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    Subject[RFC PATCH] PCIe: Add PCIe runtime D3cold support
    Hi all,

    This patch adds PCIe runtime D3cold support, namely cut power supply for functions
    beneath a PCIe port when they all have entered D3. A device in D3cold can only
    generate wake event through the WAKE# pin. Because we can not access to a device's
    configure space while it's in D3cold, pme_poll is disabled for devices in D3cold.

    Any comment will be appreciated.

    Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
    ---
    diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
    index 0f150f2..e210e8cb 100644
    --- a/drivers/pci/pci-acpi.c
    +++ b/drivers/pci/pci-acpi.c
    @@ -224,7 +224,7 @@ static int acpi_pci_set_power_state(struct pci_dev *dev, pci_power_t state)
    [PCI_D1] = ACPI_STATE_D1,
    [PCI_D2] = ACPI_STATE_D2,
    [PCI_D3hot] = ACPI_STATE_D3,
    - [PCI_D3cold] = ACPI_STATE_D3
    + [PCI_D3cold] = ACPI_STATE_D3_COLD
    };
    int error = -EINVAL;

    @@ -296,7 +296,8 @@ static void acpi_pci_propagate_run_wake(struct pci_bus *bus, bool enable)

    static int acpi_pci_run_wake(struct pci_dev *dev, bool enable)
    {
    - if (dev->pme_interrupt)
    + /* PME interrupt isn't available in the D3cold case */
    + if (dev->pme_interrupt && !dev->runtime_d3cold)
    return 0;

    if (!acpi_pm_device_run_wake(&dev->dev, enable))
    diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
    index 8156744..bc16869 100644
    --- a/drivers/pci/pci.c
    +++ b/drivers/pci/pci.c
    @@ -731,8 +731,8 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
    int error;

    /* bound the state we're entering */
    - if (state > PCI_D3hot)
    - state = PCI_D3hot;
    + if (state > PCI_D3cold)
    + state = PCI_D3cold;
    else if (state < PCI_D0)
    state = PCI_D0;
    else if ((state == PCI_D1 || state == PCI_D2) && pci_no_d1d2(dev))
    @@ -750,7 +750,8 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
    if (state == PCI_D3hot && (dev->dev_flags & PCI_DEV_FLAGS_NO_D3))
    return 0;

    - error = pci_raw_set_power_state(dev, state);
    + error = pci_raw_set_power_state(dev, state > PCI_D3hot ?
    + PCI_D3hot : state);

    if (!__pci_complete_power_transition(dev, state))
    error = 0;
    @@ -1482,6 +1483,17 @@ bool pci_pme_capable(struct pci_dev *dev, pci_power_t state)
    return !!(dev->pme_support & (1 << state));
    }

    +static void pci_pme_poll_wakeup(struct pci_dev *dev)
    +{
    + struct pci_dev *bridge = dev->bus->self;
    +
    + /* don't poll the pme bit if parent is in low power state */
    + if (bridge && bridge->current_state != PCI_D0)
    + return;
    +
    + pci_pme_wakeup(dev, NULL);
    +}
    +
    static void pci_pme_list_scan(struct work_struct *work)
    {
    struct pci_pme_device *pme_dev, *n;
    @@ -1490,7 +1502,7 @@ static void pci_pme_list_scan(struct work_struct *work)
    if (!list_empty(&pci_pme_list)) {
    list_for_each_entry_safe(pme_dev, n, &pci_pme_list, list) {
    if (pme_dev->dev->pme_poll) {
    - pci_pme_wakeup(pme_dev->dev, NULL);
    + pci_pme_poll_wakeup(pme_dev->dev);
    } else {
    list_del(&pme_dev->list);
    kfree(pme_dev);
    @@ -1608,6 +1620,10 @@ int __pci_enable_wake(struct pci_dev *dev, pci_power_t state,
    if (enable) {
    int error;

    + if (runtime && state >= PCI_D3cold)
    + dev->runtime_d3cold = true;
    + else
    + dev->runtime_d3cold = false;
    if (pci_pme_capable(dev, state))
    pci_pme_active(dev, true);
    else
    diff --git a/drivers/pci/pcie/portdrv_pci.c b/drivers/pci/pcie/portdrv_pci.c
    index e0610bd..d66b7e9 100644
    --- a/drivers/pci/pcie/portdrv_pci.c
    +++ b/drivers/pci/pcie/portdrv_pci.c
    @@ -11,11 +11,13 @@
    #include <linux/kernel.h>
    #include <linux/errno.h>
    #include <linux/pm.h>
    +#include <linux/pm_runtime.h>
    #include <linux/init.h>
    #include <linux/pcieport_if.h>
    #include <linux/aer.h>
    #include <linux/dmi.h>
    #include <linux/pci-aspm.h>
    +#include <linux/delay.h>

    #include "portdrv.h"
    #include "aer/aerdrv.h"
    @@ -99,6 +101,25 @@ static int pcie_port_resume_noirq(struct device *dev)
    return 0;
    }

    +static int pcie_port_runtime_suspend(struct device *dev)
    +{
    + struct pci_dev *pdev = to_pci_dev(dev);
    +
    + pci_save_state(pdev);
    + return 0;
    +}
    +
    +static int pcie_port_runtime_resume(struct device *dev)
    +{
    + struct pci_dev *pdev = to_pci_dev(dev);
    +
    + pci_restore_state(pdev);
    + if (pdev->runtime_d3cold)
    + msleep(100);
    +
    + return 0;
    +}
    +
    static const struct dev_pm_ops pcie_portdrv_pm_ops = {
    .suspend = pcie_port_device_suspend,
    .resume = pcie_port_device_resume,
    @@ -107,6 +128,8 @@ static const struct dev_pm_ops pcie_portdrv_pm_ops = {
    .poweroff = pcie_port_device_suspend,
    .restore = pcie_port_device_resume,
    .resume_noirq = pcie_port_resume_noirq,
    + .runtime_suspend = pcie_port_runtime_suspend,
    + .runtime_resume = pcie_port_runtime_resume,
    };

    #define PCIE_PORTDRV_PM_OPS (&pcie_portdrv_pm_ops)
    @@ -144,12 +167,14 @@ static int __devinit pcie_portdrv_probe(struct pci_dev *dev,
    return status;

    pci_save_state(dev);
    + pm_runtime_put_noidle(&dev->dev);

    return 0;
    }

    static void pcie_portdrv_remove(struct pci_dev *dev)
    {
    + pm_runtime_get_noresume(&dev->dev);
    pcie_port_device_remove(dev);
    pci_disable_device(dev);
    }
    diff --git a/include/linux/pci.h b/include/linux/pci.h
    index e444f5b..b41d9a1 100644
    --- a/include/linux/pci.h
    +++ b/include/linux/pci.h
    @@ -281,6 +281,7 @@ struct pci_dev {
    unsigned int no_d1d2:1; /* Only allow D0 and D3 */
    unsigned int mmio_always_on:1; /* disallow turning off io/mem
    decoding during bar sizing */
    + unsigned int runtime_d3cold:1;
    unsigned int wakeup_prepared:1;
    unsigned int d3_delay; /* D3->D0 transition time in ms */


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