linux-kernel - [PATCH] PM / sleep: Add pm_debug

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Date:   Fri, 27 Mar 2020 19:11:41 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     linux-pm@...r.kernel.org
Cc:     Pavel Machek <pavel@....cz>, linux-kernel@...r.kernel.org,
        Chen Yu <yu.c.chen@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH] PM / sleep: Add pm_debug_messages boot command control

Debug messages from the system suspend/hibernation infrastructure
is disabled by default, and can only be enabled after the system
has boot up via /sys/power/pm_debug_messages. This makes the hibernation
resume hard to track as it involves system boot up across hibernation.
There's no chance for software_resume() to track the resume process,
eg.

Turning on the pm_debug_messages during boot up by appending
'pm_debug_message'.

Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc: Len Brown <lenb@...nel.org>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Chen Yu <yu.c.chen@...el.com>
---
 kernel/power/main.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 69b7a8aeca3b..1da3d7c15e03 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -535,6 +535,13 @@ static ssize_t pm_debug_messages_store(struct kobject *kobj,
 
 power_attr(pm_debug_messages);
 
+static int __init pm_debug_message_setup(char *str)
+{
+	pm_debug_messages_on = true;
+	return 1;
+}
+__setup("pm_debug_message", pm_debug_message_setup);
+
 /**
  * __pm_pr_dbg - Print a suspend debug message to the kernel log.
  * @defer: Whether or not to use printk_deferred() to print the message.
-- 
2.17.1