linux-kernel - [PATCH v1 0/9] PM: Check power.needs_force_resume in pm_runtime_force

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Message-ID: <3306233.5fSG56mABF@rjwysocki.net>
Date: Wed, 25 Jun 2025 21:17:34 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Linux ACPI <linux-acpi@...r.kernel.org>,
 Linux PCI <linux-pci@...r.kernel.org>, Ulf Hansson <ulf.hansson@...aro.org>,
 Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject:
 [PATCH v1 0/9] PM: Check power.needs_force_resume in
 pm_runtime_force_suspend()

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

Add a power.needs_force_resume check to pm_runtime_force_suspend() so
it need not rely on the runtime PM status of the device when deciding
whether or not to return early.

With the new check in place, pm_runtime_force_suspend() will also skip
devices with the runtime PM status equal to RPM_ACTIVE if they have
power.needs_force_resume set, so it won't need to change the RPM
status of the device to RPM_SUSPENDED in addition to setting
power.needs_force_resume in the case when pm_runtime_need_not_resume()
return false.

This allows the runtime PM status update to be removed from
pm_runtime_force_resume(), so the runtime PM status remains unchanged
between the pm_runtime_force_suspend() and pm_runtime_force_resume()
calls.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/base/power/runtime.c |   21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1975,7 +1975,7 @@
 	int ret;

 	pm_runtime_disable(dev);
-	if (pm_runtime_status_suspended(dev))
+	if (pm_runtime_status_suspended(dev) || dev->power.needs_force_resume)
 		return 0;

 	callback = RPM_GET_CALLBACK(dev, runtime_suspend);
@@ -1990,15 +1990,16 @@
 	/*
 	 * If the device can stay in suspend after the system-wide transition
 	 * to the working state that will follow, drop the children counter of
-	 * its parent, but set its status to RPM_SUSPENDED anyway in case this
-	 * function will be called again for it in the meantime.
+	 * its parent and the usage counters of its suppliers.  Otherwise, set
+	 * power.needs_force_resume to let pm_runtime_force_resume() know that
+	 * the device needs to be taken care of and to prevent this function
+	 * from handling the device again in case the device is passed to it
+	 * once more subsequently.
 	 */
-	if (pm_runtime_need_not_resume(dev)) {
+	if (pm_runtime_need_not_resume(dev))
 		pm_runtime_set_suspended(dev);
-	} else {
-		__update_runtime_status(dev, RPM_SUSPENDED);
+	else
 		dev->power.needs_force_resume = true;
-	}

 	return 0;

@@ -2029,12 +2030,6 @@
 	if (!dev->power.needs_force_resume)
 		goto out;

-	/*
-	 * The value of the parent's children counter is correct already, so
-	 * just update the status of the device.
-	 */
-	__update_runtime_status(dev, RPM_ACTIVE);
-
 	callback = RPM_GET_CALLBACK(dev, runtime_resume);

 	dev_pm_disable_wake_irq_check(dev, false);