[PATCH v2] PM: add statistics debugfs file for suspend to ram

[Liu, ShuoX]

From: ShuoX Liu <shuox.liu@xxxxxxxxx>

Record S3 failure time about each reason and the latest two failed
devices' names in S3 progress.
We can check it through 'suspend_stats' entry in debugfs.

The motivation of the patch:

We are enabling power features on Medfield. Comparing with PC/notebook,
a mobile enters/exits suspend-2-ram (we call it s3 on Medfield) far
more frequently. If it can't enter suspend-2-ram in time, the power
might be used up soon.

We often find sometimes, a device suspend fails. Then, system retries
s3 over and over again. As display is off, testers and developers
don't know what happens.

Some testers and developers complain they don't know if system
tries suspend-2-ram, and what device fails to suspend. They need
such info for a quick check. The patch adds suspend_stats under
debugfs for users to check suspend to RAM statistics quickly.

If not using this patch, we have other methods to get info about
what device fails. One is to turn on  CONFIG_PM_DEBUG, but users
would get too much info and testers need recompile the system.

In addition, dynamic debug is another good tool to dump debug info.
But it still doesn't match our utilization scenario closely.
1) user need write a user space parser to process the syslog output;
2) Our testing scenario is we leave the mobile for at least hours.
   Then, check its status. No serial console available during the
   testing. One is because console would be suspended, and the other
   is serial console connecting with spi or HSU devices would consume
   power. These devices are powered off at suspend-2-ram.

Thank Greg and Rafael for their great comments.

Change Log:
  V2:
	1) Change the sysfs entry to debugfs.
	2) Add some explanation in document file.

Contribution:
	yanmin_zhang@xxxxxxxxxxxxxxx

Signed-off-by: ShuoX Liu <shuox.liu@xxxxxxxxx>
---
 Documentation/power/basic-pm-debugging.txt |   19 +++++++++
 drivers/base/power/main.c                  |   31 +++++++++++++-
 include/linux/suspend.h                    |   16 +++++++
 kernel/power/main.c                        |   59 ++++++++++++++++++++++++++++
 kernel/power/suspend.c                     |   13 +++++-
 5 files changed, 133 insertions(+), 5 deletions(-)

diff --git a/Documentation/power/basic-pm-debugging.txt b/Documentation/power/basic-pm-debugging.txt
index ddd7817..acbd3e0 100644
--- a/Documentation/power/basic-pm-debugging.txt
+++ b/Documentation/power/basic-pm-debugging.txt
@@ -201,3 +201,22 @@ case, you may be able to search for failing drivers by following the procedure
 analogous to the one described in section 1.  If you find some failing drivers,
 you will have to unload them every time before an STR transition (ie. before
 you run s2ram), and please report the problems with them.
+
+There is a debugfs entry which shows the suspend to RAM statistics. Here is an
+example of its output.
+	# mount -t debugfs none /sys/kernel/debug
+	# cat /sys/kernel/debug/suspend_stats
+	success: 20
+	fail: 5
+	failed_freeze: 0
+	failed_prepare: 0
+	failed_suspend: 5
+	failed_suspend_noirq: 0
+	failed_resume: 0
+	failed_resume_noirq: 0
+	failed_devs:
+	  last_failed: alarm
+		       adc
+Field success means the success number of suspend to RAM, and field fail means
+the failure number. Others are the failure number of different steps of suspend
+to RAM. suspend_stats just lists the last 2 failed devices.
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index a854591..da1c561 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -46,6 +46,7 @@ LIST_HEAD(dpm_prepared_list);
 LIST_HEAD(dpm_suspended_list);
 LIST_HEAD(dpm_noirq_list);
 
+struct suspend_stats suspend_stats;
 static DEFINE_MUTEX(dpm_list_mtx);
 static pm_message_t pm_transition;
 
@@ -180,6 +181,15 @@ static void initcall_debug_report(struct device *dev, ktime_t calltime,
 	}
 }
 
+static void dpm_save_dev_name(const char *name)
+{
+	strlcpy(suspend_stats.failed_devs[suspend_stats.last_failed],
+		name,
+		sizeof(suspend_stats.failed_devs[0]));
+	suspend_stats.last_failed++;
+	suspend_stats.last_failed %= REC_FAILED_DEV_NUM;
+}
+
 /**
  * dpm_wait - Wait for a PM operation to complete.
  * @dev: Device to wait for.
@@ -464,8 +474,11 @@ void dpm_resume_noirq(pm_message_t state)
 		mutex_unlock(&dpm_list_mtx);
 
 		error = device_resume_noirq(dev, state);
-		if (error)
+		if (error) {
+			suspend_stats.failed_resume_noirq++;
+			dpm_save_dev_name(dev_name(dev));
 			pm_dev_err(dev, state, " early", error);
+		}
 
 		mutex_lock(&dpm_list_mtx);
 		put_device(dev);
@@ -626,8 +639,11 @@ void dpm_resume(pm_message_t state)
 			mutex_unlock(&dpm_list_mtx);
 
 			error = device_resume(dev, state, false);
-			if (error)
+			if (error) {
+				suspend_stats.failed_resume++;
+				dpm_save_dev_name(dev_name(dev));
 				pm_dev_err(dev, state, "", error);
+			}
 
 			mutex_lock(&dpm_list_mtx);
 		}
@@ -802,6 +818,8 @@ int dpm_suspend_noirq(pm_message_t state)
 		mutex_lock(&dpm_list_mtx);
 		if (error) {
 			pm_dev_err(dev, state, " late", error);
+			suspend_stats.failed_suspend_noirq++;
+			dpm_save_dev_name(dev_name(dev));
 			put_device(dev);
 			break;
 		}
@@ -923,8 +941,10 @@ static void async_suspend(void *data, async_cookie_t cookie)
 	int error;
 
 	error = __device_suspend(dev, pm_transition, true);
-	if (error)
+	if (error) {
+		dpm_save_dev_name(dev_name(dev));
 		pm_dev_err(dev, pm_transition, " async", error);
+	}
 
 	put_device(dev);
 }
@@ -967,6 +987,7 @@ int dpm_suspend(pm_message_t state)
 		mutex_lock(&dpm_list_mtx);
 		if (error) {
 			pm_dev_err(dev, state, "", error);
+			dpm_save_dev_name(dev_name(dev));
 			put_device(dev);
 			break;
 		}
@@ -982,6 +1003,8 @@ int dpm_suspend(pm_message_t state)
 		error = async_error;
 	if (!error)
 		dpm_show_time(starttime, state, NULL);
+	else
+		suspend_stats.failed_suspend++;
 	return error;
 }
 
@@ -1090,6 +1113,8 @@ int dpm_suspend_start(pm_message_t state)
 	error = dpm_prepare(state);
 	if (!error)
 		error = dpm_suspend(state);
+	else
+		suspend_stats.failed_prepare++;
 	return error;
 }
 EXPORT_SYMBOL_GPL(dpm_suspend_start);
diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 6bbcef2..6a8ff23 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -34,6 +34,22 @@ typedef int __bitwise suspend_state_t;
 #define PM_SUSPEND_MEM		((__force suspend_state_t) 3)
 #define PM_SUSPEND_MAX		((__force suspend_state_t) 4)
 
+struct suspend_stats {
+	int	success;
+	int	fail;
+	int	failed_freeze;
+	int	failed_prepare;
+	int	failed_suspend;
+	int	failed_suspend_noirq;
+	int	failed_resume;
+	int	failed_resume_noirq;
+#define	REC_FAILED_DEV_NUM	2
+	char	failed_devs[REC_FAILED_DEV_NUM][40];
+	int	last_failed;
+};
+
+extern struct suspend_stats suspend_stats;
+
 /**
  * struct platform_suspend_ops - Callbacks for managing platform dependent
  *	system sleep states.
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 6c601f8..0977f5d 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -12,6 +12,8 @@
 #include <linux/string.h>
 #include <linux/resume-trace.h>
 #include <linux/workqueue.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
 
 #include "power.h"
 
@@ -133,6 +135,59 @@ power_attr(pm_test);
 
 #endif /* CONFIG_PM_SLEEP */
 
+#ifdef CONFIG_DEBUG_FS
+static int suspend_stats_show(struct seq_file *s, void *unused)
+{
+	int i, index, last_index;
+
+	last_index = suspend_stats.last_failed + REC_FAILED_DEV_NUM - 1;
+	last_index %= REC_FAILED_DEV_NUM;
+	seq_printf(s, "%s: %d\n%s: %d\n%s: %d\n%s: %d\n"
+			"%s: %d\n%s: %d\n%s: %d\n%s: %d\n",
+			"success", suspend_stats.success,
+			"fail", suspend_stats.fail,
+			"failed_freeze", suspend_stats.failed_freeze,
+			"failed_prepare", suspend_stats.failed_prepare,
+			"failed_suspend", suspend_stats.failed_suspend,
+			"failed_suspend_noirq",
+				suspend_stats.failed_suspend_noirq,
+			"failed_resume", suspend_stats.failed_resume,
+			"failed_resume_noirq",
+				suspend_stats.failed_resume_noirq);
+	seq_printf(s,	"failed_devs:\n  last_failed:\t%s\n",
+			suspend_stats.failed_devs[last_index]);
+	for (i = 1; i < REC_FAILED_DEV_NUM; i++) {
+		index = last_index + REC_FAILED_DEV_NUM - i;
+		index %= REC_FAILED_DEV_NUM;
+		seq_printf(s, "\t\t%s\n",
+			suspend_stats.failed_devs[index]);
+	}
+
+	return 0;
+}
+
+static int suspend_stats_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, suspend_stats_show, NULL);
+}
+
+static const struct file_operations suspend_stats_operations = {
+	.open           = suspend_stats_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = single_release,
+};
+
+static int __init pm_debugfs_init(void)
+{
+	debugfs_create_file("suspend_stats", S_IFREG | S_IRUGO,
+			NULL, NULL, &suspend_stats_operations);
+	return 0;
+}
+
+late_initcall(pm_debugfs_init);
+#endif /* CONFIG_DEBUG_FS */
+
 struct kobject *power_kobj;
 
 /**
@@ -194,6 +249,10 @@ static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 	}
 	if (state < PM_SUSPEND_MAX && *s)
 		error = enter_state(state);
+		if (error)
+			suspend_stats.fail++;
+		else
+			suspend_stats.success++;
 #endif
 
  Exit:
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index b6b71ad..9bb4281 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -106,6 +106,8 @@ static int suspend_prepare(void)
 	error = suspend_freeze_processes();
 	if (!error)
 		return 0;
+	else
+		suspend_stats.failed_freeze++;
 
 	suspend_thaw_processes();
 	usermodehelper_enable();
@@ -315,8 +317,15 @@ int enter_state(suspend_state_t state)
  */
 int pm_suspend(suspend_state_t state)
 {
-	if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
-		return enter_state(state);
+	int ret;
+	if (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX) {
+		ret = enter_state(state);
+		if (ret)
+			suspend_stats.fail++;
+		else
+			suspend_stats.success++;
+		return ret;
+	}
 	return -EINVAL;
 }
 EXPORT_SYMBOL(pm_suspend);

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