Audio: MFCC: Add VAD switch control notification to user space

singalsu · singalsu · commit e5ac2e14d3a4 · 2026-05-21T11:00:52.000+03:00
Add IPC4 notification that sends the VAD state to user space via a
switch control whenever the VAD decision changes between speech and
silence. The notification is initialized during prepare and sent from
the audio processing path on VAD state transitions.

The implementation follows the TDFB/sound_dose notification pattern:
mfcc_ipc4.c contains the IPC4-specific notification init and send
functions, while mfcc.c provides weak stubs so IPC3 builds link
without the IPC4 dependencies.

Add handling for SOF_IPC4_SWITCH_CONTROL_PARAM_ID in mfcc_get_config
and mfcc_set_config so the kernel driver can read back the current VAD
state after receiving a notification. The switch control is read-only
from the DSP side.

Both the notification init and the VAD state change detection are
gated on the update_controls flag in the configuration blob struct.

Add a switch control (mixer) to the MFCC topology2 widget definition
for the VAD notification.

Signed-off-by: Seppo Ingalsuo &lt;seppo.ingalsuo@linux.intel.com&gt;
diff --git a/src/audio/mfcc/CMakeLists.txt b/src/audio/mfcc/CMakeLists.txt
@@ -5,4 +5,7 @@ if(CONFIG_COMP_MFCC STREQUAL "m" AND DEFINED CONFIG_LLEXT)
   add_dependencies(app mfcc)
 else()
   add_local_sources(sof mfcc.c mfcc_setup.c mfcc_common.c mfcc_generic.c mfcc_hifi4.c mfcc_hifi3.c mfcc_vad.c)
+  if(CONFIG_IPC_MAJOR_4)
+    add_local_sources(sof mfcc_ipc4.c)
+  endif()
 endif()
diff --git a/src/audio/mfcc/mfcc.c b/src/audio/mfcc/mfcc.c
@@ -97,36 +97,13 @@ static int mfcc_free(struct processing_module *mod)
 	struct mfcc_comp_data *cd = module_get_private_data(mod);
 
 	comp_info(mod->dev, "entry");
+	ipc_msg_free(cd->msg);
 	mod_data_blob_handler_free(mod, cd->model_handler);
 	mfcc_free_buffers(mod);
 	mod_free(mod, cd);
 	return 0;
 }
 
-static int mfcc_get_config(struct processing_module *mod,
-			   uint32_t config_id, uint32_t *data_offset_size,
-			   uint8_t *fragment, size_t fragment_size)
-{
-	struct sof_ipc_ctrl_data *cdata = (struct sof_ipc_ctrl_data *)fragment;
-	struct mfcc_comp_data *cd = module_get_private_data(mod);
-
-	comp_info(mod->dev, "entry");
-
-	return comp_data_blob_get_cmd(cd->model_handler, cdata, fragment_size);
-}
-
-static int mfcc_set_config(struct processing_module *mod, uint32_t config_id,
-			   enum module_cfg_fragment_position pos, uint32_t data_offset_size,
-			   const uint8_t *fragment, size_t fragment_size, uint8_t *response,
-			   size_t response_size)
-{
-	struct mfcc_comp_data *cd = module_get_private_data(mod);
-
-	comp_info(mod->dev, "entry");
-
-	return comp_data_blob_set(cd->model_handler, pos, data_offset_size,
-				  fragment, fragment_size);
-}
 
 static int mfcc_process(struct processing_module *mod,
 			struct input_stream_buffer *input_buffers, int num_input_buffers,
@@ -198,6 +175,15 @@ static int mfcc_prepare(struct processing_module *mod,
 		goto err;
 	}
 
+	/* Initialize VAD switch control notification if enabled */
+	if (cd->config && cd->config->update_controls) {
+		ret = mfcc_ipc_notification_init(mod);
+		if (ret < 0)
+			goto err;
+
+		cd->vad_prev = false;
+	}
+
 	return 0;
 
 err:
diff --git a/src/audio/mfcc/mfcc_common.c b/src/audio/mfcc/mfcc_common.c
@@ -29,8 +29,9 @@ LOG_MODULE_REGISTER(mfcc_common, CONFIG_SOF_LOG_LEVEL);
  * The main processing function for MFCC
  */
 
-static int mfcc_stft_process(const struct comp_dev *dev, struct mfcc_comp_data *cd)
+static int mfcc_stft_process(struct processing_module *mod, struct mfcc_comp_data *cd)
 {
+	const struct comp_dev *dev = mod->dev;
 	struct sof_mfcc_config *config = cd->config;
 	struct mfcc_state *state = &cd->state;
 	struct mfcc_buffer *buf = &state->buf;
@@ -186,6 +187,16 @@ static int mfcc_stft_process(const struct comp_dev *dev, struct mfcc_comp_data *
 
 		/* Increment hop counter at end of hop processing */
 		state->hop_count++;
+
+		/* Send notification when VAD state changes */
+		if (config->update_controls) {
+			bool vad_now = cd->vad.is_speech;
+
+			if (vad_now != cd->vad_prev) {
+				mfcc_send_vad_notification(mod, vad_now ? 1 : 0);
+				cd->vad_prev = vad_now;
+			}
+		}
 	}
 
 	return cc_count;
@@ -294,7 +305,7 @@ void mfcc_s16_default(struct processing_module *mod, struct input_stream_buffer
 	mfcc_source_copy_s16(bsource, buf, &state->emph, frames, state->source_channel);
 
 	/* Run STFT and processing after FFT: Mel auditory filter and DCT. */
-	num_ceps = mfcc_stft_process(mod->dev, cd);
+	num_ceps = mfcc_stft_process(mod, cd);
 
 	/* If new output produced, set up pointer into scratch data and mark header pending */
 	if (num_ceps > 0) {
@@ -393,7 +404,7 @@ void mfcc_s24_default(struct processing_module *mod, struct input_stream_buffer
 	mfcc_source_copy_s24(bsource, buf, &state->emph, frames, state->source_channel);
 
 	/* Run STFT and processing after FFT */
-	num_ceps = mfcc_stft_process(mod->dev, cd);
+	num_ceps = mfcc_stft_process(mod, cd);
 
 	/* If new output produced, set up pointer into scratch data */
 	if (num_ceps > 0) {
@@ -472,7 +483,7 @@ void mfcc_s32_default(struct processing_module *mod, struct input_stream_buffer
 	mfcc_source_copy_s32(bsource, buf, &state->emph, frames, state->source_channel);
 
 	/* Run STFT and processing after FFT */
-	num_ceps = mfcc_stft_process(mod->dev, cd);
+	num_ceps = mfcc_stft_process(mod, cd);
 
 	/* If new output produced, set up pointer into scratch data */
 	if (num_ceps > 0) {
diff --git a/src/audio/mfcc/mfcc_ipc4.c b/src/audio/mfcc/mfcc_ipc4.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: BSD-3-Clause
+//
+// Copyright(c) 2026 Intel Corporation.
+//
+// Author: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
+
+/**
+ * \file mfcc_ipc4.c
+ * \brief IPC4-specific functions for MFCC component.
+ *
+ * Provides VAD switch control notification to user space via the
+ * IPC4 module notification mechanism.
+ */
+
+#include <sof/audio/mfcc/mfcc_comp.h>
+#include <sof/audio/module_adapter/module/generic.h>
+#include <sof/audio/component.h>
+#include <sof/ipc/msg.h>
+#include <sof/trace/trace.h>
+#include <ipc4/base-config.h>
+#include <ipc4/header.h>
+#include <ipc4/module.h>
+#include <ipc4/notification.h>
+#include <rtos/string.h>
+#include <errno.h>
+#include <stdint.h>
+
+LOG_MODULE_DECLARE(mfcc, CONFIG_SOF_LOG_LEVEL);
+
+/**
+ * \brief Initialize IPC notification message for VAD switch control.
+ *
+ * Allocates and configures the IPC message used to send VAD state
+ * change notifications to user space via a switch control.
+ */
+int mfcc_ipc_notification_init(struct processing_module *mod)
+{
+	struct mfcc_comp_data *cd = module_get_private_data(mod);
+	struct ipc_msg msg_proto;
+	struct comp_dev *dev = mod->dev;
+	struct comp_ipc_config *ipc_config = &dev->ipc_config;
+	union ipc4_notification_header *primary =
+		(union ipc4_notification_header *)&msg_proto.header;
+	struct sof_ipc4_notify_module_data *msg_module_data;
+	struct sof_ipc4_control_msg_payload *msg_payload;
+
+	memset_s(&msg_proto, sizeof(msg_proto), 0, sizeof(msg_proto));
+	primary->r.notif_type = SOF_IPC4_MODULE_NOTIFICATION;
+	primary->r.type = SOF_IPC4_GLB_NOTIFICATION;
+	primary->r.rsp = SOF_IPC4_MESSAGE_DIR_MSG_REQUEST;
+	primary->r.msg_tgt = SOF_IPC4_MESSAGE_TARGET_FW_GEN_MSG;
+	cd->msg = ipc_msg_w_ext_init(msg_proto.header, msg_proto.extension,
+				     sizeof(struct sof_ipc4_notify_module_data) +
+				     sizeof(struct sof_ipc4_control_msg_payload) +
+				     sizeof(struct sof_ipc4_ctrl_value_chan));
+	if (!cd->msg) {
+		comp_err(dev, "Failed to initialize VAD notification");
+		return -ENOMEM;
+	}
+
+	msg_module_data = (struct sof_ipc4_notify_module_data *)cd->msg->tx_data;
+	msg_module_data->instance_id = IPC4_INST_ID(ipc_config->id);
+	msg_module_data->module_id = IPC4_MOD_ID(ipc_config->id);
+	msg_module_data->event_id = SOF_IPC4_NOTIFY_MODULE_EVENTID_ALSA_MAGIC_VAL |
+		SOF_IPC4_SWITCH_CONTROL_PARAM_ID;
+	msg_module_data->event_data_size = sizeof(struct sof_ipc4_control_msg_payload) +
+		sizeof(struct sof_ipc4_ctrl_value_chan);
+
+	msg_payload = (struct sof_ipc4_control_msg_payload *)msg_module_data->event_data;
+	msg_payload->id = MFCC_CTRL_INDEX_VAD;
+	msg_payload->num_elems = 1;
+	msg_payload->chanv[0].channel = 0;
+
+	comp_dbg(dev, "VAD notification init: instance_id = 0x%08x, module_id = 0x%08x",
+		 msg_module_data->instance_id, msg_module_data->module_id);
+	return 0;
+}
+
+/**
+ * \brief Send VAD switch control notification to user space.
+ * \param mod Processing module.
+ * \param val VAD value: 1 = speech, 0 = silence.
+ */
+void mfcc_send_vad_notification(struct processing_module *mod, uint32_t val)
+{
+	struct mfcc_comp_data *cd = module_get_private_data(mod);
+	struct sof_ipc4_notify_module_data *msg_module_data;
+	struct sof_ipc4_control_msg_payload *msg_payload;
+
+	if (!cd->msg)
+		return;
+
+	msg_module_data = (struct sof_ipc4_notify_module_data *)cd->msg->tx_data;
+	msg_payload = (struct sof_ipc4_control_msg_payload *)msg_module_data->event_data;
+	msg_payload->chanv[0].value = val;
+	ipc_msg_send(cd->msg, NULL, false);
+}
+
+int mfcc_get_config(struct processing_module *mod,
+		    uint32_t config_id, uint32_t *data_offset_size,
+		    uint8_t *fragment, size_t fragment_size)
+{
+	struct sof_ipc_ctrl_data *cdata = (struct sof_ipc_ctrl_data *)fragment;
+	struct mfcc_comp_data *cd = module_get_private_data(mod);
+	struct sof_ipc4_control_msg_payload *ctl;
+
+	comp_info(mod->dev, "entry");
+
+	switch (config_id) {
+	case SOF_IPC4_SWITCH_CONTROL_PARAM_ID:
+		ctl = (struct sof_ipc4_control_msg_payload *)fragment;
+		if (ctl->id == MFCC_CTRL_INDEX_VAD && ctl->num_elems == 1) {
+			ctl->chanv[0].value = cd->vad_prev ? 1 : 0;
+			*data_offset_size = sizeof(*ctl) + sizeof(ctl->chanv[0]);
+			return 0;
+		}
+		return -EINVAL;
+	default:
+		return comp_data_blob_get_cmd(cd->model_handler, cdata, fragment_size);
+	}
+}
+
+int mfcc_set_config(struct processing_module *mod, uint32_t config_id,
+		    enum module_cfg_fragment_position pos, uint32_t data_offset_size,
+		    const uint8_t *fragment, size_t fragment_size, uint8_t *response,
+		    size_t response_size)
+{
+	struct mfcc_comp_data *cd = module_get_private_data(mod);
+
+	comp_info(mod->dev, "entry");
+
+	switch (config_id) {
+	case SOF_IPC4_SWITCH_CONTROL_PARAM_ID:
+		/* VAD switch is read-only, ignore set requests */
+		return 0;
+	default:
+		return comp_data_blob_set(cd->model_handler, pos, data_offset_size,
+					  fragment, fragment_size);
+	}
+}
diff --git a/src/include/sof/audio/mfcc/mfcc_comp.h b/src/include/sof/audio/mfcc/mfcc_comp.h
@@ -9,10 +9,12 @@
 #define __SOF_AUDIO_MFCC_MFCC_COMP_H__
 
 #include <sof/audio/module_adapter/module/generic.h>
+#include <sof/audio/data_blob.h>
 #include <sof/math/auditory.h>
 #include <sof/math/dct.h>
 #include <sof/math/fft.h>
 #include <sof/audio/mfcc/mfcc_vad.h>
+#include <sof/ipc/msg.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ -34,6 +36,9 @@
 #define MFCC_FFT_BITS	32
 #define MFCC_MAX_SAMPLE_RATE 64000 /* Max sample rate in Hz, limited by int16_t Mel scale */
 
+/** \brief Switch control index for VAD notification to user space */
+#define MFCC_CTRL_INDEX_VAD	0
+
 /**
  * \brief Data header prepended to every MFCC output frame.
  *
@@ -137,7 +142,9 @@ struct mfcc_comp_data {
 	struct mfcc_vad_state vad;
 	struct comp_data_blob_handler *model_handler;
 	struct sof_mfcc_config *config;
+	struct ipc_msg *msg;		/**< IPC notification for VAD switch control */
 	int max_frames;
+	bool vad_prev;			/**< Previous VAD state for edge detection */
 	mfcc_func mfcc_func;		/**< processing function */
 };
 
@@ -192,6 +199,52 @@ void mfcc_s32_default(struct processing_module *mod, struct input_stream_buffer
 		      struct output_stream_buffer *bsink, int frames);
 #endif
 
+#if CONFIG_IPC_MAJOR_4
+int mfcc_ipc_notification_init(struct processing_module *mod);
+
+void mfcc_send_vad_notification(struct processing_module *mod, uint32_t val);
+
+int mfcc_get_config(struct processing_module *mod,
+		    uint32_t config_id, uint32_t *data_offset_size,
+		    uint8_t *fragment, size_t fragment_size);
+
+int mfcc_set_config(struct processing_module *mod, uint32_t config_id,
+		    enum module_cfg_fragment_position pos, uint32_t data_offset_size,
+		    const uint8_t *fragment, size_t fragment_size, uint8_t *response,
+		    size_t response_size);
+
+#else
+static inline int mfcc_ipc_notification_init(struct processing_module *mod)
+{
+	return 0;
+}
+
+static inline void mfcc_send_vad_notification(struct processing_module *mod, uint32_t val)
+{
+}
+
+static inline int mfcc_get_config(struct processing_module *mod,
+				  uint32_t config_id, uint32_t *data_offset_size,
+				  uint8_t *fragment, size_t fragment_size)
+{
+	struct sof_ipc_ctrl_data *cdata = (struct sof_ipc_ctrl_data *)fragment;
+	struct mfcc_comp_data *cd = module_get_private_data(mod);
+
+	return comp_data_blob_get_cmd(cd->model_handler, cdata, fragment_size);
+}
+
+static inline int mfcc_set_config(struct processing_module *mod, uint32_t config_id,
+				  enum module_cfg_fragment_position pos, uint32_t data_offset_size,
+				  const uint8_t *fragment, size_t fragment_size, uint8_t *response,
+				  size_t response_size)
+{
+	struct mfcc_comp_data *cd = module_get_private_data(mod);
+
+	return comp_data_blob_set(cd->model_handler, pos, data_offset_size,
+				  fragment, fragment_size);
+}
+#endif
+
 #ifdef UNIT_TEST
 void sys_comp_module_mfcc_interface_init(void);
 #endif
diff --git a/tools/topology/topology2/platform/intel/sdw-dmic-audio-feature.conf b/tools/topology/topology2/platform/intel/sdw-dmic-audio-feature.conf
@@ -21,6 +21,21 @@ Object.Pipeline.host-gateway-src-mfcc-capture [
 					name "$SDW_DMIC_AUDIO_FEATURE_CAPTURE_PCM_NAME MFCC bytes"
 					<include/components/mfcc/mel80.conf>
 				}
+				mixer."1" {
+					name "$SDW_DMIC_AUDIO_FEATURE_CAPTURE_PCM_NAME MFCC VAD"
+					Object.Base.channel.1 {
+						name	"fc"
+						shift	0
+					}
+					Object.Base.ops.1 {
+						name	"ctl"
+						info	"volsw"
+						#259 binds the mixer control to switch get/put handlers
+						get	259
+						put	259
+					}
+					max 1
+				}
 			}
 		}
 	}
diff --git a/tools/topology/topology2/platform/intel/sdw-jack-audio-feature.conf b/tools/topology/topology2/platform/intel/sdw-jack-audio-feature.conf
@@ -21,6 +21,21 @@ Object.Pipeline.host-gateway-src-mfcc-capture [
 					name "$SDW_JACK_AUDIO_FEATURE_CAPTURE_PCM_NAME MFCC bytes"
 					<include/components/mfcc/mel80.conf>
 				}
+				mixer."1" {
+					name "$SDW_JACK_AUDIO_FEATURE_CAPTURE_PCM_NAME MFCC VAD"
+					Object.Base.channel.1 {
+						name	"fc"
+						shift	0
+					}
+					Object.Base.ops.1 {
+						name	"ctl"
+						info	"volsw"
+						#259 binds the mixer control to switch get/put handlers
+						get	259
+						put	259
+					}
+					max 1
+				}
 			}
 		}
 	}

Original file line number	Diff line number	Diff line change
`@@ -21,6 +21,21 @@ Object.Pipeline.host-gateway-src-mfcc-capture [`
`21`	`21`	`name "$SDW_DMIC_AUDIO_FEATURE_CAPTURE_PCM_NAME MFCC bytes"`
`22`	`22`	`<include/components/mfcc/mel80.conf>`
`23`	`23`	`}`
	`24`	`+ mixer."1" {`
	`25`	`+ name "$SDW_DMIC_AUDIO_FEATURE_CAPTURE_PCM_NAME MFCC VAD"`
	`26`	`+ Object.Base.channel.1 {`
	`27`	`+ name "fc"`
	`28`	`+ shift 0`
	`29`	`+ }`
	`30`	`+ Object.Base.ops.1 {`
	`31`	`+ name "ctl"`
	`32`	`+ info "volsw"`
	`33`	`+ #259 binds the mixer control to switch get/put handlers`
	`34`	`+ get 259`
	`35`	`+ put 259`
	`36`	`+ }`
	`37`	`+ max 1`
	`38`	`+ }`
`24`	`39`	`}`
`25`	`40`	`}`
`26`	`41`	`}`