PCI / PM: Support for LEAVE_SUSPENDED driver flag

Add support for DPM_FLAG_LEAVE_SUSPENDED to the PCI bus type by
making it (a) set the power.may_skip_resume status bit for devices
that, from its perspective, may be left in suspend after system
wakeup from sleep and (b) return early from pci_pm_resume_noirq()
for devices whose remaining resume callbacks during the transition
under way are going to be skipped by the PM core.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>

diff --git a/Documentation/power/pci.txt b/Documentation/power/pci.txt
index 704cd36..8eaf9ee 100644 (file)
--- a/Documentation/power/pci.txt
+++ b/Documentation/power/pci.txt
@@ -994,6 +994,17 @@ into D0 going forward), but if it is in runtime suspend in pci_pm_thaw_noirq(),
 the function will set the power.direct_complete flag for it (to make the PM core
 skip the subsequent "thaw" callbacks for it) and return.
 
+Setting the DPM_FLAG_LEAVE_SUSPENDED flag means that the driver prefers the
+device to be left in suspend after system-wide transitions to the working state.
+This flag is checked by the PM core, but the PCI bus type informs the PM core
+which devices may be left in suspend from its perspective (that happens during
+the "noirq" phase of system-wide suspend and analogous transitions) and next it
+uses the dev_pm_may_skip_resume() helper to decide whether or not to return from
+pci_pm_resume_noirq() early, as the PM core will skip the remaining resume
+callbacks for the device during the transition under way and will set its
+runtime PM status to "suspended" if dev_pm_may_skip_resume() returns "true" for
+it.
+
 3.2. Device Runtime Power Management
 ------------------------------------
 In addition to providing device power management callbacks PCI device drivers

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 7f47bb7..3cf2da2 100644 (file)
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -699,7 +699,7 @@ static void pci_pm_complete(struct device *dev)
        pm_generic_complete(dev);
 
        /* Resume device if platform firmware has put it in reset-power-on */
-       if (dev->power.direct_complete && pm_resume_via_firmware()) {
+       if (pm_runtime_suspended(dev) && pm_resume_via_firmware()) {
                pci_power_t pre_sleep_state = pci_dev->current_state;
 
                pci_update_current_state(pci_dev, pci_dev->current_state);
@@ -783,8 +783,10 @@ static int pci_pm_suspend_noirq(struct device *dev)
        struct pci_dev *pci_dev = to_pci_dev(dev);
        const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
 
-       if (dev_pm_smart_suspend_and_suspended(dev))
+       if (dev_pm_smart_suspend_and_suspended(dev)) {
+               dev->power.may_skip_resume = true;
                return 0;
+       }
 
        if (pci_has_legacy_pm_support(pci_dev))
                return pci_legacy_suspend_late(dev, PMSG_SUSPEND);
@@ -838,6 +840,16 @@ static int pci_pm_suspend_noirq(struct device *dev)
 Fixup:
        pci_fixup_device(pci_fixup_suspend_late, pci_dev);
 
+       /*
+        * If the target system sleep state is suspend-to-idle, it is sufficient
+        * to check whether or not the device's wakeup settings are good for
+        * runtime PM.  Otherwise, the pm_resume_via_firmware() check will cause
+        * pci_pm_complete() to take care of fixing up the device's state
+        * anyway, if need be.
+        */
+       dev->power.may_skip_resume = device_may_wakeup(dev) ||
+                                       !device_can_wakeup(dev);
+
        return 0;
 }
 
@@ -847,6 +859,9 @@ static int pci_pm_resume_noirq(struct device *dev)
        struct device_driver *drv = dev->driver;
        int error = 0;
 
+       if (dev_pm_may_skip_resume(dev))
+               return 0;
+
        /*
         * Devices with DPM_FLAG_SMART_SUSPEND may be left in runtime suspend
         * during system suspend, so update their runtime PM status to "active"