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Date: Fri, 23 Jan 2015 14:55:25 -0600
From: Bjorn Helgaas <bhelgaas@...gle.com>
To: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Linux PCI <linux-pci@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux PM list <linux-pm@...r.kernel.org>,
Alan Stern <stern@...land.harvard.edu>,
Aaron Lu <aaron.lu@...el.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH][v3] PCI / PM: Avoid resuming PCI devices during system suspend
On Tue, Jan 20, 2015 at 7:17 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>
> Commit f25c0ae2b4c4 (ACPI / PM: Avoid resuming devices in ACPI PM
> domain during system suspend) modified the ACPI PM domain's system
> suspend callbacks to allow devices attached to it to be left in the
> runtime-suspended state during system suspend so as to optimize
> the suspend process.
>
> This was based on the general mechanism introduced by commit
> aae4518b3124 (PM / sleep: Mechanism to avoid resuming runtime-suspended
> devices unnecessarily).
>
> Extend that approach to PCI devices by modifying the PCI bus type's
> ->prepare callback to return 1 for devices that are runtime-suspended
> when it is being executed and that are in a suitable power state and
> need not be resumed going forward.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
I don't profess to understand this, and it seems like something you
could merge via your PM tree. So I trust you to do the right thing
with it :)
Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>
> This version actually builds and need not be an RFC any more I suppose.
>
> ---
> drivers/pci/pci-acpi.c | 17 +++++++++++++++++
> drivers/pci/pci-driver.c | 11 ++++++-----
> drivers/pci/pci.c | 26 ++++++++++++++++++++++++++
> drivers/pci/pci.h | 6 ++++++
> 4 files changed, 55 insertions(+), 5 deletions(-)
>
> Index: linux-pm/drivers/pci/pci.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci.c
> +++ linux-pm/drivers/pci/pci.c
> @@ -521,6 +521,11 @@ static inline int platform_pci_run_wake(
> pci_platform_pm->run_wake(dev, enable) : -ENODEV;
> }
>
> +static inline bool platform_pci_need_resume(struct pci_dev *dev)
> +{
> + return pci_platform_pm ? pci_platform_pm->need_resume(dev) : false;
> +}
> +
> /**
> * pci_raw_set_power_state - Use PCI PM registers to set the power state of
> * given PCI device
> @@ -1999,6 +2004,27 @@ bool pci_dev_run_wake(struct pci_dev *de
> }
> EXPORT_SYMBOL_GPL(pci_dev_run_wake);
>
> +/**
> + * pci_dev_keep_suspended - Check if the device can stay in the suspended state.
> + * @pci_dev: Device to check.
> + *
> + * Return 'true' if the device is runtime-suspended, it doesn't have to be
> + * reconfigured due to wakeup settings difference between system and runtime
> + * suspend and the current power state of it is suitable for the upcoming
> + * (system) transition.
> + */
> +bool pci_dev_keep_suspended(struct pci_dev *pci_dev)
> +{
> + struct device *dev = &pci_dev->dev;
> +
> + if (!pm_runtime_suspended(dev)
> + || (device_can_wakeup(dev) && !device_may_wakeup(dev))
> + || platform_pci_need_resume(pci_dev))
> + return false;
> +
> + return pci_target_state(pci_dev) == pci_dev->current_state;
> +}
> +
> void pci_config_pm_runtime_get(struct pci_dev *pdev)
> {
> struct device *dev = &pdev->dev;
> Index: linux-pm/drivers/pci/pci.h
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci.h
> +++ linux-pm/drivers/pci/pci.h
> @@ -50,6 +50,10 @@ int pci_probe_reset_function(struct pci_
> * for given device (the device's wake-up capability has to be
> * enabled by @sleep_wake for this feature to work)
> *
> + * @need_resume: returns 'true' if the given device (which is currently
> + * suspended) needs to be resumed to be configured for system
> + * wakeup.
> + *
> * If given platform is generally capable of power managing PCI devices, all of
> * these callbacks are mandatory.
> */
> @@ -59,6 +63,7 @@ struct pci_platform_pm_ops {
> pci_power_t (*choose_state)(struct pci_dev *dev);
> int (*sleep_wake)(struct pci_dev *dev, bool enable);
> int (*run_wake)(struct pci_dev *dev, bool enable);
> + bool (*need_resume)(struct pci_dev *dev);
> };
>
> int pci_set_platform_pm(struct pci_platform_pm_ops *ops);
> @@ -67,6 +72,7 @@ void pci_power_up(struct pci_dev *dev);
> void pci_disable_enabled_device(struct pci_dev *dev);
> int pci_finish_runtime_suspend(struct pci_dev *dev);
> int __pci_pme_wakeup(struct pci_dev *dev, void *ign);
> +bool pci_dev_keep_suspended(struct pci_dev *dev);
> void pci_config_pm_runtime_get(struct pci_dev *dev);
> void pci_config_pm_runtime_put(struct pci_dev *dev);
> void pci_pm_init(struct pci_dev *dev);
> Index: linux-pm/drivers/pci/pci-acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci-acpi.c
> +++ linux-pm/drivers/pci/pci-acpi.c
> @@ -501,12 +501,29 @@ static int acpi_pci_run_wake(struct pci_
> return 0;
> }
>
> +static bool acpi_pci_need_resume(struct pci_dev *dev)
> +{
> + struct acpi_device *adev = ACPI_COMPANION(&dev->dev);
> +
> + if (!adev || !acpi_device_power_manageable(adev))
> + return false;
> +
> + if (device_may_wakeup(&dev->dev) != !!adev->wakeup.prepare_count)
> + return true;
> +
> + if (acpi_target_system_state() == ACPI_STATE_S0)
> + return false;
> +
> + return !!adev->power.flags.dsw_present;
> +}
> +
> static struct pci_platform_pm_ops acpi_pci_platform_pm = {
> .is_manageable = acpi_pci_power_manageable,
> .set_state = acpi_pci_set_power_state,
> .choose_state = acpi_pci_choose_state,
> .sleep_wake = acpi_pci_sleep_wake,
> .run_wake = acpi_pci_run_wake,
> + .need_resume = acpi_pci_need_resume,
> };
>
> void acpi_pci_add_bus(struct pci_bus *bus)
> Index: linux-pm/drivers/pci/pci-driver.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci-driver.c
> +++ linux-pm/drivers/pci/pci-driver.c
> @@ -653,7 +653,6 @@ static bool pci_has_legacy_pm_support(st
> static int pci_pm_prepare(struct device *dev)
> {
> struct device_driver *drv = dev->driver;
> - int error = 0;
>
> /*
> * Devices having power.ignore_children set may still be necessary for
> @@ -662,10 +661,12 @@ static int pci_pm_prepare(struct device
> if (dev->power.ignore_children)
> pm_runtime_resume(dev);
>
> - if (drv && drv->pm && drv->pm->prepare)
> - error = drv->pm->prepare(dev);
> -
> - return error;
> + if (drv && drv->pm && drv->pm->prepare) {
> + int error = drv->pm->prepare(dev);
> + if (error)
> + return error;
> + }
> + return pci_dev_keep_suspended(to_pci_dev(dev));
> }
>
>
>
--
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