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Subject[PATCH v2 1/5] PM: ACPI/PCI: Resume all devices during hibernation
Date
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Both the PCI bus type and the ACPI PM domain avoid resuming
runtime-suspended devices with DPM_FLAG_SMART_SUSPEND set during
hibernation (before creating the snapshot image of system memory),
but that turns out to be a mistake. It leads to functional issues
and adds complexity that's hard to justify.

For this reason, resume all runtime-suspended PCI devices and all
devices in the ACPI PM domains before creating a snapshot image of
system memory during hibernation.

Fixes: 05087360fd7a (ACPI / PM: Take SMART_SUSPEND driver flag into account)
Fixes: c4b65157aeef (PCI / PM: Take SMART_SUSPEND driver flag into account)
Link: https://lore.kernel.org/linux-acpi/917d4399-2e22-67b1-9d54-808561f9083f@uwyo.edu/T/#maf065fe6e4974f2a9d79f332ab99dfaba635f64c
Reported-by: Robert R. Howell <RHowell@uwyo.edu>
Tested-by: Robert R. Howell <RHowell@uwyo.edu>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

-> v2: No changes.

---
drivers/acpi/device_pm.c | 13 +++++++------
drivers/pci/pci-driver.c | 16 ++++++++--------
2 files changed, 15 insertions(+), 14 deletions(-)

Index: linux-pm/drivers/acpi/device_pm.c
===================================================================
--- linux-pm.orig/drivers/acpi/device_pm.c
+++ linux-pm/drivers/acpi/device_pm.c
@@ -1155,13 +1155,14 @@ EXPORT_SYMBOL_GPL(acpi_subsys_resume_ear
int acpi_subsys_freeze(struct device *dev)
{
/*
- * This used to be done in acpi_subsys_prepare() for all devices and
- * some drivers may depend on it, so do it here. Ideally, however,
- * runtime-suspended devices should not be touched during freeze/thaw
- * transitions.
+ * Resume all runtime-suspended devices before creating a snapshot
+ * image of system memory, because the restore kernel generally cannot
+ * be expected to always handle them consistently and they need to be
+ * put into the runtime-active metastate during system resume anyway,
+ * so it is better to ensure that the state saved in the image will be
+ * alwyas consistent with that.
*/
- if (!dev_pm_test_driver_flags(dev, DPM_FLAG_SMART_SUSPEND))
- pm_runtime_resume(dev);
+ pm_runtime_resume(dev);

return pm_generic_freeze(dev);
}
Index: linux-pm/drivers/pci/pci-driver.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-driver.c
+++ linux-pm/drivers/pci/pci-driver.c
@@ -1012,15 +1012,15 @@ static int pci_pm_freeze(struct device *
}

/*
- * This used to be done in pci_pm_prepare() for all devices and some
- * drivers may depend on it, so do it here. Ideally, runtime-suspended
- * devices should not be touched during freeze/thaw transitions,
- * however.
+ * Resume all runtime-suspended devices before creating a snapshot
+ * image of system memory, because the restore kernel generally cannot
+ * be expected to always handle them consistently and they need to be
+ * put into the runtime-active metastate during system resume anyway,
+ * so it is better to ensure that the state saved in the image will be
+ * alwyas consistent with that.
*/
- if (!dev_pm_smart_suspend_and_suspended(dev)) {
- pm_runtime_resume(dev);
- pci_dev->state_saved = false;
- }
+ pm_runtime_resume(dev);
+ pci_dev->state_saved = false;

if (pm->freeze) {
int error;



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