ALSA: pcm: Add debug-print helper function

Adds a function getting the stream-name as a string for
a specific stream.
Signed-off-by: Ola Lilja <ola.o.lilja@stericsson.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

include/sound/pcm.h

@@ -1073,4 +1073,15 @@ static inline void snd_pcm_limit_isa_dma_size(int dma, size_t *max)
 
 const char *snd_pcm_format_name(snd_pcm_format_t format);
 
+/**
+ * Get a string naming the direction of a stream
+ */
+static inline const char *snd_pcm_stream_str(struct snd_pcm_substream *substream)
+{
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		return "Playback";
+	else
+		return "Capture";
+}
+
 #endif /* __SOUND_PCM_H */