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.
/*------------------------- Resume routines -------------------------*/
/**
+ * 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.
* @state: PM transition of the system being carried out.
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->power.is_late_suspended = false;
+ dev->power.is_suspended = false;
+ }
+
Out:
complete_all(&dev->power.completion);
TRACE_RESUME(error);
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.
}
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);
dev->power.direct_complete = false;
}
+ dev->power.may_skip_resume = false;
+ dev->power.must_resume = false;
+
dpm_watchdog_set(&wd, dev);
device_lock(dev);
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,
* 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
* 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;
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
extern int pm_generic_poweroff(struct device *dev);
extern void pm_generic_complete(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 */
projects / platform / kernel / linux-rpi.git / commitdiff