linux-kernel - [PATCH v2] PM / sleep: add configurable delay for pm

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Message-Id: <20250507034449.336863-1-zhangzihuan@kylinos.cn>
Date: Wed,  7 May 2025 11:44:49 +0800
From: Zihuan Zhang <zhangzihuan@...inos.cn>
To: corbet@....net,
	rafael@...nel.org,
	len.brown@...el.com,
	pavel@...nel.org,
	akpm@...ux-foundation.org,
	paulmck@...nel.org,
	rostedt@...dmis.org,
	thuth@...hat.com,
	bp@...en8.de,
	ardb@...nel.org,
	gregkh@...uxfoundation.org
Cc: linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org,
	Zihuan Zhang <zhangzihuan@...inos.cn>
Subject: [PATCH v2] PM / sleep: add configurable delay for pm_test

This patch turns this 5 second delay into a configurable module
parameter, so users can determine how long to wait in this
pseudo-hibernate state before resuming the system.

The configurable delay parameter has been added to suspend and
synchronized to hibernation.

Example (wait 30 seconds);

  # echo 30 > /sys/module/hibernate/parameters/pm_test_delay
  # echo core > /sys/power/pm_test

Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
---
v2:
 - Fix typos.
---
 Documentation/admin-guide/kernel-parameters.txt | 7 +++++++
 kernel/power/hibernate.c                        | 9 +++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index d9fd26b95b34..1532c6fdc2d1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6998,6 +6998,13 @@
 			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
 			is set. Default value is 5.
 
+	hibernate.pm_test_delay=
+			[hibernate]
+			Sets the number of seconds to remain in a hibernation test
+			mode before resuming the system (see
+			/sys/power/pm_test). Only available when CONFIG_PM_DEBUG
+			is set. Default value is 5.
+
 	svm=		[PPC]
 			Format: { on | off | y | n | 1 | 0 }
 			This parameter controls use of the Protected
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 23c0f4e6cb2f..485133af884d 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -133,10 +133,15 @@ bool system_entering_hibernation(void)
 EXPORT_SYMBOL(system_entering_hibernation);
 
 #ifdef CONFIG_PM_DEBUG
+static unsigned int pm_test_delay = 5;
+module_param(pm_test_delay, uint, 0644);
+MODULE_PARM_DESC(pm_test_delay,
+		 "Number of seconds to wait before resuming from hibernation test");
 static void hibernation_debug_sleep(void)
 {
-	pr_info("debug: Waiting for 5 seconds.\n");
-	mdelay(5000);
+	pr_info("hibernation debug: Waiting for %d second(s).\n",
+		pm_test_delay);
+	mdelay(pm_test_delay * 1000);
 }
 
 static int hibernation_test(int level)
-- 
2.25.1