audio: host-zephyr: add HOST_DMA_IPC_POSITION_UPDATES Kconfig

Add a built option HOST_DMA_IPC_POSITION_UPDATES to control whether
functionality to send IPC stream position updates is enabled or
not. Most platforms provide more efficient means for host to
monitor DMA state, so this code is in most cases unncessary.

The current IPC sending code (from audio context) also assume
kernel context, so making this functionality user-space compatible
will require extra work.

Enable DMA IPC position updates by default for IPC3 as the feature can
be controlled by host with sof_ipc_stream_params.no_stream_position IPC
interface. Disable the feature by default for IPC4, as there is no host
IPC interface to control this and copier_update_params() unconditionally
disables IPC updates for IPC4 now, so this code is never used.

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>

Author: kv2019i

src/audio/Kconfig

@@ -42,6 +42,14 @@ config HOST_DMA_STREAM_SYNCHRONIZATION
 	  for each group, different than the default one determined by the system tick frequency.
 	  This feature will allow host lower power consumption in scenarios with deep buffering.
 
+config HOST_DMA_IPC_POSITION_UPDATES
+	bool "Support for stream position updates via IPC messages"
+	default y if IPC_MAJOR_3
+	help
+	  Support firmware functionality to report stream position updates
+	  by sending an IPC message whenever one period of audio is transferred.
+	  Most platforms provide more efficient ways to query the DMA status.
+
 config COMP_CHAIN_DMA
 	  bool "Chain DMA component"
 	  depends on IPC_MAJOR_4

src/audio/copier/host_copier.h

@@ -106,7 +106,9 @@ struct host_data {
 
 	/* stream info */
 	struct sof_ipc_stream_posn posn; /* TODO: update this */
+#if CONFIG_HOST_DMA_IPC_POSITION_UPDATES
 	struct ipc_msg *msg;	/**< host notification */
+#endif
 #if CONFIG_XRUN_NOTIFICATIONS_ENABLE
 	bool xrun_notification_sent;
 #endif

src/audio/host-zephyr.c

@@ -246,7 +246,9 @@ void host_common_update(struct host_data *hd, struct comp_dev *dev, uint32_t byt
 	struct comp_buffer *sink;
 	int ret;
 	bool update_mailbox = false;
+#if CONFIG_HOST_DMA_IPC_POSITION_UPDATES
 	bool send_ipc = false;
+#endif
 
 	if (dev->direction == SOF_IPC_STREAM_PLAYBACK) {
 		source = hd->dma_buffer;
@@ -285,6 +287,7 @@ void host_common_update(struct host_data *hd, struct comp_dev *dev, uint32_t byt
 	if (hd->cont_update_posn)
 		update_mailbox = true;
 
+#if CONFIG_HOST_DMA_IPC_POSITION_UPDATES
 	/* Don't send stream position if no_stream_position == 1 */
 	if (!hd->no_stream_position) {
 		hd->report_pos += bytes;
@@ -304,13 +307,16 @@ void host_common_update(struct host_data *hd, struct comp_dev *dev, uint32_t byt
 			send_ipc = true;
 		}
 	}
+#endif
 
 	if (update_mailbox) {
 		pipeline_get_timestamp(dev->pipeline, dev, &hd->posn);
 		mailbox_stream_write(dev->pipeline->posn_offset,
 				     &hd->posn, sizeof(hd->posn));
+#if CONFIG_HOST_DMA_IPC_POSITION_UPDATES
 		if (send_ipc)
 			ipc_msg_send(hd->msg, &hd->posn, false);
+#endif
 	}
 }
 
@@ -720,14 +726,16 @@ __cold int host_common_new(struct host_data *hd, struct comp_dev *dev,
 	dma_sg_init(&hd->local.elem_array);
 
 	ipc_build_stream_posn(&hd->posn, SOF_IPC_STREAM_POSITION, config_id);
+	hd->chan_index = -EINVAL;
 
+#if CONFIG_HOST_DMA_IPC_POSITION_UPDATES
 	hd->msg = ipc_msg_init(hd->posn.rhdr.hdr.cmd, sizeof(hd->posn));
 	if (!hd->msg) {
 		comp_err(dev, "ipc_msg_init failed");
 		sof_dma_put(hd->dma);
 		return -ENOMEM;
 	}
-	hd->chan_index = -EINVAL;
+#endif
 	hd->copy_type = COMP_COPY_NORMAL;
 
 #ifdef CONFIG_SOF_USERSPACE_LL
@@ -808,7 +816,9 @@ __cold void host_common_free(struct host_data *hd)
 
 	sof_dma_put(hd->dma);
 
+#if CONFIG_HOST_DMA_IPC_POSITION_UPDATES
 	ipc_msg_free(hd->msg);
+#endif
 	dma_sg_free(hd->alloc_ctx.heap, &hd->config.elem_array);
 }