linux-kernel - [PATCH v1 06/10] PM: sleep: Adjust check before setting power.must

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Message-ID: <3548152.QJadu78ljV@rjwysocki.net>
Date: Tue, 11 Feb 2025 22:10:39 +0100
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Linux PM <linux-pm@...r.kernel.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
 Alan Stern <stern@...land.harvard.edu>, Ulf Hansson <ulf.hansson@...aro.org>,
 Johan Hovold <johan@...nel.org>,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Jon Hunter <jonathanh@...dia.com>
Subject:
 [PATCH v1 06/10] PM: sleep: Adjust check before setting power.must_resume

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

Use pm_runtime_need_not_resume() in the check deciding whether or not
the device's power.must_resume flag needs to be set, so it covers the
device's active children counter in addition to its runtime PM usage
counter, rearrange that check and adjust the comment next to it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
---
 drivers/base/power/main.c    |   12 +++++-------
 drivers/base/power/runtime.c |    2 +-
 include/linux/pm_runtime.h   |    2 ++
 3 files changed, 8 insertions(+), 8 deletions(-)

--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -1268,14 +1268,12 @@
 	dev->power.is_noirq_suspended = true;
 
 	/*
-	 * Skipping the resume of devices that were in use right before the
-	 * system suspend (as indicated by their PM-runtime usage counters)
-	 * would be suboptimal.  Also resume them if doing that is not allowed
-	 * to be skipped.
+	 * If it is not allowed to skip the resume of the device or it was in
+	 * use before the system suspend has started (in which case it needs to
+	 * be resumed for consistency), set the "must resume" flag for it.
 	 */
-	if (atomic_read(&dev->power.usage_count) > 1 ||
-	    !(dev_pm_test_driver_flags(dev, DPM_FLAG_MAY_SKIP_RESUME) &&
-	      dev->power.may_skip_resume))
+	if (!(dev_pm_test_driver_flags(dev, DPM_FLAG_MAY_SKIP_RESUME) &&
+	      dev->power.may_skip_resume) || !pm_runtime_need_not_resume(dev))
 		dev->power.must_resume = true;
 
 	if (dev->power.must_resume) {
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -1874,7 +1874,7 @@
 	pm_request_idle(link->supplier);
 }
 
-static bool pm_runtime_need_not_resume(struct device *dev)
+bool pm_runtime_need_not_resume(struct device *dev)
 {
 	return atomic_read(&dev->power.usage_count) <= 1 &&
 		(atomic_read(&dev->power.child_count) == 0 ||
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -66,6 +66,7 @@
 
 extern int pm_generic_runtime_suspend(struct device *dev);
 extern int pm_generic_runtime_resume(struct device *dev);
+extern bool pm_runtime_need_not_resume(struct device *dev);
 extern int pm_runtime_force_suspend(struct device *dev);
 extern int pm_runtime_force_resume(struct device *dev);
 
@@ -254,6 +255,7 @@
 
 static inline int pm_generic_runtime_suspend(struct device *dev) { return 0; }
 static inline int pm_generic_runtime_resume(struct device *dev) { return 0; }
+static inline bool pm_runtime_need_not_resume(struct device *dev) {return true; }
 static inline int pm_runtime_force_suspend(struct device *dev) { return 0; }
 static inline int pm_runtime_force_resume(struct device *dev) { return 0; }