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[PATCH] x86: avoid wasting IRQs patch update
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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.

Signed-off by: Natalie Protasevich <Natalie.Protasevich@unisys.com>

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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Natalie.Protasevich@unisys.com authored and Linus Torvalds committed Jul 29, 2005
1 parent 8062594 commit e1afc3f
Showing 1 changed file with 9 additions and 1 deletion.
10 changes: 9 additions & 1 deletion arch/i386/kernel/mpparse.c
Original file line number Diff line number Diff line change
Expand Up @@ -1116,7 +1116,15 @@ int mp_register_gsi (u32 gsi, int edge_level, int active_high_low)
*/
int irq = gsi;
if (gsi < MAX_GSI_NUM) {
gsi = pci_irq++;
if (gsi > 15)
gsi = pci_irq++;
#ifdef CONFIG_ACPI_BUS
/*
* Don't assign IRQ used by ACPI SCI
*/
if (gsi == acpi_fadt.sci_int)
gsi = pci_irq++;
#endif
gsi_to_irq[irq] = gsi;
} else {
printk(KERN_ERR "GSI %u is too high\n", gsi);
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