diff -Nurp b/arch/powerpc/kernel/ibmebus.c a/arch/powerpc/kernel/ibmebus.c
--- b/arch/powerpc/kernel/ibmebus.c	2008-09-22 00:29:55.000000000 +0200
+++ a/arch/powerpc/kernel/ibmebus.c	2008-09-23 12:04:53.000000000 +0200
@@ -216,12 +216,16 @@ int ibmebus_request_irq(u32 ist, irq_han
 			unsigned long irq_flags, const char *devname,
 			void *dev_id)
 {
+	int ret;
 	unsigned int irq = irq_create_mapping(NULL, ist);
 
 	if (irq == NO_IRQ)
 		return -EINVAL;
 
-	return request_irq(irq, handler, irq_flags, devname, dev_id);
+	ret = request_irq(irq, handler, irq_flags, devname, dev_id);
+	set_irq_type(irq, IRQ_TYPE_EDGE_RISING);
+
+	return ret;
 }
 EXPORT_SYMBOL(ibmebus_request_irq);