From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Notice that if pci_power_up() returns success early, without updating
the given device's PCI_PM_CTRL register, because it has verified that
the power state of the device is D0 already at that point, the
pci_update_current_state() invocation in pci_pm_default_resume_early()
is redundant.
Avoid that redundant call by making pci_power_up() return 1 when it
has updated the device's PCI_PM_CTRL register and checking its return
value in pci_pm_default_resume_early().
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
New patch in v2.
---
drivers/pci/pci-driver.c | 5 +++--
drivers/pci/pci.c | 10 ++++++++--
2 files changed, 11 insertions(+), 4 deletions(-)
Index: linux-pm/drivers/pci/pci-driver.c
===================================================================
--- linux-pm.orig/drivers/pci/pci-driver.c
+++ linux-pm/drivers/pci/pci-driver.c
@@ -553,8 +553,9 @@ static void pci_pm_default_resume(struct
static void pci_pm_default_resume_early(struct pci_dev *pci_dev)
{
- pci_power_up(pci_dev);
- pci_update_current_state(pci_dev, PCI_D0);
+ if (pci_power_up(pci_dev))
+ pci_update_current_state(pci_dev, PCI_D0);
+
pci_restore_state(pci_dev);
pci_pme_restore(pci_dev);
}
Index: linux-pm/drivers/pci/pci.c
===================================================================
--- linux-pm.orig/drivers/pci/pci.c
+++ linux-pm/drivers/pci/pci.c
@@ -1189,6 +1189,12 @@ static int pci_dev_wait(struct pci_dev *
/**
* pci_power_up - Put the given device into D0
* @dev: PCI device to power up
+ *
+ * Use the platform firmware and the PCI_PM_CTRL register to put @dev into D0.
+ *
+ * Return 0 if invoking the platform firmware was sufficient to put @dev into D0
+ * (and so the PCI_PM_CTRL register was not updated), or 1 if it was necessary to
+ * update the PCI_PM_CTRL register, or -ENODEV if the device was not accessible.
*/
int pci_power_up(struct pci_dev *dev)
{
@@ -1235,7 +1241,7 @@ int pci_power_up(struct pci_dev *dev)
udelay(PCI_PM_D2_DELAY);
dev->current_state = PCI_D0;
- return 0;
+ return 1;
fail:
pci_err(dev, "Unable to change power state to D0, device inaccessible\n");
@@ -1273,7 +1279,7 @@ static int pci_set_full_power_state(stru
int ret;
ret = pci_power_up(dev);
- if (ret)
+ if (ret < 0)
return ret;
if (!dev->pm_cap)
