PCI: Wake-up devices before saving config space for reset

Devices come out of reset in D0.  Restoring a device to a different
post-reset state takes more smarts than our simple config space
restore, which can leave devices in an inconsistent state.  For
example, if a device is reset in D3, but the restore doesn't
successfully return the device to D3, then the actual state of the
device and dev->current_state are contradictory.  Put everything
in D0 going into the reset, then we don't need to do anything
special on the way out.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 12fccc24925c..deb7fa9cc638 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3332,6 +3332,13 @@ static void pci_dev_unlock(struct pci_dev *dev)
 
 static void pci_dev_save_and_disable(struct pci_dev *dev)
 {
+        /*
+         * Wake-up device prior to save.  PM registers default to D0 after
+         * reset and a simple register restore doesn't reliably return
+         * to a non-D0 state anyway.
+         */
+        pci_set_power_state(dev, PCI_D0);
+
         pci_save_state(dev);
         /*
          * Disable the device by clearing the Command register, except for