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, 1 insertions, 0 deletions

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 5cd3dce7a24..331857855eb 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -67,6 +67,7 @@ struct pci_platform_pm_ops {
 
 extern int pci_set_platform_pm(struct pci_platform_pm_ops *ops);
 extern void pci_update_current_state(struct pci_dev *dev, pci_power_t state);
+extern void pci_power_up(struct pci_dev *dev);
 extern void pci_disable_enabled_device(struct pci_dev *dev);
 extern int pci_finish_runtime_suspend(struct pci_dev *dev);
 extern int __pci_pme_wakeup(struct pci_dev *dev, void *ign);