In arch/i386/kernel/pci-irq.c:pcibios_enable_irq(), there is a redundant check:

    if (pin && !pcibios_lookup_irq(dev, 1) && !dev->irq) {

        /* ... */

        if (pin) {


We don't need the second 'if (pin)', as we already know it's nonzero from the first check. Also note that this fixes the following warning (which happens because gcc's isn't always perfect with determining whether a variable is used uninitialized):


pci-irq.c: In function `pcibios_enable_irq':
pci-irq.c:1128: warning: 'msg' might be used uninitialized in this function

All the patch does is remove the duplicate check and shift everything else over.


Mark F. Haigh [EMAIL PROTECTED]
--- arch/i386/kernel/pci-irq.c.orig     2005-02-02 18:33:56.694474944 -0800
+++ arch/i386/kernel/pci-irq.c  2005-02-02 18:58:18.828196832 -0800
@@ -1134,36 +1134,34 @@
                if (io_apic_assign_pci_irqs) {
                        int irq;
 
-                       if (pin) {
-                               pin--;          /* interrupt pins are numbered 
starting from 1 */
-                               irq = 
IO_APIC_get_PCI_irq_vector(dev->bus->number, PCI_SLOT(dev->devfn), pin);
-                               /*
-                                * Busses behind bridges are typically not 
listed in the MP-table.
-                                * In this case we have to look up the IRQ 
based on the parent bus,
-                                * parent slot, and pin number. The SMP code 
detects such bridged
-                                * busses itself so we should get into this 
branch reliably.
-                                */
-                               temp_dev = dev;
-                               while (irq < 0 && dev->bus->parent) { /* go 
back to the bridge */
-                                       struct pci_dev * bridge = 
dev->bus->self;
+                       pin--;          /* interrupt pins are numbered starting 
from 1 */
+                       irq = IO_APIC_get_PCI_irq_vector(dev->bus->number, 
PCI_SLOT(dev->devfn), pin);
+                       /*
+                        * Busses behind bridges are typically not listed in 
the MP-table.
+                        * In this case we have to look up the IRQ based on the 
parent bus,
+                        * parent slot, and pin number. The SMP code detects 
such bridged
+                        * busses itself so we should get into this branch 
reliably.
+                        */
+                       temp_dev = dev;
+                       while (irq < 0 && dev->bus->parent) { /* go back to the 
bridge */
+                               struct pci_dev * bridge = dev->bus->self;
 
-                                       pin = (pin + PCI_SLOT(dev->devfn)) % 4;
-                                       irq = 
IO_APIC_get_PCI_irq_vector(bridge->bus->number, 
-                                                       
PCI_SLOT(bridge->devfn), pin);
-                                       if (irq >= 0)
-                                               printk(KERN_WARNING "PCI: using 
PPB(B%d,I%d,P%d) to get irq %d\n", 
-                                                       bridge->bus->number, 
PCI_SLOT(bridge->devfn), pin, irq);
-                                       dev = bridge;
-                               }
-                               dev = temp_dev;
-                               if (irq >= 0) {
-                                       printk(KERN_INFO "PCI->APIC IRQ 
transform: (B%d,I%d,P%d) -> %d\n",
-                                               dev->bus->number, 
PCI_SLOT(dev->devfn), pin, irq);
-                                       dev->irq = irq;
-                                       return;
-                               } else
-                                       msg = " Probably buggy MP table.";
+                               pin = (pin + PCI_SLOT(dev->devfn)) % 4;
+                               irq = 
IO_APIC_get_PCI_irq_vector(bridge->bus->number, 
+                                               PCI_SLOT(bridge->devfn), pin);
+                               if (irq >= 0)
+                                       printk(KERN_WARNING "PCI: using 
PPB(B%d,I%d,P%d) to get irq %d\n", 
+                                               bridge->bus->number, 
PCI_SLOT(bridge->devfn), pin, irq);
+                               dev = bridge;
                        }
+                       dev = temp_dev;
+                       if (irq >= 0) {
+                               printk(KERN_INFO "PCI->APIC IRQ transform: 
(B%d,I%d,P%d) -> %d\n",
+                                       dev->bus->number, PCI_SLOT(dev->devfn), 
pin, irq);
+                               dev->irq = irq;
+                               return;
+                       } else
+                               msg = " Probably buggy MP table.";
                } else if (pci_probe & PCI_BIOS_IRQ_SCAN)
                        msg = "";
                else

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