fixup: audio: sink_api: add sink_get_state() and use it in mux

The mux module queried the state of its downstream consumers via the
legacy comp_buffer_get_from_sink() wrapper followed by
comp_buffer_get_sink_state(). This couples the module to the underlying
buffer implementation, which the sink/source API is meant to hide.

Signed-off-by: Piotr Hoppe <piotr.hoppe@intel.com>

Author: piotrhoppeintel

src/audio/buffers/comp_buffer.c

@@ -100,6 +100,13 @@ static int comp_buffer_commit_buffer(struct sof_sink *sink, size_t commit_size)
 	return 0;
 }
 
+static int comp_buffer_sink_get_state(struct sof_sink *sink)
+{
+	struct comp_buffer *buffer = comp_buffer_get_from_sink(sink);
+
+	return comp_get_state(comp_buffer_get_sink_component(buffer));
+}
+
 static int comp_buffer_set_ipc_params(struct sof_audio_buffer *audio_buffer,
 				      struct sof_ipc_stream_params *params,
 				      bool force_update)
@@ -189,6 +196,7 @@ APP_TASK_DATA static const struct sink_ops comp_buffer_sink_ops = {
 	.on_audio_format_set = audio_buffer_sink_on_audio_format_set,
 	.set_alignment_constants = audio_buffer_sink_set_alignment_constants,
 	.get_lft = audio_buffer_sink_get_lft,
+	.get_state = comp_buffer_sink_get_state,
 };
 
 static const struct audio_buffer_ops audio_buffer_ops = {

src/audio/mux/mux.c

@@ -251,9 +251,7 @@ static int demux_process(struct processing_module *mod,
 	 */
 	frames = source_get_data_frames_available(source);
 	for (i = 0; i < num_of_sinks; i++) {
-		struct comp_buffer *sink_buf = comp_buffer_get_from_sink(sinks[i]);
-
-		if (comp_buffer_get_sink_state(sink_buf) != dev->state)
+		if (sink_get_state(sinks[i]) != dev->state)
 			continue;
 
 		frames = MIN(frames, sink_get_free_frames(sinks[i]));
@@ -274,12 +272,11 @@ static int demux_process(struct processing_module *mod,
 	/* produce output, one sink at a time */
 	for (i = 0; i < num_of_sinks; i++) {
 		struct sof_sink *sink = sinks[i];
-		struct comp_buffer *sink_buf = comp_buffer_get_from_sink(sink);
-		uint32_t pipeline_id = buffer_pipeline_id(sink_buf);
+		uint32_t pipeline_id = sink_get_pipeline_id(sink);
 		struct mux_look_up *look_up;
 
 		/* skip sinks that are not in the same state as the component */
-		if (comp_buffer_get_sink_state(sink_buf) != dev->state)
+		if (sink_get_state(sink) != dev->state)
 			continue;
 
 		/* return if configuration for this pipeline is missing */

src/include/module/audio/sink_api.h

@@ -83,6 +83,13 @@ struct sink_ops {
 	 */
 	uint32_t (*get_lft)(struct sof_sink *sink);
 
+	/**
+	 * OPTIONAL: get the state of the component consuming data from this sink
+	 *
+	 * see comment of sink_get_state()
+	 */
+	int (*get_state)(struct sof_sink *sink);
+
 	/**
 	 * OPTIONAL: Notification to the sink implementation about changes in audio format
 	 *
@@ -318,6 +325,25 @@ static inline uint32_t sink_get_pipeline_id(struct sof_sink *sink)
 	return sink->audio_stream_params->pipeline_id;
 }
 
+/**
+ * @brief get the state of the component consuming data from this sink
+ *
+ * This allows a data producer to query the state of its downstream consumer
+ * without reaching into the underlying buffer implementation.
+ *
+ * @param sink a sink to be checked
+ *
+ * @return state of the consuming component, or COMP_STATE_NOT_EXIST (0) if there
+ *         is no connected consumer or the sink implementation does not track it
+ */
+static inline int sink_get_state(struct sof_sink *sink)
+{
+	if (!sink->ops->get_state)
+		return 0; /* COMP_STATE_NOT_EXIST */
+
+	return sink->ops->get_state(sink);
+}
+
 /**
  * @brief hook to be called when a module connects to the API
  *