diff --git a/target/linux/brcm-2.6/patches/001-bcm947xx.patch b/target/linux/brcm-2.6/patches/001-bcm947xx.patch
index 786b9af788..864f7747de 100644
--- a/target/linux/brcm-2.6/patches/001-bcm947xx.patch
+++ b/target/linux/brcm-2.6/patches/001-bcm947xx.patch
@@ -11243,7 +11243,7 @@ diff -urN linux.old/arch/mips/bcm947xx/Makefile linux.dev/arch/mips/bcm947xx/Mak
 diff -urN linux.old/arch/mips/bcm947xx/pci.c linux.dev/arch/mips/bcm947xx/pci.c
 --- linux.old/arch/mips/bcm947xx/pci.c	1970-01-01 01:00:00.000000000 +0100
 +++ linux.dev/arch/mips/bcm947xx/pci.c	2006-10-15 23:29:14.000000000 +0200
-@@ -0,0 +1,215 @@
+@@ -0,0 +1,227 @@
 +#include <linux/kernel.h>
 +#include <linux/init.h>
 +#include <linux/pci.h>
@@ -11356,11 +11356,23 @@ diff -urN linux.old/arch/mips/bcm947xx/pci.c linux.dev/arch/mips/bcm947xx/pci.c
 +
 +int __init pcibios_map_irq(struct pci_dev *dev, u8 slot, u8 pin)
 +{
++	unsigned long flags;
 +	u8 irq;
++	uint idx;
 +	
-+	if (dev->bus->number == 1)
-+		return 2;
-+
++	/* external: use the irq of the pci core */
++	if (dev->bus->number >= 1) {
++		spin_lock_irqsave(&sbh_lock, flags);
++		idx = sb_coreidx(sbh);
++		sb_setcore(sbh, SB_PCI, 0);
++		irq = sb_irq(sbh);
++		sb_setcoreidx(sbh, idx);
++		spin_unlock_irqrestore(&sbh_lock, flags);
++		
++		return irq + 2;
++	}
++	
++	/* internal */
 +	pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &irq);
 +	return irq + 2;
 +}