The MMIO access implementation in the SIL680 driver is broken for
anything else but the Cell processor. Also, on IXP4xx the driver
tries MMIO but fails. Revert MMIO, like upstream for 2.6.26:

http://patchwork.ozlabs.org/linuxppc/patch?id=17772

Signed-off-by: Leon Woestenberg <leonw@mailcan.com>

Index: linux-2.6.24/drivers/ata/pata_sil680.c
===================================================================
--- linux-2.6.24.orig/drivers/ata/pata_sil680.c	2008-05-12 02:27:42.000000000 +0200
+++ linux-2.6.24/drivers/ata/pata_sil680.c	2008-05-12 02:29:04.000000000 +0200
@@ -269,7 +269,10 @@
 	dev_dbg(&pdev->dev, "sil680: BA5_EN = %d clock = %02X\n",
 		tmpbyte & 1, tmpbyte & 0x30);
 
-	*try_mmio = (tmpbyte & 1) || pci_resource_start(pdev, 5);
+#ifdef CONFIG_PPC_MERGE
+       if (machine_is(cell))
+               *try_mmio = (tmpbyte & 1) || pci_resource_start(pdev, 5);
+#endif
 
 	switch(tmpbyte & 0x30) {
 		case 0x00: