linux-kernel - [PATCH] drivers: core: Detach device from power domain on shutdown

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Date:   Tue,  1 Dec 2020 13:30:19 -0800
From:   Furquan Shaikh <furquan@...gle.com>
To:     "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        Furquan Shaikh <furquan@...gle.com>
Subject: [PATCH] drivers: core: Detach device from power domain on shutdown

When the system is powered off or rebooted, devices are not detached
from their PM domain. This results in ACPI PM not being invoked and
hence PowerResouce _OFF method not being invoked for any of the
devices. Because the ACPI power resources are not turned off in case
of poweroff and reboot, it violates the power sequencing requirements
which impacts the reliability of the devices over the lifetime of the
platform. This is currently observed on all Chromebooks using ACPI.

In order to solve the above problem, this change detaches a device
from its PM domain whenever it is shutdown. This action is basically
analogous to ->remove() from driver model perspective. Detaching the
device from its PM domain ensures that the ACPI PM gets a chance to
turn off the power resources for the device thus complying with its
power sequencing requirements.

Signed-off-by: Furquan Shaikh <furquan@...gle.com>
---
 drivers/base/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index d661ada1518f..5823f1d719e1 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -23,6 +23,7 @@
 #include <linux/of_device.h>
 #include <linux/genhd.h>
 #include <linux/mutex.h>
+#include <linux/pm_domain.h>
 #include <linux/pm_runtime.h>
 #include <linux/netdevice.h>
 #include <linux/sched/signal.h>
@@ -4057,6 +4058,8 @@ void device_shutdown(void)
 			dev->driver->shutdown(dev);
 		}

+		dev_pm_domain_detach(dev, true);
+
 		device_unlock(dev);
 		if (parent)
 			device_unlock(parent);
-- 
2.29.2.454.gaff20da3a2-goog