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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-06-14 00:59:45 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2019-06-14 01:03:27 +0300
commit3e26c5feed2add218046ecf91bab3cfa9bf762a6 (patch)
treea489eff6016489db4d51a0a57cfe008928ad21f7 /drivers/pci/pci-driver.c
parentd1fdb6d8f6a4109a4263176c84b899076a5f8008 (diff)
downloadlinux-3e26c5feed2add218046ecf91bab3cfa9bf762a6.tar.xz
PCI: PM: Skip devices in D0 for suspend-to-idle
Commit d491f2b75237 ("PCI: PM: Avoid possible suspend-to-idle issue") attempted to avoid a problem with devices whose drivers want them to stay in D0 over suspend-to-idle and resume, but it did not go as far as it should with that. Namely, first of all, the power state of a PCI bridge with a downstream device in D0 must be D0 (based on the PCI PM spec r1.2, sec 6, table 6-1, if the bridge is not in D0, there can be no PCI transactions on its secondary bus), but that is not actively enforced during system-wide PM transitions, so use the skip_bus_pm flag introduced by commit d491f2b75237 for that. Second, the configuration of devices left in D0 (whatever the reason) during suspend-to-idle need not be changed and attempting to put them into D0 again by force is pointless, so explicitly avoid doing that. Fixes: d491f2b75237 ("PCI: PM: Avoid possible suspend-to-idle issue") Reported-by: Kai-Heng Feng <kai.heng.feng@canonical.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Diffstat (limited to 'drivers/pci/pci-driver.c')
-rw-r--r--drivers/pci/pci-driver.c47
1 files changed, 35 insertions, 12 deletions
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 5eadbc3d0969..98af9ecd4a90 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -524,7 +524,6 @@ static void pci_pm_default_resume_early(struct pci_dev *pci_dev)
pci_power_up(pci_dev);
pci_restore_state(pci_dev);
pci_pme_restore(pci_dev);
- pci_fixup_device(pci_fixup_resume_early, pci_dev);
}
/*
@@ -831,18 +830,16 @@ static int pci_pm_suspend_noirq(struct device *dev)
if (pci_dev->skip_bus_pm) {
/*
- * The function is running for the second time in a row without
+ * Either the device is a bridge with a child in D0 below it, or
+ * 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.
+ * suspend-to-idle in a spurious wakeup case. The device should
+ * be in D0 at this point, but if it is a bridge, it may be
+ * necessary to save its state.
*/
- 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_dev->state_saved)
+ pci_save_state(pci_dev);
+ } else if (!pci_dev->state_saved) {
pci_save_state(pci_dev);
if (pci_power_manageable(pci_dev))
pci_prepare_to_sleep(pci_dev);
@@ -851,6 +848,22 @@ static int pci_pm_suspend_noirq(struct device *dev)
dev_dbg(dev, "PCI PM: Suspend power state: %s\n",
pci_power_name(pci_dev->current_state));
+ if (pci_dev->current_state == PCI_D0) {
+ pci_dev->skip_bus_pm = true;
+ /*
+ * Per PCI PM r1.2, table 6-1, a bridge must be in D0 if any
+ * downstream device is in D0, so avoid changing the power state
+ * of the parent bridge by setting the skip_bus_pm flag for it.
+ */
+ if (pci_dev->bus->self)
+ pci_dev->bus->self->skip_bus_pm = true;
+ }
+
+ if (pci_dev->skip_bus_pm && !pm_suspend_via_firmware()) {
+ dev_dbg(dev, "PCI PM: Skipped\n");
+ goto Fixup;
+ }
+
pci_pm_set_unknown_state(pci_dev);
/*
@@ -898,7 +911,16 @@ static int pci_pm_resume_noirq(struct device *dev)
if (dev_pm_smart_suspend_and_suspended(dev))
pm_runtime_set_active(dev);
- pci_pm_default_resume_early(pci_dev);
+ /*
+ * In the suspend-to-idle case, devices left in D0 during suspend will
+ * stay in D0, so it is not necessary to restore or update their
+ * configuration here and attempting to put them into D0 again may
+ * confuse some firmware, so avoid doing that.
+ */
+ if (!pci_dev->skip_bus_pm || pm_suspend_via_firmware())
+ pci_pm_default_resume_early(pci_dev);
+
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
if (pci_has_legacy_pm_support(pci_dev))
return pci_legacy_resume_early(dev);
@@ -1194,6 +1216,7 @@ static int pci_pm_restore_noirq(struct device *dev)
}
pci_pm_default_resume_early(pci_dev);
+ pci_fixup_device(pci_fixup_resume_early, pci_dev);
if (pci_has_legacy_pm_support(pci_dev))
return pci_legacy_resume_early(dev);