diff --git a/drivers/ata/pata_legacy.c b/drivers/ata/pata_legacy.c
index 0a8bf09a5c19..03c580625c2c 100644
--- a/drivers/ata/pata_legacy.c
+++ b/drivers/ata/pata_legacy.c
@@ -315,9 +315,10 @@ static void pdc20230_set_piomode(struct ata_port *ap, struct ata_device *adev)
 	outb(inb(0x1F4) & 0x07, 0x1F4);
 
 	rt = inb(0x1F3);
-	rt &= 0x07 << (3 * adev->devno);
+	rt &= ~(0x07 << (3 * !adev->devno));
 	if (pio)
-		rt |= (1 + 3 * pio) << (3 * adev->devno);
+		rt |= (1 + 3 * pio) << (3 * !adev->devno);
+	outb(rt, 0x1F3);
 
 	udelay(100);
 	outb(inb(0x1F2) | 0x01, 0x1F2);