diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 3cc7096cfda758e9b3ffd514aaf6e70928ec7f8d..f46fbd3bd3fb6b4456032a0255bad894e8fc9cdb 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2942,6 +2942,10 @@ const struct ata_timing *ata_timing_find_mode(u8 xfer_mode)
 
 	if (xfer_mode == t->mode)
 		return t;
+
+	WARN_ONCE(true, "%s: unable to find timing for xfer_mode 0x%x\n",
+			__func__, xfer_mode);
+
 	return NULL;
 }