linux-kernel - [PATCH v1 2/2] driver core/PM: Set power.no_callbacks along with power.no

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Message-ID: <1950054.tdWV9SEqCh@rafael.j.wysocki>
Date: Thu, 28 Aug 2025 12:59:24 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 LKML <linux-kernel@...r.kernel.org>, Sudeep Holla <sudeep.holla@....com>,
 Danilo Krummrich <dakr@...nel.org>
Subject:
 [PATCH v1 2/2] driver core/PM: Set power.no_callbacks along with power.no_pm

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Devices with power.no_pm set are not expected to need any power
management at all, so modify device_set_pm_not_required() to set
power.no_callbacks for them too in case runtime PM will be enabled
for any of them (which in principle may be done for convenience if
such a device participates in a dependency chain).

Since device_set_pm_not_required() must be called before device_add()
or it would not have any effect, it can update power.no_callbacks
without locking, unlike pm_runtime_no_callbacks() that can be called
after registering the target device.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 include/linux/device.h |    3 +++
 1 file changed, 3 insertions(+)

--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -851,6 +851,9 @@
 static inline void device_set_pm_not_required(struct device *dev)
 {
 	dev->power.no_pm = true;
+#ifdef CONFIG_PM
+	dev->power.no_callbacks = true;
+#endif
 }

 static inline void dev_pm_syscore_device(struct device *dev, bool val)