linux-kernel - [PATCH] power: add knob for printing device resume times

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Date:	Tue, 22 May 2012 12:16:45 -0700
From:	Sameer Nanda <snanda@...omium.org>
To:	len.brown@...el.com, pavel@....cz, rjw@...k.pl,
	gregkh@...uxfoundation.org
Cc:	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Sameer Nanda <snanda@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: [PATCH] power: add knob for printing device resume times

Added a new knob called /sys/powe/pm_print_times. Setting it to 1
enables printing of time taken by devices to suspend and resume.
Setting it to 0 disables this printing (unless overridden by
initcall_debug kernel command line option).

Signed-off-by: Sameer Nanda <snanda@...omium.org>
cc: Greg KH <gregkh@...uxfoundation.org>
cc: Rafael J. Wysocki <rjw@...k.pl>
cc: Steven Rostedt <rostedt@...dmis.org>
---
 drivers/base/power/main.c  |    4 ++--
 drivers/base/power/power.h |   11 +++++++++++
 kernel/power/main.c        |   34 ++++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index b462c0e..ca8b2b5 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -166,7 +166,7 @@ static ktime_t initcall_debug_start(struct device *dev)
 {
 	ktime_t calltime = ktime_set(0, 0);
 
-	if (initcall_debug) {
+	if (pm_print_times) {
 		pr_info("calling  %s+ @ %i, parent: %s\n",
 			dev_name(dev), task_pid_nr(current),
 			dev->parent ? dev_name(dev->parent) : "none");
@@ -181,7 +181,7 @@ static void initcall_debug_report(struct device *dev, ktime_t calltime,
 {
 	ktime_t delta, rettime;
 
-	if (initcall_debug) {
+	if (pm_print_times) {
 		rettime = ktime_get();
 		delta = ktime_sub(rettime, calltime);
 		pr_info("call %s+ returned %d after %Ld usecs\n", dev_name(dev),
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index eeb4bff..12c77b7 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -85,3 +85,14 @@ static inline int pm_qos_sysfs_add(struct device *dev) { return 0; }
 static inline void pm_qos_sysfs_remove(struct device *dev) {}
 
 #endif
+
+#ifdef CONFIG_PM_DEBUG
+
+extern int pm_print_times_enabled;
+#define pm_print_times (initcall_debug || pm_print_times_enabled)
+
+#else /* CONFIG_PM_DEBUG */
+
+#define pm_print_times initcall_debug
+
+#endif /* CONFIG_PM_DEBUG */
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 1c12581..602f617 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -132,6 +132,39 @@ static ssize_t pm_test_store(struct kobject *kobj, struct kobj_attribute *attr,
 }
 
 power_attr(pm_test);
+
+/*
+ *	pm_print_times: print time taken by devices to suspend and resume.
+ *
+ *	show() returns whether printing of suspend and resume times is enabled.
+ *
+ *	store() accepts 0 or 1.  O disables printing and 1 enables it.
+ */
+int pm_print_times_enabled;
+
+static ssize_t pm_print_times_show(struct kobject *kobj,
+				   struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", pm_print_times_enabled);
+}
+
+static ssize_t pm_print_times_store(struct kobject *kobj,
+				    struct kobj_attribute *attr,
+				    const char *buf, size_t n)
+{
+	unsigned long val;
+
+	if (kstrtoul(buf, 10, &val))
+		return -EINVAL;
+
+	if (val > 1)
+		return -EINVAL;
+
+	pm_print_times_enabled = val;
+	return n;
+}
+
+power_attr(pm_print_times);
 #endif /* CONFIG_PM_DEBUG */
 
 #ifdef CONFIG_DEBUG_FS
@@ -411,6 +444,7 @@ static struct attribute * g[] = {
 	&wakeup_count_attr.attr,
 #ifdef CONFIG_PM_DEBUG
 	&pm_test_attr.attr,
+	&pm_print_times_attr.attr,
 #endif
 #endif
 	NULL,
-- 
1.7.7.3

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