pipeline: Add XRUN state and handler within pipeline.

Add an XRUN handler to notify components that an XRUN has occurred and
to take any remedial action. The pipeline itself will handle an XRUN by
re-preparing the components and then send start again from the pipeline
source component.

Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

src/audio/component.c

@@ -141,6 +141,7 @@ int comp_set_state(struct comp_dev *dev, int cmd)
 		}
 		break;
 	case COMP_CMD_STOP:
+	case COMP_CMD_XRUN:
 		if (dev->state == COMP_STATE_ACTIVE) {
 			dev->state = COMP_STATE_PREPARE;
 		} else {

src/audio/pipeline.c

@@ -76,6 +76,9 @@ static void connect_upstream(struct pipeline *p, struct comp_dev *start,
 	/* we are an endpoint if we have 0 source components */
 	if (list_is_empty(&current->bsource_list)) {
 		current->is_endpoint = 1;
+
+		/* pipeline source comp is current */
+		p->source_comp = current;
 		return;
 	}
 
@@ -86,8 +89,13 @@ static void connect_upstream(struct pipeline *p, struct comp_dev *start,
 		buffer = container_of(clist, struct comp_buffer, sink_list);
 
 		/* don't go upstream if this source is from another pipeline */
-		if (buffer->source->comp.pipeline_id != p->ipc_pipe.pipeline_id)
+		if (buffer->source->comp.pipeline_id != p->ipc_pipe.pipeline_id) {
+
+			/* pipeline source comp is current unless we go upstream */
+			p->source_comp = current;
+
 			continue;
+		}
 
 		connect_upstream(p, start, buffer->source);
 	}
@@ -210,6 +218,7 @@ static void pipeline_cmd_update(struct pipeline *p, struct comp_dev *comp,
 		break;
 	case COMP_CMD_SUSPEND:
 	case COMP_CMD_RESUME:
+	case COMP_CMD_XRUN:
 	default:
 		break;
 	}
@@ -1001,6 +1010,38 @@ void pipeline_xrun(struct pipeline *p, struct comp_dev *dev,
 	}
 }
 
+/* recover the pipeline from a XRUN condition */
+static int pipeline_xrun_recover(struct pipeline *p)
+{
+	int ret;
+
+	trace_pipe_error("pxr");
+
+	/* notify all pipeline comps we are in XRUN */
+	ret = pipeline_cmd(p, p->source_comp, COMP_CMD_XRUN, NULL);
+	if (ret < 0) {
+		trace_pipe_error("px0");
+		return ret;
+	}
+	p->xrun_bytes = 0;
+
+	/* prepare the pipeline */
+	pipeline_prepare(p, p->source_comp);
+	if (ret < 0) {
+		trace_pipe_error("px1");
+		return ret;
+	}
+
+	/* restart pipeline comps */
+	pipeline_cmd(p, p->source_comp, COMP_CMD_START, NULL);
+	if (ret < 0) {
+		trace_pipe_error("px2");
+		return ret;
+	}
+
+	return 0;
+}
+
 /* notify pipeline that this component requires buffers emptied/filled */
 void pipeline_schedule_copy(struct pipeline *p, uint64_t start)
 {
@@ -1025,13 +1066,36 @@ static void pipeline_task(void *arg)
 {
 	struct pipeline *p = arg;
 	struct comp_dev *dev = p->sched_comp;
+	int err;
 
 	tracev_pipe("PWs");
 
-	/* copy data from upstream source endpoints to downstream endpoints */
-	pipeline_copy_from_upstream(dev, dev);
-	pipeline_copy_to_downstream(dev, dev);
+	/* are we in xrun ? */
+	if (p->xrun_bytes) {
+		err = pipeline_xrun_recover(p);
+		if (err < 0)
+			return;  /* failed - host will stop this pipeline */
+		goto sched;
+	}
 
+	/* copy data from upstream source endpoints to downstream endpoints */
+	err = pipeline_copy_from_upstream(dev, dev);
+	if (err < 0) {
+		err = pipeline_xrun_recover(p);
+		if (err < 0)
+			return;  /* failed - host will stop this pipeline */
+		goto sched;
+	}
+
+	err = pipeline_copy_to_downstream(dev, dev);
+	if (err < 0) {
+		err = pipeline_xrun_recover(p);
+		if (err < 0)
+			return;  /* failed - host will stop this pipeline */
+		goto sched;
+	}
+
+sched:
 	tracev_pipe("PWe");
 
 	/* now reschedule the task */

src/include/reef/audio/component.h

@@ -80,6 +80,7 @@
 #define COMP_CMD_RESUME		6	/* resume component */
 #define COMP_CMD_RESET		6	/* reset component */
 #define COMP_CMD_PREPARE	7	/* prepare component */
+#define COMP_CMD_XRUN		8	/* XRUN component */
 
 /*
  * standard component control commands

src/include/reef/audio/pipeline.h

@@ -67,7 +67,8 @@ struct pipeline {
 
 	/* scheduling */
 	struct task pipe_task;		/* pipeline processing task */
-	struct comp_dev *sched_comp;
+	struct comp_dev *sched_comp;	/* component that drives scheduling in this pipe */
+	struct comp_dev *source_comp;	/* source component for this pipe */
 };
 
 /* static pipeline */