via82cxxx: fix UDMA settings programming

[~andy/linux] / drivers / ide / via82cxxx.c

diff --git a/drivers/ide/via82cxxx.c b/drivers/ide/via82cxxx.c
index 3db35b0142dce9c98642af812665eb91ad495e95..fbecf8ea820772ab5b87fefabed13742e8c01d66 100644 (file)
--- a/drivers/ide/via82cxxx.c
+++ b/drivers/ide/via82cxxx.c
@@ -146,10 +146,25 @@ static void via_set_speed(ide_hwif_t *hwif, u8 dn, struct ide_timing *timing)
        case ATA_UDMA4: t = timing->udma ? (0xe8 | (clamp_val(timing->udma, 2, 9) - 2)) : 0x0f; break;
        case ATA_UDMA5: t = timing->udma ? (0xe0 | (clamp_val(timing->udma, 2, 9) - 2)) : 0x07; break;
        case ATA_UDMA6: t = timing->udma ? (0xe0 | (clamp_val(timing->udma, 2, 9) - 2)) : 0x07; break;
-       default: return;
        }
 
-       pci_write_config_byte(dev, VIA_UDMA_TIMING + (3 - dn), t);
+       /* Set UDMA unless device is not UDMA capable */
+       if (vdev->via_config->udma_mask) {
+               u8 udma_etc;
+
+               pci_read_config_byte(dev, VIA_UDMA_TIMING + 3 - dn, &udma_etc);
+
+               /* clear transfer mode bit */
+               udma_etc &= ~0x20;
+
+               if (timing->udma) {
+                       /* preserve 80-wire cable detection bit */
+                       udma_etc &= 0x10;
+                       udma_etc |= t;
+               }
+
+               pci_write_config_byte(dev, VIA_UDMA_TIMING + 3 - dn, udma_etc);
+       }
 }
 
 /**