From e0c1e9bf81badc7ba59e120d6218101903d5d103 Mon Sep 17 00:00:00 2001 From: Kimball Murray Date: Mon, 8 May 2006 15:17:16 +0200 Subject: [PATCH] x86_64: avoid IRQ0 ioapic pin collision The patch addresses a problem with ACPI SCI interrupt entry, which gets re-used, and the IRQ is assigned to another unrelated device. The patch corrects the code such that SCI IRQ is skipped and duplicate entry is avoided. Second issue came up with VIA chipset, the problem was caused by original patch assigning IRQs starting 16 and up. The VIA chipset uses 4-bit IRQ register for internal interrupt routing, and therefore cannot handle IRQ numbers assigned to its devices. The patch corrects this problem by allowing PCI IRQs below 16. Cc: len.brown@intel.com Signed-off by: Natalie Protasevich Signed-off-by: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/mpparse.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'arch/i386/kernel/mpparse.c') diff --git a/arch/i386/kernel/mpparse.c b/arch/i386/kernel/mpparse.c index 34d21e2..6b1392d 100644 --- a/arch/i386/kernel/mpparse.c +++ b/arch/i386/kernel/mpparse.c @@ -1130,7 +1130,17 @@ int mp_register_gsi (u32 gsi, int triggering, int polarity) */ int irq = gsi; if (gsi < MAX_GSI_NUM) { - if (gsi > 15) + /* + * Retain the VIA chipset work-around (gsi > 15), but + * avoid a problem where the 8254 timer (IRQ0) is setup + * via an override (so it's not on pin 0 of the ioapic), + * and at the same time, the pin 0 interrupt is a PCI + * type. The gsi > 15 test could cause these two pins + * to be shared as IRQ0, and they are not shareable. + * So test for this condition, and if necessary, avoid + * the pin collision. + */ + if (gsi > 15 || (gsi == 0 && !timer_uses_ioapic_pin_0)) gsi = pci_irq++; /* * Don't assign IRQ used by ACPI SCI -- cgit v1.1