diff --git a/drivers/ide/atiixp.c b/drivers/ide/atiixp.c
index b2735d28f5cc..ecd1e62ca91a 100644
--- a/drivers/ide/atiixp.c
+++ b/drivers/ide/atiixp.c
@@ -52,7 +52,7 @@ static void atiixp_set_pio_mode(ide_drive_t *drive, const u8 pio)
 {
 	struct pci_dev *dev = to_pci_dev(drive->hwif->dev);
 	unsigned long flags;
-	int timing_shift = (drive->dn & 2) ? 16 : 0 + (drive->dn & 1) ? 0 : 8;
+	int timing_shift = (drive->dn ^ 1) * 8;
 	u32 pio_timing_data;
 	u16 pio_mode_data;
 
@@ -85,7 +85,7 @@ static void atiixp_set_dma_mode(ide_drive_t *drive, const u8 speed)
 {
 	struct pci_dev *dev = to_pci_dev(drive->hwif->dev);
 	unsigned long flags;
-	int timing_shift = (drive->dn & 2) ? 16 : 0 + (drive->dn & 1) ? 0 : 8;
+	int timing_shift = (drive->dn ^ 1) * 8;
 	u32 tmp32;
 	u16 tmp16;
 	u16 udma_ctl = 0;