BACKPORT: PM / sleep: Go direct_complete if driver has no callbacks

Backport notes: This resolves clk warnings in the designware i2c
driver on HiKey seen during suspend/resume.

Cherrypicked from: aa8e54b559479d0cb7eb632ba443b8cacd20cd4b

If a suitable prepare callback cannot be found for a given device and
its driver has no PM callbacks at all, assume that it can go direct to
complete when the system goes to sleep.

The reason for this is that there's lots of devices in a system that do
no PM at all and there's no reason for them to prevent their ancestors
to do direct_complete if they can support it.

Change-Id: Ia773afb4b266f012336b99fc8cf87453839e078b
Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[jstultz: Backported to 4.4]
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/drivers/base/dd.c b/drivers/base/dd.c
index a641cf3ccad691e76d9665e9defab4ef04e9af4f..9e425fbf83cbe0b342652b9976a334c93f5c2468 100644 (file)
--- a/drivers/base/dd.c
+++ b/drivers/base/dd.c
@@ -205,6 +205,8 @@ static void driver_bound(struct device *dev)
 
        klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
 
+       device_pm_check_callbacks(dev);
+
        /*
         * Make sure the device is no longer in one of the deferred lists and
         * kick off retrying all pending devices
@@ -697,6 +699,7 @@ static void __device_release_driver(struct device *dev)
                        dev->pm_domain->dismiss(dev);
 
                klist_remove(&dev->p->knode_driver);
+               device_pm_check_callbacks(dev);
                if (dev->bus)
                        blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
                                                     BUS_NOTIFY_UNBOUND_DRIVER,

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index d7fd724edb4d8ade02011d320b4beadc114d759b..7eea95d490e614d5cefaba9e870ebb8115a32f92 100644 (file)
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -126,6 +126,7 @@ void device_pm_add(struct device *dev)
 {
        pr_debug("PM: Adding info for %s:%s\n",
                 dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
+       device_pm_check_callbacks(dev);
        mutex_lock(&dpm_list_mtx);
        if (dev->parent && dev->parent->power.is_prepared)
                dev_warn(dev, "parent %s should not be sleeping\n",
@@ -148,6 +149,7 @@ void device_pm_remove(struct device *dev)
        mutex_unlock(&dpm_list_mtx);
        device_wakeup_disable(dev);
        pm_runtime_remove(dev);
+       device_pm_check_callbacks(dev);
 }
 
 /**
@@ -1575,6 +1577,11 @@ static int device_prepare(struct device *dev, pm_message_t state)
 
        dev->power.wakeup_path = device_may_wakeup(dev);
 
+       if (dev->power.no_pm_callbacks) {
+               ret = 1;        /* Let device go direct_complete */
+               goto unlock;
+       }
+
        if (dev->pm_domain) {
                info = "preparing power domain ";
                callback = dev->pm_domain->ops.prepare;
@@ -1597,6 +1604,7 @@ static int device_prepare(struct device *dev, pm_message_t state)
        if (callback)
                ret = callback(dev);
 
+unlock:
        device_unlock(dev);
 
        if (ret < 0) {
@@ -1725,3 +1733,30 @@ void dpm_for_each_dev(void *data, void (*fn)(struct device *, void *))
        device_pm_unlock();
 }
 EXPORT_SYMBOL_GPL(dpm_for_each_dev);
+
+static bool pm_ops_is_empty(const struct dev_pm_ops *ops)
+{
+       if (!ops)
+               return true;
+
+       return !ops->prepare &&
+              !ops->suspend &&
+              !ops->suspend_late &&
+              !ops->suspend_noirq &&
+              !ops->resume_noirq &&
+              !ops->resume_early &&
+              !ops->resume &&
+              !ops->complete;
+}
+
+void device_pm_check_callbacks(struct device *dev)
+{
+       spin_lock_irq(&dev->power.lock);
+       dev->power.no_pm_callbacks =
+               (!dev->bus || pm_ops_is_empty(dev->bus->pm)) &&
+               (!dev->class || pm_ops_is_empty(dev->class->pm)) &&
+               (!dev->type || pm_ops_is_empty(dev->type->pm)) &&
+               (!dev->pm_domain || pm_ops_is_empty(&dev->pm_domain->ops)) &&
+               (!dev->driver || pm_ops_is_empty(dev->driver->pm));
+       spin_unlock_irq(&dev->power.lock);
+}

diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index 998fa6b230844391b023b5ba8d4f0a22f9c645b0..297beae6431459458c509dcc4c497056156ddb64 100644 (file)
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -123,6 +123,7 @@ extern void device_pm_remove(struct device *);
 extern void device_pm_move_before(struct device *, struct device *);
 extern void device_pm_move_after(struct device *, struct device *);
 extern void device_pm_move_last(struct device *);
+extern void device_pm_check_callbacks(struct device *dev);
 
 #else /* !CONFIG_PM_SLEEP */
 
@@ -141,6 +142,8 @@ static inline void device_pm_move_after(struct device *deva,
                                        struct device *devb) {}
 static inline void device_pm_move_last(struct device *dev) {}
 
+static inline void device_pm_check_callbacks(struct device *dev) {}
+
 #endif /* !CONFIG_PM_SLEEP */
 
 static inline void device_pm_init(struct device *dev)

diff --git a/include/linux/pm.h b/include/linux/pm.h
index 528be6787796b52a405fbc0af8bf707c31d55192..6a5d654f444726abc824d9d07377ad66e86c6a44 100644 (file)
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -573,6 +573,7 @@ struct dev_pm_info {
        struct wakeup_source    *wakeup;
        bool                    wakeup_path:1;
        bool                    syscore:1;
+       bool                    no_pm_callbacks:1;      /* Owned by the PM core */
 #else
        unsigned int            should_wakeup:1;
 #endif