From 45557aff35b679bf2ed282cbc62339d31192dc24 Mon Sep 17 00:00:00 2001
From: Sameer Nanda <snanda@chromium.org>
Date: Wed, 6 Jun 2012 11:03:57 -0700
Subject: [PATCH] CHROMIUM: power: add knob for printing device resume times

Added a new knob called /sys/power/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).

This patch has been sent upstream but seems to be in limbo there.  Pushing
as a CHROMIUM patch for now and will revisit once the upstream discussion
happens.

BUG=chromium-os:30539
TEST=First enable device suspend/resume time printing by issuing this
command: "echo 1 > /sys/power/pm_print_times".  Then do a suspend/resume
cycle.  After resuming look at dmesg and there should be several "call
<device> returned 0 after <time> usecs".  The <time> in these messages
indicates the time taken by the <device> to suspend or resume.

Change-Id: I8f210acd6667a870d286bff412df6b8014438e8c
Signed-off-by: Sameer Nanda <snanda@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/24628
Reviewed-by: Olof Johansson <olofj@chromium.org>
---
 Documentation/ABI/testing/sysfs-power | 13 ++++++++++
 drivers/base/power/main.c             |  4 ++--
 drivers/base/power/power.h            | 11 +++++++++
 kernel/power/main.c                   | 34 +++++++++++++++++++++++++++
 4 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index b464d12761ba..79210d1d9a83 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -172,3 +172,16 @@ Description:
 
 		Reading from this file will display the current value, which is
 		set to 1 MB by default.
+
+What:		/sys/power/pm_print_times
+Date:		May 2012
+Contact:	Sameer Nanda <snanda@chromium.org>
+Description:
+		The /sys/power/pm_print_times file allows user space to
+		control whether the time taken by devices to suspend and
+		resume is printed.  These prints are useful for hunting down
+		devices that take too long to suspend or resume.
+
+		Writing a "1" enables this printing while writing a "0"
+		disables it.  The default value is "0".  Reading from this file
+		will display the current value.
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index b462c0e341cb..ca8b2b5c4add 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 eeb4bff9505c..12c77b7ff8e8 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 1c12581f1c62..97eea046d1a8 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.  0 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,
-- 
2.20.1