diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 23d1dc5faf73..eb8ff7b22616 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -898,7 +898,7 @@ EXPORT_SYMBOL_GPL(ata_xfer_mode2mask);
  *	RETURNS:
  *	Matching xfer_shift, -1 if no match found.
  */
-int ata_xfer_mode2shift(unsigned long xfer_mode)
+int ata_xfer_mode2shift(u8 xfer_mode)
 {
 	const struct ata_xfer_ent *ent;
 
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 16107122e587..732de9014626 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1110,7 +1110,7 @@ extern void ata_unpack_xfermask(unsigned long xfer_mask,
 			unsigned long *udma_mask);
 extern u8 ata_xfer_mask2mode(unsigned long xfer_mask);
 extern unsigned long ata_xfer_mode2mask(u8 xfer_mode);
-extern int ata_xfer_mode2shift(unsigned long xfer_mode);
+extern int ata_xfer_mode2shift(u8 xfer_mode);
 extern const char *ata_mode_string(unsigned long xfer_mask);
 extern unsigned long ata_id_xfermask(const u16 *id);
 extern int ata_std_qc_defer(struct ata_queued_cmd *qc);