[PATCH] pci: only call pci_restore_bars at boot

Certain (SGI?) ia64 boxes object to having their PCI BARs
restored unless absolutely necessary. This patch restricts calling
pci_restore_bars from pci_set_power_state unless the current state
is PCI_UNKNOWN, the actual (i.e. physical) state of the device is
PCI_D3hot, and the device indicates that it will lose its configuration
when transitioning to PCI_D0.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 12 insertions, 4 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 992db89adce7..259d247b7551 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -309,17 +309,25 @@ pci_set_power_state(struct pci_dev *dev, pci_power_t state)
 
         pci_read_config_word(dev, pm + PCI_PM_CTRL, &pmcsr);
 
-        /* If we're in D3, force entire word to 0.
+        /* If we're (effectively) in D3, force entire word to 0.
          * This doesn't affect PME_Status, disables PME_En, and
          * sets PowerState to 0.
          */
-        if (dev->current_state >= PCI_D3hot) {
-                if (!(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))
+        switch (dev->current_state) {
+        case PCI_UNKNOWN: /* Boot-up */
+                if ((pmcsr & PCI_PM_CTRL_STATE_MASK) == PCI_D3hot
+                 && !(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET))
                         need_restore = 1;
+                /* Fall-through: force to D0 */
+        case PCI_D3hot:
+        case PCI_D3cold:
+        case PCI_POWER_ERROR:
                 pmcsr = 0;
-        } else {
+                break;
+        default:
                 pmcsr &= ~PCI_PM_CTRL_STATE_MASK;
                 pmcsr |= state;
+                break;
         }
 
         /* enter specified state */