From 691cd0c2ee2d4d6dff652627fca1b2d4f1377d58 Mon Sep 17 00:00:00 2001 From: Andreas Block Date: Mon, 5 Feb 2007 16:36:07 -0800 Subject: [PATCH] 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" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Linus Torvalds Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/pci/setup-irq.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/pci/setup-irq.c b/drivers/pci/setup-irq.c index a251289c9958..568f1877315c 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",