[RFC]: Add support for drain operation

src/audio/pipeline/pipeline-schedule.c

@@ -19,6 +19,7 @@
 #include <ipc/header.h>
 #include <ipc/stream.h>
 #include <ipc/topology.h>
+#include <sof/ipc/common.h>
 #include <errno.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -201,6 +202,25 @@ static enum task_state pipeline_task(void *arg)
 	 * copying below.
 	 */
 	err = pipeline_copy(p);
+	if (p->status == COMP_STATE_DRAINING) {
+		/* check the return value of the copy operation.
+		 *
+		 * if it's <= 0 then the draining opearation is over
+		 * and we need to send a notification to the host
+		 */
+		if (err <= 0) {
+			/* set pipeline status back to ACTIVE */
+			p->status = COMP_STATE_ACTIVE;
+
+			/* notify host that draining is over */
+			err = ipc_stream_drain_notify();
+
+			if (err < 0) {
+				pipe_err(p, "pipeline_task(): failed drain notify");
+				return SOF_TASK_STATE_COMPLETED;
+			}
+		}
+	}
 	if (err < 0) {
 		/* try to recover */
 		err = pipeline_xrun_recover(p);
@@ -320,6 +340,13 @@ void pipeline_schedule_triggered(struct pipeline_walk_context *ctx,
 				 */
 				p->xrun_bytes = 1;
 		}
+		break;
+	case COMP_TRIGGER_DRAIN:
+		list_for_item(tlist, &ctx->pipelines) {
+			p = container_of(tlist, struct pipeline, list);
+			p->xrun_bytes = 0;
+			p->status = COMP_STATE_DRAINING;
+		}
 	}
 
 	irq_local_enable(flags);

src/audio/pipeline/pipeline-stream.c

@@ -328,6 +328,7 @@ static int pipeline_comp_trigger(struct comp_dev *current,
 	case COMP_TRIGGER_STOP:
 	case COMP_TRIGGER_RELEASE:
 	case COMP_TRIGGER_START:
+	case COMP_TRIGGER_DRAIN:
 		break;
 	}
 
@@ -349,14 +350,21 @@ static int pipeline_comp_trigger(struct comp_dev *current,
 
 	current->pipeline->trigger.pending = false;
 
-	/* send command to the component and update pipeline state */
-	err = comp_trigger(current, ppl_data->cmd);
-	if (err < 0)
-		return err;
+	/* send command to the component and update pipeline state.
+	 *
+	 * if we're dealing with DRAIN trigger we don't want to update
+	 * the state of the components since we're not using that
+	 * information
+	 */
+	if (ppl_data->cmd != COMP_TRIGGER_DRAIN) {
+		err = comp_trigger(current, ppl_data->cmd);
+		if (err < 0)
+			return err;
 
-	if (err == PPL_STATUS_PATH_STOP) {
-		current->pipeline->trigger.aborted = true;
-		return err;
+		if (err == PPL_STATUS_PATH_STOP) {
+			current->pipeline->trigger.aborted = true;
+			return err;
+		}
 	}
 
 	switch (ppl_data->cmd) {

src/include/ipc/stream.h

@@ -158,4 +158,9 @@ struct sof_ipc_stream_posn {
 	int32_t xrun_size;	/**< XRUN size in bytes */
 } __attribute__((packed, aligned(4)));
 
+/* drain information */
+struct sof_ipc_stream_drain {
+	struct sof_ipc_reply rhdr;
+} __attribute__((packed, aligned(4)));
+
 #endif /* __IPC_STREAM_H__ */

src/include/sof/audio/component.h

@@ -65,6 +65,7 @@ struct timestamp_data;
 #define COMP_STATE_PAUSED	4	/**< Component paused */
 #define COMP_STATE_ACTIVE	5	/**< Component active */
 #define COMP_STATE_PRE_ACTIVE	6	/**< Component after early initialisation */
+#define COMP_STATE_DRAINING	7	/**< Component draining */
 /** @}*/
 
 /** \name Standard Component Stream Commands
@@ -91,6 +92,7 @@ enum {
 	COMP_TRIGGER_POST_STOP,		/**< Finalize stop component stream */
 	COMP_TRIGGER_POST_PAUSE,	/**< Finalize pause component stream */
 	COMP_TRIGGER_NO_ACTION,		/**< No action required */
+	COMP_TRIGGER_DRAIN,		/**< Start drain operation */
 };
 /** @}*/
 

src/include/sof/ipc/common.h

@@ -197,4 +197,9 @@ void ipc_msg_reply(struct sof_ipc_reply *reply);
  */
 void ipc_complete_cmd(struct ipc *ipc);
 
+/**
+ * \brief Notify host that the drain operation is done.
+ */
+int ipc_stream_drain_notify(void);
+
 #endif /* __SOF_DRIVERS_IPC_H__ */

src/ipc/ipc3/handler.c

@@ -422,6 +422,51 @@ static int ipc_stream_position(uint32_t header)
 	return 1;
 }
 
+int ipc_stream_drain_notify(void)
+{
+	struct ipc *ipc = ipc_get();
+	struct sof_ipc_stream stream;
+	struct sof_ipc_stream_drain drain;
+	struct ipc_comp_dev *pcm_dev;
+
+	/* copy message with ABI safe method */
+	IPC_COPY_CMD(stream, ipc->comp_data);
+
+	/* get the pcm dev */
+	pcm_dev = ipc_get_comp_by_id(ipc, stream.comp_id);
+	if (!pcm_dev) {
+		tr_err(&ipc_tr, "ipc: comp %d not found", stream.comp_id);
+		return -ENODEV;
+	}
+
+	/* check core */
+	if (!cpu_is_me(pcm_dev->core))
+		return ipc_process_on_core(pcm_dev->core, false);
+
+	/* prepare message */
+	memset(&drain, 0, sizeof(drain));
+	drain.rhdr.hdr.cmd = SOF_IPC_GLB_STREAM_MSG | SOF_IPC_STREAM_TRIG_DRAIN |
+		stream.comp_id;
+	drain.rhdr.hdr.size = sizeof(drain);
+
+	if (!pcm_dev->cd->pipeline) {
+		tr_err(&ipc_tr, "ipc: comp %d pipeline not found",
+		       stream.comp_id);
+		return -EINVAL;
+	}
+
+	/* write message */
+	mailbox_stream_write(pcm_dev->cd->pipeline->posn_offset, &drain,
+			     sizeof(drain));
+
+	/* send IPC notification */
+	struct ipc_msg *msg = ipc_msg_init(drain.rhdr.hdr.cmd, drain.rhdr.hdr.size);
+
+	ipc_msg_send(msg, &drain, false);
+
+	return 0;
+}
+
 static int ipc_stream_trigger(uint32_t header)
 {
 	struct ipc *ipc = ipc_get();
@@ -461,6 +506,9 @@ static int ipc_stream_trigger(uint32_t header)
 	case SOF_IPC_STREAM_TRIG_RELEASE:
 		cmd = COMP_TRIGGER_PRE_RELEASE;
 		break;
+	case SOF_IPC_STREAM_TRIG_DRAIN:
+		cmd = COMP_TRIGGER_DRAIN;
+		break;
 	/* XRUN is special case- TODO */
 	case SOF_IPC_STREAM_TRIG_XRUN:
 		return 0;