ALSA: hda: make snd_hdac_stream_clear() static

This helper has no users outside of hdac_stream.c. External users
should only use snd_hdac_stream_start() and snd_hdac_stream_stop().

No functional change beyond making the function static and removing
the symbol export.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20220919121041.43463-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/hdaudio.h

@@ -561,7 +561,6 @@ int snd_hdac_stream_setup_periods(struct hdac_stream *azx_dev);
 int snd_hdac_stream_set_params(struct hdac_stream *azx_dev,
 				unsigned int format_val);
 void snd_hdac_stream_start(struct hdac_stream *azx_dev, bool fresh_start);
-void snd_hdac_stream_clear(struct hdac_stream *azx_dev);
 void snd_hdac_stream_stop(struct hdac_stream *azx_dev);
 void snd_hdac_stop_streams_and_chip(struct hdac_bus *bus);
 void snd_hdac_stream_reset(struct hdac_stream *azx_dev);

sound/hda/hdac_stream.c

@@ -112,10 +112,10 @@ void snd_hdac_stream_start(struct hdac_stream *azx_dev, bool fresh_start)
 EXPORT_SYMBOL_GPL(snd_hdac_stream_start);
 
 /**
- * snd_hdac_stream_clear - stop a stream DMA
+ * snd_hdac_stream_clear - helper to clear stream registers and stop DMA transfers
  * @azx_dev: HD-audio core stream to stop
  */
-void snd_hdac_stream_clear(struct hdac_stream *azx_dev)
+static void snd_hdac_stream_clear(struct hdac_stream *azx_dev)
 {
 	snd_hdac_stream_updateb(azx_dev, SD_CTL,
 				SD_CTL_DMA_START | SD_INT_MASK, 0);
@@ -124,7 +124,6 @@ void snd_hdac_stream_clear(struct hdac_stream *azx_dev)
 		snd_hdac_stream_updateb(azx_dev, SD_CTL_3B, SD_CTL_STRIPE_MASK, 0);
 	azx_dev->running = false;
 }
-EXPORT_SYMBOL_GPL(snd_hdac_stream_clear);
 
 /**
  * snd_hdac_stream_stop - stop a stream