--- linux-2.4.21-106/drivers/acpi/pci_irq.c	Tue Sep 30 07:14:55 2003
+++ pci_irq.c	Mon Oct 20 17:22:34 2003
@@ -376,7 +376,7 @@
 	struct pci_dev		*dev,
 	int			pin)
 {
-	struct pci_dev		*bridge = dev;
+	struct pci_dev		*curr = dev;
 	int			irq = 0;
 
 	ACPI_FUNCTION_TRACE("acpi_pci_irq_derive");
@@ -388,11 +388,19 @@
 	 * Attempt to derive an IRQ for this device from a parent bridge's
 	 * PCI interrupt routing entry (a.k.a. the "bridge swizzle").
 	 */
-	while (!irq && bridge->bus->self) {
-		pin = (pin + PCI_SLOT(bridge->devfn)) % 4;
-		bridge = bridge->bus->self;
-		irq = acpi_pci_irq_lookup(0, bridge->bus->number, PCI_SLOT(bridge->devfn), pin);
-	}
+	do {
+		irq = acpi_pci_irq_lookup(0, curr->bus->number, PCI_SLOT(curr->devfn), pin);
+
+		if (irq) break; 
+         
+		/*
+		* Bridge swizzle step
+		*/
+		pin = (pin + PCI_SLOT(curr->devfn)) % 4;
+		curr = curr->bus->self;
+
+	} while (curr);
+
 
 	if (!irq) {
 		ACPI_DEBUG_PRINT((ACPI_DB_WARN, "Unable to derive IRQ for device %s\n", dev->slot_name));
@@ -433,15 +441,10 @@
 	/* 
 	 * First we check the PCI IRQ routing table (PRT) for an IRQ.  PRT
 	 * values override any BIOS-assigned IRQs set during boot.
-	 */
- 	irq = acpi_pci_irq_lookup(0, dev->bus->number, PCI_SLOT(dev->devfn), pin);
- 
-	/*
 	 * If no PRT entry was found, we'll try to derive an IRQ from the
 	 * device's parent bridge.
 	 */
-	if (!irq)
- 		irq = acpi_pci_irq_derive(dev, pin);
+ 	irq = acpi_pci_irq_derive(dev, pin);
  
 	/*
 	 * No IRQ known to the ACPI subsystem - maybe the BIOS /