linux-kernel - [PATCH 1/5] PM: wakeup: Add out-of-band system wakeup support for devices

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Message-Id: <20250922-pm-v4-v1-1-7ed2e98065ad@nxp.com>
Date: Mon, 22 Sep 2025 10:14:09 +0800
From: Peng Fan <peng.fan@....com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>, 
 Pavel Machek <pavel@...nel.org>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Danilo Krummrich <dakr@...nel.org>, Ulf Hansson <ulf.hansson@...aro.org>, 
 Peter Chen <peter.chen@...nel.org>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, 
 Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-usb@...r.kernel.org, imx@...ts.linux.dev, 
 linux-arm-kernel@...ts.infradead.org, Peng Fan <peng.fan@....com>
Subject: [PATCH 1/5] PM: wakeup: Add out-of-band system wakeup support for
 devices

Some devices can wake up the system from suspend even when their power
domains are turned off. This is possible because their system-wakeup logic
resides in an always-on power domain - indicating that they support
out-of-band system wakeup.

Currently, PM domain core doesn't power off such devices if they are marked
as system wakeup sources. To better represent devices with out-of-band
wakeup capability, this patch introduces a new flag out_band_wakeup in
'struct dev_pm_info'.

Two helper APIs are added:
 - device_set_out_band_wakeup() - to mark a device as having out-of-band
   wakeup capability.
 - device_out_band_wakeup() - to query the flag.

Allow the PM core and drivers to distinguish between regular and
out-of-band wakeup sources, enable more accurate power management decision.

Signed-off-by: Peng Fan <peng.fan@....com>
---
 drivers/base/power/main.c |  1 +
 include/linux/pm.h        |  1 +
 include/linux/pm_wakeup.h | 17 +++++++++++++++++
 3 files changed, 19 insertions(+)

diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index b9a34c3425ecfab038097e2c03645157af2e598c..6b1ca729dc3e34292952c9c309aab3f34a0a664a 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -2124,6 +2124,7 @@ static int device_prepare(struct device *dev, pm_message_t state)
 	device_lock(dev);

 	dev->power.wakeup_path = false;
+	dev->power.out_band_wakeup = false;

 	if (dev->power.no_pm_callbacks)
 		goto unlock;
diff --git a/include/linux/pm.h b/include/linux/pm.h
index cc7b2dc28574c24ece2f651352d4d23ecaf15f31..5b28a4f2e87e2aa34acc709e146ce729acace344 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -684,6 +684,7 @@ struct dev_pm_info {
 	bool			smart_suspend:1;	/* Owned by the PM core */
 	bool			must_resume:1;		/* Owned by the PM core */
 	bool			may_skip_resume:1;	/* Set by subsystems */
+	bool			out_band_wakeup:1;
 	bool			strict_midlayer:1;
 #else
 	bool			should_wakeup:1;
diff --git a/include/linux/pm_wakeup.h b/include/linux/pm_wakeup.h
index c838b4a30f876ef5a66972d16f461cfba9ff2814..41e8f344a20563898e827da62dd240b8cbe657d2 100644
--- a/include/linux/pm_wakeup.h
+++ b/include/linux/pm_wakeup.h
@@ -94,6 +94,16 @@ static inline void device_set_wakeup_path(struct device *dev)
 	dev->power.wakeup_path = true;
 }

+static inline void device_set_out_band_wakeup(struct device *dev)
+{
+	dev->power.out_band_wakeup = true;
+}
+
+static inline bool device_out_band_wakeup(struct device *dev)
+{
+	return dev->power.out_band_wakeup;
+}
+
 /* drivers/base/power/wakeup.c */
 extern struct wakeup_source *wakeup_source_register(struct device *dev,
 						    const char *name);
@@ -162,6 +172,13 @@ static inline bool device_wakeup_path(struct device *dev)

 static inline void device_set_wakeup_path(struct device *dev) {}

+static inline void device_set_out_band_wakeup(struct device *dev) {}
+
+static inline bool device_out_band_wakeup(struct device *dev)
+{
+	return false;
+}
+
 static inline void __pm_stay_awake(struct wakeup_source *ws) {}

 static inline void pm_stay_awake(struct device *dev) {}

-- 
2.37.1