PM / Runtime: Use device PM QoS constraints

Make the runtime PM core use device PM QoS constraints to check if
it is allowed to suspend a given device, so that an error code is
returned if the device's own PM QoS constraint is negative or one of
its children has already been suspended for too long.  If this is
not the case, the maximum estimated time the device is allowed to be
suspended, computed as the minimum of the device's PM QoS constraint
and the PM QoS constraints of its children (reduced by the difference
between the current time and their suspend times) is stored in a new
device's PM field power.max_time_suspended_ns that can be used by
the device's subsystem or PM domain to decide whether or not to put
the device into lower-power (and presumably higher-latency) states
later (if the constraint is 0, which means "no constraint", the
power.max_time_suspended_ns is set to -1).

Additionally, the time of execution of the subsystem-level
.runtime_suspend() callback for the device is recorded in the new
power.suspend_time field for later use by the device's subsystem or
PM domain along with power.max_time_suspended_ns (it also is used
by the core code when the device's parent is suspended).

Introduce a new helper function,
pm_runtime_update_max_time_suspended(), allowing subsystems and PM
domains (or device drivers) to update the power.max_time_suspended_ns
field, for example after changing the power state of a suspended
device.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index 86de6c50fc4181f796c5d0e3d20e796380f112b0..03f4bd069ca88f5a7d1c999425b1738b5e18fed2 100644 (file)
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -47,21 +47,29 @@ static DEFINE_MUTEX(dev_pm_qos_mtx);
 static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
 
 /**
- * dev_pm_qos_read_value - Get PM QoS constraint for a given device.
+ * __dev_pm_qos_read_value - Get PM QoS constraint for a given device.
+ * @dev: Device to get the PM QoS constraint value for.
+ *
+ * This routine must be called with dev->power.lock held.
+ */
+s32 __dev_pm_qos_read_value(struct device *dev)
+{
+       struct pm_qos_constraints *c = dev->power.constraints;
+
+       return c ? pm_qos_read_value(c) : 0;
+}
+
+/**
+ * dev_pm_qos_read_value - Get PM QoS constraint for a given device (locked).
  * @dev: Device to get the PM QoS constraint value for.
  */
 s32 dev_pm_qos_read_value(struct device *dev)
 {
-       struct pm_qos_constraints *c;
        unsigned long flags;
-       s32 ret = 0;
+       s32 ret;
 
        spin_lock_irqsave(&dev->power.lock, flags);
-
-       c = dev->power.constraints;
-       if (c)
-               ret = pm_qos_read_value(c);
-
+       ret = __dev_pm_qos_read_value(dev);
        spin_unlock_irqrestore(&dev->power.lock, flags);
 
        return ret;

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 8c78443bca8f743caa1638f70f46a528d92f19e0..1900ece1cc8ce3c5281f6102ced6e844ddff5932 100644 (file)
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -279,6 +279,47 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev)
        return retval != -EACCES ? retval : -EIO;
 }
 
+struct rpm_qos_data {
+       ktime_t time_now;
+       s64 constraint_ns;
+};
+
+/**
+ * rpm_update_qos_constraint - Update a given PM QoS constraint data.
+ * @dev: Device whose timing data to use.
+ * @data: PM QoS constraint data to update.
+ *
+ * Use the suspend timing data of @dev to update PM QoS constraint data pointed
+ * to by @data.
+ */
+static int rpm_update_qos_constraint(struct device *dev, void *data)
+{
+       struct rpm_qos_data *qos = data;
+       unsigned long flags;
+       s64 delta_ns;
+       int ret = 0;
+
+       spin_lock_irqsave_nested(&dev->power.lock, flags, SINGLE_DEPTH_NESTING);
+
+       if (dev->power.max_time_suspended_ns < 0)
+               goto out;
+
+       delta_ns = dev->power.max_time_suspended_ns -
+               ktime_to_ns(ktime_sub(qos->time_now, dev->power.suspend_time));
+       if (delta_ns <= 0) {
+               ret = -EBUSY;
+               goto out;
+       }
+
+       if (qos->constraint_ns > delta_ns || qos->constraint_ns == 0)
+               qos->constraint_ns = delta_ns;
+
+ out:
+       spin_unlock_irqrestore(&dev->power.lock, flags);
+
+       return ret;
+}
+
 /**
  * rpm_suspend - Carry out runtime suspend of given device.
  * @dev: Device to suspend.
@@ -305,6 +346,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
 {
        int (*callback)(struct device *);
        struct device *parent = NULL;
+       struct rpm_qos_data qos;
        int retval;
 
        trace_rpm_suspend(dev, rpmflags);
@@ -400,6 +442,25 @@ static int rpm_suspend(struct device *dev, int rpmflags)
                goto out;
        }
 
+       qos.constraint_ns = __dev_pm_qos_read_value(dev);
+       if (qos.constraint_ns < 0) {
+               /* Negative constraint means "never suspend". */
+               retval = -EPERM;
+               goto out;
+       }
+       qos.constraint_ns *= NSEC_PER_USEC;
+       qos.time_now = ktime_get();
+
+       if (!dev->power.ignore_children) {
+               retval = device_for_each_child(dev, &qos,
+                                              rpm_update_qos_constraint);
+               if (retval)
+                       goto out;
+       }
+
+       dev->power.suspend_time = qos.time_now;
+       dev->power.max_time_suspended_ns = qos.constraint_ns ? : -1;
+
        __update_runtime_status(dev, RPM_SUSPENDING);
 
        if (dev->pm_domain)
@@ -416,6 +477,8 @@ static int rpm_suspend(struct device *dev, int rpmflags)
        retval = rpm_callback(callback, dev);
        if (retval) {
                __update_runtime_status(dev, RPM_ACTIVE);
+               dev->power.suspend_time = ktime_set(0, 0);
+               dev->power.max_time_suspended_ns = -1;
                dev->power.deferred_resume = false;
                if (retval == -EAGAIN || retval == -EBUSY) {
                        dev->power.runtime_error = 0;
@@ -620,6 +683,9 @@ static int rpm_resume(struct device *dev, int rpmflags)
        if (dev->power.no_callbacks)
                goto no_callback;       /* Assume success. */
 
+       dev->power.suspend_time = ktime_set(0, 0);
+       dev->power.max_time_suspended_ns = -1;
+
        __update_runtime_status(dev, RPM_RESUMING);
 
        if (dev->pm_domain)
@@ -1279,6 +1345,9 @@ void pm_runtime_init(struct device *dev)
        setup_timer(&dev->power.suspend_timer, pm_suspend_timer_fn,
                        (unsigned long)dev);
 
+       dev->power.suspend_time = ktime_set(0, 0);
+       dev->power.max_time_suspended_ns = -1;
+
        init_waitqueue_head(&dev->power.wait_queue);
 }
 
@@ -1296,3 +1365,28 @@ void pm_runtime_remove(struct device *dev)
        if (dev->power.irq_safe && dev->parent)
                pm_runtime_put_sync(dev->parent);
 }
+
+/**
+ * pm_runtime_update_max_time_suspended - Update device's suspend time data.
+ * @dev: Device to handle.
+ * @delta_ns: Value to subtract from the device's max_time_suspended_ns field.
+ *
+ * Update the device's power.max_time_suspended_ns field by subtracting
+ * @delta_ns from it.  The resulting value of power.max_time_suspended_ns is
+ * never negative.
+ */
+void pm_runtime_update_max_time_suspended(struct device *dev, s64 delta_ns)
+{
+       unsigned long flags;
+
+       spin_lock_irqsave(&dev->power.lock, flags);
+
+       if (delta_ns > 0 && dev->power.max_time_suspended_ns > 0) {
+               if (dev->power.max_time_suspended_ns > delta_ns)
+                       dev->power.max_time_suspended_ns -= delta_ns;
+               else
+                       dev->power.max_time_suspended_ns = 0;
+       }
+
+       spin_unlock_irqrestore(&dev->power.lock, flags);
+}

diff --git a/include/linux/pm.h b/include/linux/pm.h
index 3f3ed83a9aa52cf69df6fd7a925d521cbca96f6d..a7676efa68313c175dcce3ffe2b57abb446d68bd 100644 (file)
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -521,6 +521,8 @@ struct dev_pm_info {
        unsigned long           active_jiffies;
        unsigned long           suspended_jiffies;
        unsigned long           accounting_timestamp;
+       ktime_t                 suspend_time;
+       s64                     max_time_suspended_ns;
 #endif
        struct pm_subsys_data   *subsys_data;  /* Owned by the subsystem. */
        struct pm_qos_constraints *constraints;

diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 83b0ea302a8077a84c0eff688ff3322202a266f2..775a3236343d5a4c47717c086ffae02e9d6946b8 100644 (file)
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -78,6 +78,7 @@ int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
 int pm_qos_request_active(struct pm_qos_request *req);
 s32 pm_qos_read_value(struct pm_qos_constraints *c);
 
+s32 __dev_pm_qos_read_value(struct device *dev);
 s32 dev_pm_qos_read_value(struct device *dev);
 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
                           s32 value);
@@ -119,6 +120,8 @@ static inline int pm_qos_request_active(struct pm_qos_request *req)
 static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
                        { return 0; }
 
+static inline s32 __dev_pm_qos_read_value(struct device *dev)
+                       { return 0; }
 static inline s32 dev_pm_qos_read_value(struct device *dev)
                        { return 0; }
 static inline int dev_pm_qos_add_request(struct device *dev,

diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index d3085e72a0ee9b43bbd024bf33b93939e1535d42..609daae7a01450b006a3bbaf490b58af06de58c2 100644 (file)
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -45,6 +45,8 @@ extern void pm_runtime_irq_safe(struct device *dev);
 extern void __pm_runtime_use_autosuspend(struct device *dev, bool use);
 extern void pm_runtime_set_autosuspend_delay(struct device *dev, int delay);
 extern unsigned long pm_runtime_autosuspend_expiration(struct device *dev);
+extern void pm_runtime_update_max_time_suspended(struct device *dev,
+                                                s64 delta_ns);
 
 static inline bool pm_children_suspended(struct device *dev)
 {
@@ -148,6 +150,9 @@ static inline void pm_runtime_set_autosuspend_delay(struct device *dev,
 static inline unsigned long pm_runtime_autosuspend_expiration(
                                struct device *dev) { return 0; }
 
+static inline void pm_runtime_update_max_time_suspended(struct device *dev,
+                                                       s64 delta_ns) {}
+
 #endif /* !CONFIG_PM_RUNTIME */
 
 static inline int pm_runtime_idle(struct device *dev)