Index: linux-2.6.21/drivers/net/wireless/hostap/hostap_hw.c
===================================================================
--- linux-2.6.21.orig/drivers/net/wireless/hostap/hostap_hw.c	2007-07-07 12:45:39.000000000 +0100
+++ linux-2.6.21/drivers/net/wireless/hostap/hostap_hw.c	2007-07-07 12:47:30.000000000 +0100
@@ -2666,6 +2666,12 @@
 	iface = netdev_priv(dev);
 	local = iface->local;
 
+	if(dev->base_addr == 0)
+	{
+		printk(KERN_DEBUG "%s: IRQ before base_addr set\n", dev->name);
+		return IRQ_HANDLED;
+	}
+
 	prism2_io_debug_add(dev, PRISM2_IO_DEBUG_CMD_INTERRUPT, 0, 0);
 
 	if (local->func->card_present && !local->func->card_present(local)) {