[PATCH] pci: only call pci_restore_bars at boot
John W. Linville [Wed, 14 Sep 2005 13:52:42 +0000 (09:52 -0400)]
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>

drivers/pci/pci.c

index 992db89..259d247 100644 (file)
@@ -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 */