[PATCH v4] PM: sleep: core: Fix runtime PM enabling in device_resume_early()

["Rafael J. Wysocki" <rafael@kernel.org>]

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

Runtime PM should only be enabled in device_resume_early() if it has
been disabled for the given device by device_suspend_late().  Otherwise,
it may cause runtime PM callbacks to run prematurely in some cases
which leads to further functional issues.

Make two changes to address this problem.

First, reorder device_suspend_late() to only disable runtime PM for a
device when it is going to look for the device's callback or if the
device is a "syscore" one.  In all of the other cases, disabling runtime
PM for the device is not in fact necessary.  However, if the device's
callback returns an error and the power.is_late_suspended flag is not
going to be set, enable runtime PM so it only remains disabled when
power.is_late_suspended is set.

Second, make device_resume_early() only enable runtime PM for the
devices with the power.is_late_suspended flag set.

Fixes: 443046d1ad66 ("PM: sleep: Make suspend of devices more asynchronous")
Reported-by: Rose Wu <ya-jou.wu@mediatek.com>
Closes: https://lore.kernel.org/linux-pm/70b25dca6f8c2756d78f076f4a7dee7edaaffc33.camel@mediatek.com/
Cc: 6.16+ <stable@vger.kernel.org> # 6.16+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

v3 -> v4:
   * Reorder the syscore check in device_resume_early() after the
     is_late_suspended check (Ulf)
   * Update the changelog to reflect the above.

v2 -> v3:
   * Also set is_late_suspended for syscore devices to avoid skipping runtime PM
     disabling for them (Ulf).
   * Update the changelog to reflect the above.

v1 -> v2:
   * Add pm_runtime_enable() to device_suspend_late() error path (Rose).
   * Update the changelog to reflect the above.

---
 drivers/base/power/main.c |   25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -903,12 +903,15 @@ static void device_resume_early(struct d
 	TRACE_DEVICE(dev);
 	TRACE_RESUME(0);
 
-	if (dev->power.syscore || dev->power.direct_complete)
+	if (dev->power.direct_complete)
 		goto Out;
 
 	if (!dev->power.is_late_suspended)
 		goto Out;
 
+	if (dev->power.syscore)
+		goto Skip;
+
 	if (!dpm_wait_for_superior(dev, async))
 		goto Out;
 
@@ -941,11 +944,11 @@ Run:
 
 Skip:
 	dev->power.is_late_suspended = false;
+	pm_runtime_enable(dev);
 
 Out:
 	TRACE_RESUME(error);
 
-	pm_runtime_enable(dev);
 	complete_all(&dev->power.completion);
 
 	if (error) {
@@ -1630,12 +1633,6 @@ static void device_suspend_late(struct d
 	TRACE_DEVICE(dev);
 	TRACE_SUSPEND(0);
 
-	/*
-	 * Disable runtime PM for the device without checking if there is a
-	 * pending resume request for it.
-	 */
-	__pm_runtime_disable(dev, false);
-
 	dpm_wait_for_subordinate(dev, async);
 
 	if (READ_ONCE(async_error))
@@ -1646,9 +1643,18 @@ static void device_suspend_late(struct d
 		goto Complete;
 	}
 
-	if (dev->power.syscore || dev->power.direct_complete)
+	if (dev->power.direct_complete)
 		goto Complete;
 
+	/*
+	 * Disable runtime PM for the device without checking if there is a
+	 * pending resume request for it.
+	 */
+	__pm_runtime_disable(dev, false);
+
+	if (dev->power.syscore)
+		goto Skip;
+
 	if (dev->pm_domain) {
 		info = "late power domain ";
 		callback = pm_late_early_op(&dev->pm_domain->ops, state);
@@ -1679,6 +1685,7 @@ Run:
 		WRITE_ONCE(async_error, error);
 		dpm_save_failed_dev(dev_name(dev));
 		pm_dev_err(dev, state, async ? " async late" : " late", error);
+		pm_runtime_enable(dev);
 		goto Complete;
 	}
 	dpm_propagate_wakeup_to_parent(dev);