diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index c75c0d1..cdca2ab 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -1075,7 +1075,8 @@
 const char *snd_pcm_format_name(snd_pcm_format_t format);
 
 /**
- * Get a string naming the direction of a stream
+ * snd_pcm_stream_str - Get a string naming the direction of a stream
+ * @substream: the pcm substream instance
  */
 static inline const char *snd_pcm_stream_str(struct snd_pcm_substream *substream)
 {