Re: [PATCH AUTOSEL 4.14 15/31] PCI: PM: Avoid possible suspend-to-idle issue

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 6/8/2019 1:46 PM, Sasha Levin wrote:
From: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>

[ 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 <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Keith Busch <keith.busch@xxxxxxxxx>
Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
  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 ea69b4dbab66..f5d66335fe53 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -726,6 +726,8 @@ 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);
@@ -799,7 +801,20 @@ 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 {
  		pci_save_state(pci_dev);
  		if (pci_power_manageable(pci_dev))
  			pci_prepare_to_sleep(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

This has been reported to be problematic, I wouldn't recommend taking it for -stable at this point.





[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux