Commit:     691cd0c2ee2d4d6dff652627fca1b2d4f1377d58
Parent:     4516a618a76eae6eb1b37259ad49f39b7b7f33d8
Author:     Andreas Block <[EMAIL PROTECTED]>
AuthorDate: Mon Feb 5 16:36:07 2007 -0800
Committer:  Greg Kroah-Hartman <[EMAIL PROTECTED]>
CommitDate: Fri Feb 16 15:30:10 2007 -0800

    PCI: PCI devices get assigned redundant IRQs
    I'm currently working on a port to a CPCI board with a MPC5200.  When
    testing the PCI interrupt routing, I discovered the following: Even devices
    which don't use interrupts (-> PCI Spec.: Interrupt Pin Register is zero),
    get an interrupt assigned (this is at least true for most of the
    PPC-targets I looked at).
    The cause is pretty obvious in drivers/pci/setup-irq.c.  I guess at least
    in an ideal world with correctly designed hardware, the code should rather
    look as in the patch below.
    Of course it doesn't hurt anybody to have an unuseable IRQ assigned to a
    PCI-to-PCI-bridge (or something alike), but to me it seems a bit strange.
    Please correct me, if I'm mislead.
    The patch below is tested on the above mentioned CPCI-MPC5200 board and is
    compiler tested with the latest git-repository kernel on x86.
    Cc: "Eric W. Biederman" <[EMAIL PROTECTED]>
    Cc: Thomas Gleixner <[EMAIL PROTECTED]>
    Cc: Ingo Molnar <[EMAIL PROTECTED]>
    Cc: Linus Torvalds <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
 drivers/pci/setup-irq.c |   18 ++++++++++--------
 1 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/setup-irq.c b/drivers/pci/setup-irq.c
index a251289..568f187 100644
--- a/drivers/pci/setup-irq.c
+++ b/drivers/pci/setup-irq.c
@@ -24,7 +24,7 @@ pdev_fixup_irq(struct pci_dev *dev,
               int (*map_irq)(struct pci_dev *, u8, u8))
        u8 pin, slot;
-       int irq;
+       int irq = 0;
        /* If this device is not on the primary bus, we need to figure out
           which interrupt pin it will come in on.   We know which slot it
@@ -33,16 +33,18 @@ pdev_fixup_irq(struct pci_dev *dev,
           apply the swizzle function.  */
        pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
-       /* Cope with 0 and illegal. */
-       if (pin == 0 || pin > 4)
+       /* Cope with illegal. */
+       if (pin > 4)
                pin = 1;
-       /* Follow the chain of bridges, swizzling as we go.  */
-       slot = (*swizzle)(dev, &pin);
+       if (pin != 0) {
+               /* Follow the chain of bridges, swizzling as we go.  */
+               slot = (*swizzle)(dev, &pin);
-       irq = (*map_irq)(dev, slot, pin);
-       if (irq == -1)
-               irq = 0;
+               irq = (*map_irq)(dev, slot, pin);
+               if (irq == -1)
+                       irq = 0;
+       }
        dev->irq = irq;
        pr_debug("PCI: fixup irq: (%s) got %d\n",
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