PCI PM: Avoid touching devices behind bridges in unknown state
It generally is better to avoid accessing devices behind bridges that
may not be in the D0 power state, because in that case the bridges'
secondary buses may not be accessible. For this reason, during the
early phase of resume (ie. with interrupts disabled), before
restoring the standard config registers of a device, check the power
state of the bridge the device is behind and postpone the restoration
of the device's config space, as well as any other operations that
would involve accessing the device, if that state is not D0.
In such cases the restoration of the device's config space will be
retried during the "normal" phase of resume (ie. with interrupts
enabled), so that the bridge can be put into D0 before that happens.
Also, save standard configuration registers of PCI devices during the
"normal" phase of suspend (ie. with interrupts enabled), so that the
bridges the devices are behind can be put into low power states (we
don't put bridges into low power states at the moment, but we may
want to do it in the future and it seems reasonable to design for
that).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index bfaa77d..750ee79 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -316,21 +316,10 @@
/*
* Default "suspend" method for devices that have no driver provided suspend,
- * or not even a driver at all (first part).
- */
-static void pci_default_pm_suspend_early(struct pci_dev *pci_dev)
-{
- /* If device is enabled at this point, disable it */
- pci_disable_enabled_device(pci_dev);
-}
-
-/*
- * Default "suspend" method for devices that have no driver provided suspend,
* or not even a driver at all (second part).
*/
static void pci_default_pm_suspend_late(struct pci_dev *pci_dev)
{
- pci_save_state(pci_dev);
/*
* mark its power state as "unknown", since we don't know if
* e.g. the BIOS will change its device state when we suspend.
@@ -341,16 +330,6 @@
/*
* Default "resume" method for devices that have no driver provided resume,
- * or not even a driver at all (first part).
- */
-static void pci_default_pm_resume_early(struct pci_dev *pci_dev)
-{
- /* restore the PCI config space */
- pci_restore_state(pci_dev);
-}
-
-/*
- * Default "resume" method for devices that have no driver provided resume,
* or not even a driver at all (second part).
*/
static int pci_default_pm_resume_late(struct pci_dev *pci_dev)
@@ -379,9 +358,10 @@
i = drv->suspend(pci_dev, state);
suspend_report_result(drv->suspend, i);
} else {
+ pci_save_state(pci_dev);
/*
- * For compatibility with existing code with legacy PM support
- * don't call pci_default_pm_suspend_early() here.
+ * This is for compatibility with existing code with legacy PM
+ * support.
*/
pci_default_pm_suspend_late(pci_dev);
}
@@ -410,7 +390,8 @@
if (drv && drv->resume) {
error = drv->resume(pci_dev);
} else {
- pci_default_pm_resume_early(pci_dev);
+ /* restore the PCI config space */
+ pci_restore_state(pci_dev);
error = pci_default_pm_resume_late(pci_dev);
}
return error;
@@ -429,22 +410,72 @@
/* Auxiliary functions used by the new power management framework */
+static int pci_restore_standard_config(struct pci_dev *pci_dev)
+{
+ struct pci_dev *parent = pci_dev->bus->self;
+ int error = 0;
+
+ /* Check if the device's bus is operational */
+ if (!parent || parent->current_state == PCI_D0) {
+ pci_restore_state(pci_dev);
+ pci_update_current_state(pci_dev, PCI_D0);
+ } else {
+ dev_warn(&pci_dev->dev, "unable to restore config, "
+ "bridge %s in low power state D%d\n", pci_name(parent),
+ parent->current_state);
+ pci_dev->current_state = PCI_UNKNOWN;
+ error = -EAGAIN;
+ }
+
+ return error;
+}
+
static bool pci_is_bridge(struct pci_dev *pci_dev)
{
return !!(pci_dev->subordinate);
}
+static void pci_pm_default_resume_noirq(struct pci_dev *pci_dev)
+{
+ if (pci_restore_standard_config(pci_dev))
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
+}
+
static int pci_pm_default_resume(struct pci_dev *pci_dev)
{
+ /*
+ * pci_restore_standard_config() should have been called once already,
+ * but it would have failed if the device's parent bridge had not been
+ * in power state D0 at that time. Check it and try again if necessary.
+ */
+ if (pci_dev->current_state == PCI_UNKNOWN) {
+ int error = pci_restore_standard_config(pci_dev);
+ if (error)
+ return error;
+ }
+
+ pci_fixup_device(pci_fixup_resume, pci_dev);
+
if (!pci_is_bridge(pci_dev))
pci_enable_wake(pci_dev, PCI_D0, false);
return pci_default_pm_resume_late(pci_dev);
}
+static void pci_pm_default_suspend_generic(struct pci_dev *pci_dev)
+{
+ /* If device is enabled at this point, disable it */
+ pci_disable_enabled_device(pci_dev);
+ /*
+ * Save state with interrupts enabled, because in principle the bus the
+ * device is on may be put into a low power state after this code runs.
+ */
+ pci_save_state(pci_dev);
+}
+
static void pci_pm_default_suspend(struct pci_dev *pci_dev)
{
- pci_default_pm_suspend_early(pci_dev);
+ pci_pm_default_suspend_generic(pci_dev);
if (!pci_is_bridge(pci_dev))
pci_prepare_to_sleep(pci_dev);
@@ -529,12 +560,13 @@
struct device_driver *drv = dev->driver;
int error = 0;
- pci_fixup_device(pci_fixup_resume, pci_dev);
-
if (drv && drv->pm) {
+ pci_fixup_device(pci_fixup_resume, pci_dev);
+
if (drv->pm->resume)
error = drv->pm->resume(dev);
} else if (pci_has_legacy_pm_support(pci_dev)) {
+ pci_fixup_device(pci_fixup_resume, pci_dev);
error = pci_legacy_resume(dev);
} else {
error = pci_pm_default_resume(pci_dev);
@@ -549,15 +581,16 @@
struct device_driver *drv = dev->driver;
int error = 0;
- pci_fixup_device(pci_fixup_resume_early, to_pci_dev(dev));
-
if (drv && drv->pm) {
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
+
if (drv->pm->resume_noirq)
error = drv->pm->resume_noirq(dev);
} else if (pci_has_legacy_pm_support(pci_dev)) {
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
error = pci_legacy_resume_early(dev);
} else {
- pci_default_pm_resume_early(pci_dev);
+ pci_pm_default_resume_noirq(pci_dev);
}
return error;
@@ -589,7 +622,7 @@
error = pci_legacy_suspend(dev, PMSG_FREEZE);
pci_fixup_device(pci_fixup_suspend, pci_dev);
} else {
- pci_default_pm_suspend_early(pci_dev);
+ pci_pm_default_suspend_generic(pci_dev);
}
return error;
@@ -647,7 +680,7 @@
pci_fixup_device(pci_fixup_resume_early, to_pci_dev(dev));
error = pci_legacy_resume_early(dev);
} else {
- pci_default_pm_resume_early(pci_dev);
+ pci_update_current_state(pci_dev, PCI_D0);
}
return error;
@@ -698,12 +731,13 @@
struct device_driver *drv = dev->driver;
int error = 0;
- pci_fixup_device(pci_fixup_resume, pci_dev);
-
if (drv && drv->pm) {
+ pci_fixup_device(pci_fixup_resume, pci_dev);
+
if (drv->pm->restore)
error = drv->pm->restore(dev);
} else if (pci_has_legacy_pm_support(pci_dev)) {
+ pci_fixup_device(pci_fixup_resume, pci_dev);
error = pci_legacy_resume(dev);
} else {
error = pci_pm_default_resume(pci_dev);
@@ -718,15 +752,16 @@
struct device_driver *drv = dev->driver;
int error = 0;
- pci_fixup_device(pci_fixup_resume_early, pci_dev);
-
if (drv && drv->pm) {
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
+
if (drv->pm->restore_noirq)
error = drv->pm->restore_noirq(dev);
} else if (pci_has_legacy_pm_support(pci_dev)) {
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
error = pci_legacy_resume_early(dev);
} else {
- pci_default_pm_resume_early(pci_dev);
+ pci_pm_default_resume_noirq(pci_dev);
}
return error;