[PATCH] PM / core: Fix direct_complete handling for devices with no callbacks

From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Linux PM <linux-pm@vger.kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Thomas Martitz <kugel@rockbox.org>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Lukas Wunner <lukas@wunner.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH] PM / core: Fix direct_complete handling for devices with no callbacks
Date: Tue, 22 May 2018 13:02:17 +0200	[thread overview]
Message-ID: <6238546.EnOBWIOf9o@aspire.rjw.lan> (raw)

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

Commit 08810a4119aa (PM / core: Add NEVER_SKIP and SMART_PREPARE
driver flags) inadvertently prevented the power.direct_complete flag
from being set for devices without PM callbacks and with disabled
runtime PM which also prevents power.direct_complete from being set
for their parents.  That led to problems including a resume crash on
HP ZBook 14u.

Restore the previous behavior by causing power.direct_complete to be
set for those devices again, but do that in a more direct way to
avoid overlooking that case in the future.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199693
Fixes: 08810a4119aa (PM / core: Add NEVER_SKIP and SMART_PREPARE driver flags)
Reported-by: Thomas Martitz <kugel@rockbox.org>
Tested-by: Thomas Martitz <kugel@rockbox.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/base/power/main.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

Index: linux-pm/drivers/base/power/main.c
===================================================================

--- linux-pm.orig/drivers/base/power/main.c
+++ linux-pm/drivers/base/power/main.c
@@ -1920,10 +1920,8 @@ static int device_prepare(struct device
 
 	dev->power.wakeup_path = false;
 
-	if (dev->power.no_pm_callbacks) {
-		ret = 1;	/* Let device go direct_complete */
+	if (dev->power.no_pm_callbacks)
 		goto unlock;
-	}
 
 	if (dev->pm_domain)
 		callback = dev->pm_domain->ops.prepare;
@@ -1957,7 +1955,8 @@ unlock:
 	 */
 	spin_lock_irq(&dev->power.lock);
 	dev->power.direct_complete = state.event == PM_EVENT_SUSPEND &&
-		pm_runtime_suspended(dev) && ret > 0 &&
+		((pm_runtime_suspended(dev) && ret > 0) ||
+		 dev->power.no_pm_callbacks) &&
 		!dev_pm_test_driver_flags(dev, DPM_FLAG_NEVER_SKIP);
 	spin_unlock_irq(&dev->power.lock);
 	return 0;
