PM / sleep: Do not print debug messages by default

Debug messages from the system suspend/hibernation infrastructure can
fill up the entire kernel log buffer in some cases and anyway they
are only useful for debugging.  They depend on CONFIG_PM_DEBUG, but
that is set as a rule as some generally useful diagnostic facilities
depend on it too.

For this reason, avoid printing those messages by default, but make
it possible to turn them on as needed with the help of a new sysfs
attribute under /sys/power/.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/base/power/main.c

@@ -418,7 +418,6 @@ static void pm_dev_err(struct device *dev, pm_message_t state, const char *info,
 		dev_name(dev), pm_verb(state.event), info, error);
 }
 
-#ifdef CONFIG_PM_DEBUG
 static void dpm_show_time(ktime_t starttime, pm_message_t state,
 			  const char *info)
 {
@@ -432,14 +431,11 @@ static void dpm_show_time(ktime_t starttime, pm_message_t state,
 	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);
+
+	pm_pr_dbg("%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);
 }
-#else
-static inline void dpm_show_time(ktime_t starttime, pm_message_t state,
-				 const char *info) {}
-#endif /* CONFIG_PM_DEBUG */
 
 static int dpm_run_callback(pm_callback_t cb, struct device *dev,
 			    pm_message_t state, const char *info)