Merge back PM core material for v4.16.

Documentation/driver-api/pm/devices.rst

@@ -788,6 +788,29 @@ must reflect the "active" status for runtime PM in that case.
 
 During system-wide resume from a sleep state it's easiest to put devices into
 the full-power state, as explained in :file:`Documentation/power/runtime_pm.txt`.
-Refer to that document for more information regarding this particular issue as
+[Refer to that document for more information regarding this particular issue as
 well as for information on the device runtime power management framework in
-general.
+general.]
+
+However, it often is desirable to leave devices in suspend after system
+transitions to the working state, especially if those devices had been in
+runtime suspend before the preceding system-wide suspend (or analogous)
+transition.  Device drivers can use the ``DPM_FLAG_LEAVE_SUSPENDED`` flag to
+indicate to the PM core (and middle-layer code) that they prefer the specific
+devices handled by them to be left suspended and they have no problems with
+skipping their system-wide resume callbacks for this reason.  Whether or not the
+devices will actually be left in suspend may depend on their state before the
+given system suspend-resume cycle and on the type of the system transition under
+way.  In particular, devices are not left suspended if that transition is a
+restore from hibernation, as device states are not guaranteed to be reflected
+by the information stored in the hibernation image in that case.
+
+The middle-layer code involved in the handling of the device is expected to
+indicate to the PM core if the device may be left in suspend by setting its
+:c:member:`power.may_skip_resume` status bit which is checked by the PM core
+during the "noirq" phase of the preceding system-wide suspend (or analogous)
+transition.  The middle layer is then responsible for handling the device as
+appropriate in its "noirq" resume callback, which is executed regardless of
+whether or not the device is left suspended, but the other resume callbacks
+(except for ``->complete``) will be skipped automatically by the PM core if the
+device really can be left in suspend.

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

drivers/acpi/device_pm.c

@@ -990,7 +990,7 @@ void acpi_subsys_complete(struct device *dev)
 	 * the sleep state it is going out of and it has never been resumed till
 	 * now, resume it in case the firmware powered it up.
 	 */
-	if (dev->power.direct_complete && pm_resume_via_firmware())
+	if (pm_runtime_suspended(dev) && pm_resume_via_firmware())
 		pm_request_resume(dev);
 }
 EXPORT_SYMBOL_GPL(acpi_subsys_complete);
@@ -1039,10 +1039,28 @@ EXPORT_SYMBOL_GPL(acpi_subsys_suspend_late);
  */
 int acpi_subsys_suspend_noirq(struct device *dev)
 {
-	if (dev_pm_smart_suspend_and_suspended(dev))
+	int ret;
+
+	if (dev_pm_smart_suspend_and_suspended(dev)) {
+		dev->power.may_skip_resume = true;
 		return 0;
+	}
+
+	ret = pm_generic_suspend_noirq(dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * 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
+	 * acpi_subsys_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 pm_generic_suspend_noirq(dev);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(acpi_subsys_suspend_noirq);
 
@@ -1052,6 +1070,9 @@ EXPORT_SYMBOL_GPL(acpi_subsys_suspend_noirq);
  */
 int acpi_subsys_resume_noirq(struct device *dev)
 {
+	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"

drivers/base/power/main.c

@@ -18,7 +18,6 @@
  */
 
 #include <linux/device.h>
-#include <linux/kallsyms.h>
 #include <linux/export.h>
 #include <linux/mutex.h>
 #include <linux/pm.h>
@@ -540,6 +539,18 @@ void dev_pm_skip_next_resume_phases(struct device *dev)
 	dev->power.is_suspended = false;
 }
 
+/**
+ * dev_pm_may_skip_resume - System-wide device resume optimization check.
+ * @dev: Target device.
+ *
+ * Checks whether or not the device may be left in suspend after a system-wide
+ * transition to the working state.
+ */
+bool dev_pm_may_skip_resume(struct device *dev)
+{
+	return !dev->power.must_resume && pm_transition.event != PM_EVENT_RESTORE;
+}
+
 /**
  * device_resume_noirq - Execute a "noirq resume" callback for given device.
  * @dev: Device to handle.
@@ -588,6 +599,18 @@ static int device_resume_noirq(struct device *dev, pm_message_t state, bool asyn
 	error = dpm_run_callback(callback, dev, state, info);
 	dev->power.is_noirq_suspended = false;
 
+	if (dev_pm_may_skip_resume(dev)) {
+		/*
+		 * The device is going to be left in suspend, but it might not
+		 * have been in runtime suspend before the system suspended, so
+		 * its runtime PM status needs to be updated to avoid confusing
+		 * the runtime PM framework when runtime PM is enabled for the
+		 * device again.
+		 */
+		pm_runtime_set_suspended(dev);
+		dev_pm_skip_next_resume_phases(dev);
+	}
+
  Out:
 	complete_all(&dev->power.completion);
 	TRACE_RESUME(error);
@@ -1089,6 +1112,22 @@ static pm_message_t resume_event(pm_message_t sleep_state)
 	return PMSG_ON;
 }
 
+static void dpm_superior_set_must_resume(struct device *dev)
+{
+	struct device_link *link;
+	int idx;
+
+	if (dev->parent)
+		dev->parent->power.must_resume = true;
+
+	idx = device_links_read_lock();
+
+	list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+		link->supplier->power.must_resume = true;
+
+	device_links_read_unlock(idx);
+}
+
 /**
  * __device_suspend_noirq - Execute a "noirq suspend" callback for given device.
  * @dev: Device to handle.
@@ -1140,10 +1179,28 @@ static int __device_suspend_noirq(struct device *dev, pm_message_t state, bool a
 	}
 
 	error = dpm_run_callback(callback, dev, state, info);
-	if (!error)
-		dev->power.is_noirq_suspended = true;
-	else
+	if (error) {
 		async_error = error;
+		goto Complete;
+	}
+
+	dev->power.is_noirq_suspended = true;
+
+	if (dev_pm_test_driver_flags(dev, DPM_FLAG_LEAVE_SUSPENDED)) {
+		/*
+		 * The only safe strategy here is to require that if the device
+		 * may not be left in suspend, resume callbacks must be invoked
+		 * for it.
+		 */
+		dev->power.must_resume = dev->power.must_resume ||
+					!dev->power.may_skip_resume ||
+					atomic_read(&dev->power.usage_count) > 1;
+	} else {
+		dev->power.must_resume = true;
+	}
+
+	if (dev->power.must_resume)
+		dpm_superior_set_must_resume(dev);
 
 Complete:
 	complete_all(&dev->power.completion);
@@ -1435,6 +1492,22 @@ static int legacy_suspend(struct device *dev, pm_message_t state,
 	return error;
 }
 
+static void dpm_propagate_to_parent(struct device *dev)
+{
+	struct device *parent = dev->parent;
+
+	if (!parent)
+		return;
+
+	spin_lock_irq(&parent->power.lock);
+
+	parent->power.direct_complete = false;
+	if (dev->power.wakeup_path && !parent->power.ignore_children)
+		parent->power.wakeup_path = true;
+
+	spin_unlock_irq(&parent->power.lock);
+}
+
 static void dpm_clear_suppliers_direct_complete(struct device *dev)
 {
 	struct device_link *link;
@@ -1500,6 +1573,9 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 		dev->power.direct_complete = false;
 	}
 
+	dev->power.may_skip_resume = false;
+	dev->power.must_resume = false;
+
 	dpm_watchdog_set(&wd, dev);
 	device_lock(dev);
 
@@ -1543,19 +1619,8 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
 
  End:
 	if (!error) {
-		struct device *parent = dev->parent;
-
 		dev->power.is_suspended = true;
-		if (parent) {
-			spin_lock_irq(&parent->power.lock);
-
-			dev->parent->power.direct_complete = false;
-			if (dev->power.wakeup_path
-			    && !dev->parent->power.ignore_children)
-				dev->parent->power.wakeup_path = true;
-
-			spin_unlock_irq(&parent->power.lock);
-		}
+		dpm_propagate_to_parent(dev);
 		dpm_clear_suppliers_direct_complete(dev);
 	}
 
@@ -1665,8 +1730,9 @@ static int device_prepare(struct device *dev, pm_message_t state)
 	if (dev->power.syscore)
 		return 0;
 
-	WARN_ON(dev_pm_test_driver_flags(dev, DPM_FLAG_SMART_SUSPEND) &&
-		!pm_runtime_enabled(dev));
+	WARN_ON(!pm_runtime_enabled(dev) &&
+		dev_pm_test_driver_flags(dev, DPM_FLAG_SMART_SUSPEND |
+					      DPM_FLAG_LEAVE_SUSPENDED));
 
 	/*
 	 * If a device's parent goes into runtime suspend at the wrong time,

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"

include/linux/pm.h

@@ -556,9 +556,10 @@ struct pm_subsys_data {
  * These flags can be set by device drivers at the probe time.  They need not be
  * cleared by the drivers as the driver core will take care of that.
  *
- * NEVER_SKIP: Do not skip system suspend/resume callbacks for the device.
+ * NEVER_SKIP: Do not skip all system suspend/resume callbacks for the device.
  * SMART_PREPARE: Check the return value of the driver's ->prepare callback.
  * SMART_SUSPEND: No need to resume the device from runtime suspend.
+ * LEAVE_SUSPENDED: Avoid resuming the device during system resume if possible.
  *
  * Setting SMART_PREPARE instructs bus types and PM domains which may want
  * system suspend/resume callbacks to be skipped for the device to return 0 from
@@ -572,10 +573,14 @@ struct pm_subsys_data {
  * necessary from the driver's perspective.  It also may cause them to skip
  * invocations of the ->suspend_late and ->suspend_noirq callbacks provided by
  * the driver if they decide to leave the device in runtime suspend.
+ *
+ * Setting LEAVE_SUSPENDED informs the PM core and middle-layer code that the
+ * driver prefers the device to be left in suspend after system resume.
  */
-#define DPM_FLAG_NEVER_SKIP	BIT(0)
-#define DPM_FLAG_SMART_PREPARE	BIT(1)
-#define DPM_FLAG_SMART_SUSPEND	BIT(2)
+#define DPM_FLAG_NEVER_SKIP		BIT(0)
+#define DPM_FLAG_SMART_PREPARE		BIT(1)
+#define DPM_FLAG_SMART_SUSPEND		BIT(2)
+#define DPM_FLAG_LEAVE_SUSPENDED	BIT(3)
 
 struct dev_pm_info {
 	pm_message_t		power_state;
@@ -597,6 +602,8 @@ struct dev_pm_info {
 	bool			wakeup_path:1;
 	bool			syscore:1;
 	bool			no_pm_callbacks:1;	/* Owned by the PM core */
+	unsigned int		must_resume:1;	/* Owned by the PM core */
+	unsigned int		may_skip_resume:1;	/* Set by subsystems */
 #else
 	unsigned int		should_wakeup:1;
 #endif
@@ -766,6 +773,7 @@ extern int pm_generic_poweroff(struct device *dev);
 extern void pm_generic_complete(struct device *dev);
 
 extern void dev_pm_skip_next_resume_phases(struct device *dev);
+extern bool dev_pm_may_skip_resume(struct device *dev);
 extern bool dev_pm_smart_suspend_and_suspended(struct device *dev);
 
 #else /* !CONFIG_PM_SLEEP */