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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-05-17 11:08:50 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-05-27 10:55:08 +0200
commitd491f2b75237ef37d8867830ab7fad8d9659e853 (patch)
tree6f7db58fcc91634769ce3dc2bfe7b49b5d9126cd /drivers/pci
parentbb1869012d7b78d1474808cb4c8bd8b272645876 (diff)
PCI: PM: Avoid possible suspend-to-idle issue
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@intel.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Diffstat (limited to 'drivers/pci')
-rw-r--r--drivers/pci/pci-driver.c17
1 files changed, 16 insertions, 1 deletions
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index cae630fe6387..5eadbc3d0969 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -734,6 +734,8 @@ 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);
@@ -827,7 +829,20 @@ 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);