PM: Measure device suspend and resume times

Measure and print the time of suspending and resuming all devices.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/base/power/main.c

@@ -372,6 +372,23 @@ static void pm_dev_err(struct device *dev, pm_message_t state, char *info,
 		kobject_name(&dev->kobj), pm_verb(state.event), info, error);
 }
 
+static void dpm_show_time(ktime_t starttime, pm_message_t state, char *info)
+{
+	ktime_t calltime;
+	s64 usecs64;
+	int usecs;
+
+	calltime = ktime_get();
+	usecs64 = ktime_to_ns(ktime_sub(calltime, starttime));
+	do_div(usecs64, NSEC_PER_USEC);
+	usecs = usecs64;
+	if (usecs == 0)
+		usecs = 1;
+	pr_info("PM: %s%s%s of devices complete after %ld.%03ld msecs\n",
+		info ?: "", info ? " " : "", pm_verb(state.event),
+		usecs / USEC_PER_MSEC, usecs % USEC_PER_MSEC);
+}
+
 /*------------------------- Resume routines -------------------------*/
 
 /**
@@ -408,6 +425,7 @@ static int device_resume_noirq(struct device *dev, pm_message_t state)
 void dpm_resume_noirq(pm_message_t state)
 {
 	struct device *dev;
+	ktime_t starttime = ktime_get();
 
 	mutex_lock(&dpm_list_mtx);
 	transition_started = false;
@@ -421,6 +439,7 @@ void dpm_resume_noirq(pm_message_t state)
 				pm_dev_err(dev, state, " early", error);
 		}
 	mutex_unlock(&dpm_list_mtx);
+	dpm_show_time(starttime, state, "early");
 	resume_device_irqs();
 }
 EXPORT_SYMBOL_GPL(dpm_resume_noirq);
@@ -506,6 +525,7 @@ static int device_resume(struct device *dev, pm_message_t state)
 static void dpm_resume(pm_message_t state)
 {
 	struct list_head list;
+	ktime_t starttime = ktime_get();
 
 	INIT_LIST_HEAD(&list);
 	mutex_lock(&dpm_list_mtx);
@@ -534,6 +554,7 @@ static void dpm_resume(pm_message_t state)
 	}
 	list_splice(&list, &dpm_list);
 	mutex_unlock(&dpm_list_mtx);
+	dpm_show_time(starttime, state, NULL);
 }
 
 /**
@@ -666,6 +687,7 @@ static int device_suspend_noirq(struct device *dev, pm_message_t state)
 int dpm_suspend_noirq(pm_message_t state)
 {
 	struct device *dev;
+	ktime_t starttime = ktime_get();
 	int error = 0;
 
 	suspend_device_irqs();
@@ -681,6 +703,8 @@ int dpm_suspend_noirq(pm_message_t state)
 	mutex_unlock(&dpm_list_mtx);
 	if (error)
 		dpm_resume_noirq(resume_event(state));
+	else
+		dpm_show_time(starttime, state, "late");
 	return error;
 }
 EXPORT_SYMBOL_GPL(dpm_suspend_noirq);
@@ -760,6 +784,7 @@ static int device_suspend(struct device *dev, pm_message_t state)
 static int dpm_suspend(pm_message_t state)
 {
 	struct list_head list;
+	ktime_t starttime = ktime_get();
 	int error = 0;
 
 	INIT_LIST_HEAD(&list);
@@ -785,6 +810,8 @@ static int dpm_suspend(pm_message_t state)
 	}
 	list_splice(&list, dpm_list.prev);
 	mutex_unlock(&dpm_list_mtx);
+	if (!error)
+		dpm_show_time(starttime, state, NULL);
 	return error;
 }