PCI / PM: Avoid resuming PCI devices during system suspend
Commit f25c0ae2b4c4 (ACPI / PM: Avoid resuming devices in ACPI PM
domain during system suspend) modified the ACPI PM domain's system
suspend callbacks to allow devices attached to it to be left in the
runtime-suspended state during system suspend so as to optimize
the suspend process.
This was based on the general mechanism introduced by commit
aae4518b3124 (PM / sleep: Mechanism to avoid resuming runtime-suspended
devices unnecessarily).
Extend that approach to PCI devices by modifying the PCI bus type's
->prepare callback to return 1 for devices that are runtime-suspended
when it is being executed and that are in a suitable power state and
need not be resumed going forward.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
index 887e6bd..741023e 100644
--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -653,7 +653,6 @@
static int pci_pm_prepare(struct device *dev)
{
struct device_driver *drv = dev->driver;
- int error = 0;
/*
* Devices having power.ignore_children set may still be necessary for
@@ -662,10 +661,12 @@
if (dev->power.ignore_children)
pm_runtime_resume(dev);
- if (drv && drv->pm && drv->pm->prepare)
- error = drv->pm->prepare(dev);
-
- return error;
+ if (drv && drv->pm && drv->pm->prepare) {
+ int error = drv->pm->prepare(dev);
+ if (error)
+ return error;
+ }
+ return pci_dev_keep_suspended(to_pci_dev(dev));
}