe native approach, if PME source device is a pcie endpoint, the device
> is the exact PME source. If the device is root port or pcie-to-pci bridge,
> we need scan legacy devices in the hierarchy under the root port or bridge.
>
> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
> ---
> drivers/pci/pci-driver.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++
> drivers/pci/pci.h | 3 +
> 2 files changed, 109 insertions(+)
>
> Index: linux/drivers/pci/pci-driver.c
> ===================================================================
> --- linux.orig/drivers/pci/pci-driver.c 2009-08-25 15:39:52.000000000 +0800
> +++ linux/drivers/pci/pci-driver.c 2009-08-27 14:15:34.000000000 +0800
> @@ -17,6 +17,7 @@
> #include <linux/slab.h>
> #include <linux/sched.h>
> #include <linux/cpu.h>
> +#include <linux/pm_runtime.h>
> #include "pci.h"
>
> /*
> @@ -570,6 +571,111 @@ static void pci_pm_complete(struct devic
> drv->pm->complete(dev);
> }
>
> +/*
> + * pci_pm_check_wakeup_event - pdev is suspected to invoke a wakeup event
> + * @pdev: the suspected pci device
> + *
> + * Clear PME status and disable PME, return if the pci device @pdev really
> + * invokes PME
> + **/
> +static bool pci_pm_check_wakeup_event(struct pci_dev *pdev)
> +{
> + int pme_pos = pdev->pm_cap;
> + u16 pmcsr;
> + bool ret = false;
> +
> + if (!pme_pos)
> + return false;
> +
> + /* clear PME status and disable PME to avoid interrupt flood */
> + pci_read_config_word(pdev, pme_pos + PCI_PM_CTRL, &pmcsr);
> + if (!(pmcsr & PCI_PM_CTRL_PME_STATUS))
> + return false;
> +
> + /* I see spurious PME here, just ignore it for now */
> + if (pmcsr & PCI_PM_CTRL_PME_ENABLE) {
> + pmcsr &= ~PCI_PM_CTRL_PME_ENABLE;
> + ret = true;
> + }
> +
> + pmcsr |= PCI_PM_CTRL_PME_STATUS;
> + pci_write_config_word(pdev, pme_pos + PCI_PM_CTRL, pmcsr);
> +
> + return ret;
> +}
The function above looks good.
I think it's better to move the one below into the PCIe PME code.
> +
> +/*
> + * pci_pm_handle_wakeup_event_native - handle PCIe native PME event
> + * @target is suspected to invoke a wakeup event (PME)
> + * Note @target should be a PCIe device
> + */
> +bool pci_pm_handle_wakeup_event_native(struct pci_dev *target)
> +{
> + bool ret;
> + struct pci_dev *tmp = NULL;
> + int domain_nr, bus_start, bus_end;
> +
> + BUG_ON(!target->is_pcie);
> +
> + /* For PCIe PME, if the target isn't the source, do nothing */
> + ret = pci_pm_check_wakeup_event(target);
> +
> + if (!target->subordinate || (target->pcie_type != PCI_EXP_TYPE_ROOT_PORT
> + && target->pcie_type != PCI_EXP_TYPE_PCI_BRIDGE)) {
> + if (ret)
> + pm_runtime_resume(&target->dev);
> + return ret;
> + }
> +
> + if (ret)
> + pm_request_resume(&target->dev);
Here, if you want to busy loop in pcie_pme_work_handle(), it's better not to
use pm_runtime_resume() (sorry, I overlooked that before), because we should
first clear all PME_Status flags set and _then_ try to resume the devices.
So, the code you had here before was better:
+ ret = pci_pm_check_wakeup_event(target);
+ if (ret)
+ pm_request_resume(&target->dev);
+ if (is_regular_device(target))
+ return ret;
> +
> + /* scan legacy PCI devices under the bridge or root port */
> + domain_nr = pci_domain_nr(target->bus);
> + bus_start = target->subordinate->secondary;
> + bus_end = target->subordinate->subordinate;
> + while ((tmp = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, tmp)) != NULL) {
> + if (pci_domain_nr(tmp->bus) == domain_nr &&
> + tmp->bus->number >= bus_start &&
> + tmp->bus->number <= bus_end) {
> + if (!tmp->is_pcie && pci_pm_check_wakeup_event(tmp)) {
> + ret = true;
> + pm_request_resume(&tmp->dev);
> + }
Do we have to check ->is_pcie here?
Anyway, I'd do
+ if (pci_domain_nr(tmp->bus) != domain_nr
+ || tmp->bus->number < bus_start || tmp->bus->number > bus_end)
+ continue;
and then the rest.
> + }
> + }
> + return ret;
> +}
> +
> +/*
> + * pci_pm_handle_wakeup_event_platform - handle platform PCI wakeup event
> + * @target is suspected to invoke a wakeup event
> + */
> +bool pci_pm_handle_wakeup_event_platform(struct pci_dev *target)
> +{
> + bool ret = false;
> + struct pci_dev *tmp = NULL;
> +
> + /*
> + * In the platform approach (ACPI), target PME status might get cleared
> + * by BIOS before OS receives a notification, so we haven't reliable
> + * method to detect if target is the wakeup source, just trust it is
> + */
> + pci_pm_check_wakeup_event(target);
> + pm_request_resume(&target->dev);
> + if (!target->subordinate)
> + ret = true;
> +
> + /* scan all pci devices to find the wakeup source */
> + while ((tmp = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, tmp)) != NULL) {
Doing
+ if (tmp == target)
+ continue;
separately would be cleaner IMO.
> + if (tmp != target && pci_pm_check_wakeup_event(tmp)) {
> + ret = true;
> + pm_request_resume(&tmp->dev);
> + }
> + }
> + return ret;
> +}
> +
> #ifdef CONFIG_SUSPEND
>
> static int pci_pm_suspend(struct device *dev)
> Index: linux/drivers/pci/pci.h
> ===================================================================
> --- linux.orig/drivers/pci/pci.h 2009-08-25 15:38:50.000000000 +0800
> +++ linux/drivers/pci/pci.h 2009-08-26 09:07:42.000000000 +0800
> @@ -83,6 +83,9 @@ static inline void pci_vpd_release(struc
> dev->vpd->ops->release(dev);
> }
>
> +extern bool pci_pm_handle_wakeup_event_native(struct pci_dev *target);
> +extern bool pci_pm_handle_wakeup_event_platform(struct pci_dev *target);
> +
> /* PCI /proc functions */
> #ifdef CONFIG_PROC_FS
> extern int pci_proc_attach_device(struct pci_dev *dev);
>
>
Thanks,
Rafael
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