diff --git a/drivers/ata/pata_sis.c b/drivers/ata/pata_sis.c
index 2bd7645f1a88..cce2834b2b60 100644
--- a/drivers/ata/pata_sis.c
+++ b/drivers/ata/pata_sis.c
@@ -375,8 +375,9 @@ static void sis_66_set_dmamode (struct ata_port *ap, struct ata_device *adev)
 	int drive_pci = sis_old_port_base(adev);
 	u16 timing;
 
+	/* MWDMA 0-2 and UDMA 0-5 */
 	const u16 mwdma_bits[] = { 0x008, 0x302, 0x301 };
-	const u16 udma_bits[]  = { 0xF000, 0xD000, 0xB000, 0xA000, 0x9000};
+	const u16 udma_bits[]  = { 0xF000, 0xD000, 0xB000, 0xA000, 0x9000, 0x8000 };
 
 	pci_read_config_word(pdev, drive_pci, &timing);
 
diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
index ef83e6b1e314..233e88693395 100644
--- a/drivers/ata/sata_sil24.c
+++ b/drivers/ata/sata_sil24.c
@@ -888,6 +888,16 @@ static inline void sil24_host_intr(struct ata_port *ap)
 	u32 slot_stat, qc_active;
 	int rc;
 
+	/* If PCIX_IRQ_WOC, there's an inherent race window between
+	 * clearing IRQ pending status and reading PORT_SLOT_STAT
+	 * which may cause spurious interrupts afterwards.  This is
+	 * unavoidable and much better than losing interrupts which
+	 * happens if IRQ pending is cleared after reading
+	 * PORT_SLOT_STAT.
+	 */
+	if (ap->flags & SIL24_FLAG_PCIX_IRQ_WOC)
+		writel(PORT_IRQ_COMPLETE, port + PORT_IRQ_STAT);
+
 	slot_stat = readl(port + PORT_SLOT_STAT);
 
 	if (unlikely(slot_stat & HOST_SSTAT_ATTN)) {
@@ -895,9 +905,6 @@ static inline void sil24_host_intr(struct ata_port *ap)
 		return;
 	}
 
-	if (ap->flags & SIL24_FLAG_PCIX_IRQ_WOC)
-		writel(PORT_IRQ_COMPLETE, port + PORT_IRQ_STAT);
-
 	qc_active = slot_stat & ~HOST_SSTAT_ATTN;
 	rc = ata_qc_complete_multiple(ap, qc_active, sil24_finish_qc);
 	if (rc > 0)
@@ -910,7 +917,8 @@ static inline void sil24_host_intr(struct ata_port *ap)
 		return;
 	}
 
-	if (ata_ratelimit())
+	/* spurious interrupts are expected if PCIX_IRQ_WOC */
+	if (!(ap->flags & SIL24_FLAG_PCIX_IRQ_WOC) && ata_ratelimit())
 		ata_port_printk(ap, KERN_INFO, "spurious interrupt "
 			"(slot_stat 0x%x active_tag %d sactive 0x%x)\n",
 			slot_stat, ap->active_tag, ap->sactive);