1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/ata/pata_via.c b/drivers/ata/pata_via.c
index 78eac276effb..0d97890af681 100644
--- a/drivers/ata/pata_via.c
+++ b/drivers/ata/pata_via.c
@@ -303,14 +303,21 @@ static void via_do_set_mode(struct ata_port *ap, struct ata_device *adev, int mo
         }
 
         /* Set UDMA unless device is not UDMA capable */
-        if (udma_type && t.udma) {
-                u8 cable80_status;
+        if (udma_type) {
+                u8 udma_etc;
 
-                /* Get 80-wire cable detection bit */
-                pci_read_config_byte(pdev, 0x50 + offset, &cable80_status);
-                cable80_status &= 0x10;
+                pci_read_config_byte(pdev, 0x50 + offset, &udma_etc);
 
-                pci_write_config_byte(pdev, 0x50 + offset, ut | cable80_status);
+                /* clear transfer mode bit */
+                udma_etc &= ~0x20;
+
+                if (t.udma) {
+                        /* preserve 80-wire cable detection bit */
+                        udma_etc &= 0x10;
+                        udma_etc |= ut;
+                }
+
+                pci_write_config_byte(pdev, 0x50 + offset, udma_etc);
         }
 }