[PATCH] PM / sleep: Add pm_debug_messages boot command control

From: Chen Yu
Date: Fri Mar 27 2020 - 07:13:31 EST


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@xxxxxxxxxxxxx>
Cc: Len Brown <lenb@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
---
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