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From: Sasha Levin <>
Cc: "Rafael J. Wysocki" <>,
	Keith Busch <>,
	Mika Westerberg <>,
	Sasha Levin <>,
Subject: [PATCH AUTOSEL 4.14 217/371] PCI: PM: Avoid possible suspend-to-idle issue
Date: Thu, 16 Jan 2020 12:21:29 -0500
Message-ID: <> (raw)
In-Reply-To: <>

From: "Rafael J. Wysocki" <>

[ Upstream commit d491f2b75237ef37d8867830ab7fad8d9659e853 ]

If a PCI driver leaves the device handled by it in D0 and calls
pci_save_state() on the device in its ->suspend() or ->suspend_late()
callback, it can expect the device to stay in D0 over the whole
s2idle cycle.  However, that may not be the case if there is a
spurious wakeup while the system is suspended, because in that case
pci_pm_suspend_noirq() will run again after pci_pm_resume_noirq()
which calls pci_restore_state(), via pci_pm_default_resume_early(),
so state_saved is cleared and the second iteration of
pci_pm_suspend_noirq() will invoke pci_prepare_to_sleep() which
may change the power state of the device.

To avoid that, add a new internal flag, skip_bus_pm, that will be set
by pci_pm_suspend_noirq() when it runs for the first time during the
given system suspend-resume cycle if the state of the device has
been saved already and the device is still in D0.  Setting that flag
will cause the next iterations of pci_pm_suspend_noirq() to set
state_saved for pci_pm_resume_noirq(), so that it always restores the
device state from the originally saved data, and avoid calling
pci_prepare_to_sleep() for the device.

Fixes: 33e4f80ee69b ("ACPI / PM: Ignore spurious SCI wakeups from suspend-to-idle")
Signed-off-by: Rafael J. Wysocki <>
Reviewed-by: Keith Busch <>
Reviewed-by: Mika Westerberg <>
Signed-off-by: Sasha Levin <>
 drivers/pci/pci-driver.c | 17 ++++++++++++++++-
 include/linux/pci.h      |  1 +
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 522e59274b5d..1589a147c536 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -728,6 +728,8 @@ static int pci_pm_suspend(struct device *dev)
 	struct pci_dev *pci_dev = to_pci_dev(dev);
 	const struct dev_pm_ops *pm = dev->driver ? dev->driver->pm : NULL;
+	pci_dev->skip_bus_pm = false;
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_suspend(dev, PMSG_SUSPEND);
@@ -801,7 +803,20 @@ static int pci_pm_suspend_noirq(struct device *dev)
-	if (!pci_dev->state_saved) {
+	if (pci_dev->skip_bus_pm) {
+		/*
+		 * The function is running for the second time in a row without
+		 * going through full resume, which is possible only during
+		 * suspend-to-idle in a spurious wakeup case.  Moreover, the
+		 * device was originally left in D0, so its power state should
+		 * not be changed here and the device register values saved
+		 * originally should be restored on resume again.
+		 */
+		pci_dev->state_saved = true;
+	} else if (pci_dev->state_saved) {
+		if (pci_dev->current_state == PCI_D0)
+			pci_dev->skip_bus_pm = true;
+	} else {
 		if (pci_power_manageable(pci_dev))
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 59f4d10568c6..430f3c335446 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -346,6 +346,7 @@ struct pci_dev {
 						   D3cold, not set for devices
 						   powered on/off by the
 						   corresponding bridge */
+	unsigned int	skip_bus_pm:1;	/* Internal: Skip bus-level PM */
 	unsigned int	ignore_hotplug:1;	/* Ignore hotplug events */
 	unsigned int	hotplug_user_indicators:1; /* SlotCtl indicators
 						      controlled exclusively by

      parent reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
2020-01-16 17:19 ` [PATCH AUTOSEL 4.14 097/371] PCI: endpoint: functions: Use memcpy_fromio()/memcpy_toio() Sasha Levin
2020-01-16 17:21 ` Sasha Levin [this message]

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