PCI / PM: restore the original behavior of pci_set_power_state()

Commit cc2893b6 (PCI: Ensure we re-enable devices on resume)
addressed the problem with USB not being powered after resume on
recent Lenovo machines, but it did that in a suboptimal way.
Namely, it should have changed the relevant code paths only,
which are pci_pm_resume_noirq() and pci_pm_restore_noirq() supposed
to restore the device's power and standard configuration registers
after system resume from suspend or hibernation.  Instead, however,
it modified pci_set_power_state() which is executed in several
other situations too.  That resulted in some undesirable effects,
like attempting to change a device's power state in the same way
multiple times in a row (up to as many as 4 times in a row in the
snd_hda_intel driver).

Fix the bug addressed by commit cc2893b6 in an alternative way,
by forcibly powering up all devices in pci_pm_default_resume_early(),
which is called by pci_pm_resume_noirq() and pci_pm_restore_noirq()
to restore the device's power and standard configuration registers,
and modifying pci_pm_runtime_resume() to avoid the forcible power-up
if not necessary.  Then, revert the changes made by commit cc2893b6
to make the confusion introduced by it go away.

Acked-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 8effb9b23eec..acae2705e7f6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -673,6 +673,19 @@ void pci_update_current_state(struct pci_dev *dev, pci_power_t state)
 }
 
 /**
+ * pci_power_up - Put the given device into D0 forcibly
+ * @dev: PCI device to power up
+ */
+void pci_power_up(struct pci_dev *dev)
+{
+        if (platform_pci_power_manageable(dev))
+                platform_pci_set_power_state(dev, PCI_D0);
+
+        pci_raw_set_power_state(dev, PCI_D0);
+        pci_update_current_state(dev, PCI_D0);
+}
+
+/**
  * pci_platform_power_transition - Use platform to change device power state
  * @dev: PCI device to handle.
  * @state: State to put the device into.
@@ -762,7 +775,7 @@ int __pci_complete_power_transition(struct pci_dev *dev, pci_power_t state)
 {
         int ret;
 
-        if (state < PCI_D0)
+        if (state <= PCI_D0)
                 return -EINVAL;
         ret = pci_platform_power_transition(dev, state);
         /* Power off the bridge may power off the whole hierarchy */
@@ -804,6 +817,10 @@ int pci_set_power_state(struct pci_dev *dev, pci_power_t state)
                  */
                 return 0;
 
+        /* Check if we're already there */
+        if (dev->current_state == state)
+                return 0;
+
         __pci_start_power_transition(dev, state);
 
         /* This device is quirked not to be put into D3, so