PCI / PM: Avoid resuming PCI devices during system suspend

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@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index cab05f31223f..7a671abceccc 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -521,6 +521,11 @@ static inline int platform_pci_run_wake(struct pci_dev *dev, bool enable)
                         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 *dev)
 }
 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;