Messages in this thread | | | Date | Wed, 19 Jun 2019 17:01:24 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH AUTOSEL 4.14 15/31] PCI: PM: Avoid possible suspend-to-idle issue |
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On Tue, Jun 11, 2019 at 05:25:48PM +0200, Rafael J. Wysocki wrote: >On 6/8/2019 1:46 PM, Sasha Levin wrote: >>From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> >> >>[ 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@intel.com> >>Reviewed-by: Keith Busch <keith.busch@intel.com> >>Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com> >>Signed-off-by: Sasha Levin <sashal@kernel.org> >>--- >> 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.
I've dropped it, thank you.
-- Thanks, Sasha
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