topology: kpb: add topology-configurable history buffer depth

Add a bytes kcontrol kpb_cfg_<N> to each KPB widget that lets the
topology manifest set the ring-buffer pre-roll duration at load time,
without a firmware rebuild.

Firmware (IPC4 path):
- ipc4/kpb.h: add KP_BUF_CFG_BUFF_TIME_MS = 2 to the param-ID enum
- kpb.c: add buff_time_ms field to comp_data; add kpb_get_buff_time_ms()
  helper (returns topology value when set, falls back to
  CONFIG_KPB_MAX_BUFF_TIME); wire the helper into kpb_params(),
  kpb_prepare() buffer allocation, drain-request cap; handle the new
  LARGE_CONFIG_SET case in kpb_set_large_config()

Topology:
- kpb.conf: add Object.Control.bytes kpb_cfg_$index with IncludeByKey
  blobs for 6000/4000/2100 ms; blob is a 36-byte sof_abi_hdr + u32 ms
- dmic-wov-multi-manifest.conf: Define KPB_BUFF_TIME_MS 6000 for TGL

The kernel sof_ipc4_widget_kcontrol_setup() path sends the blob as a
LARGE_CONFIG_SET on pipeline open with no userspace intervention.
Omitting KPB_BUFF_TIME_MS from the manifest leaves buff_time_ms = 0,
and kpb_get_buff_time_ms() falls back to CONFIG_KPB_MAX_BUFF_TIME.

Verified on spider (TGL/CAVS2.5): kpb_cfg_101/102/103 kcontrols appear
after modprobe; topology file size increased from 22001 to 22829 bytes.

Author: lrgirdwo

src/audio/kpb.c

@@ -104,6 +104,7 @@ struct comp_data {
 	enum comp_copy_type force_copy_type; /**< should we force copy_type on kpb sink? */
 #ifdef CONFIG_IPC_MAJOR_4
 	struct ipc4_kpb_module_cfg ipc4_cfg;
+	uint32_t buff_time_ms; /**< history depth in ms; 0 = CONFIG_KPB_MAX_BUFF_TIME */
 #endif /* CONFIG_IPC_MAJOR_4 */
 	uint32_t num_of_sel_mic;
 	uint32_t num_of_in_channels;
@@ -236,6 +237,17 @@ static void kpb_lock_init(struct comp_data *kpb)
 
 #endif /* __ZEPHYR__ */
 
+
+/* Return per-instance history depth (ms); fall back to Kconfig if not set via topology. */
+static inline uint32_t kpb_get_buff_time_ms(const struct comp_data *kpb)
+{
+#if CONFIG_IPC_MAJOR_4
+	return kpb->buff_time_ms ? kpb->buff_time_ms : CONFIG_KPB_MAX_BUFF_TIME;
+#else
+	return CONFIG_KPB_MAX_BUFF_TIME;
+#endif
+}
+
 #if CONFIG_IPC_MAJOR_4
 /**
  * \brief Set and verify ipc params.
@@ -298,7 +310,7 @@ static void kpb_set_params(struct comp_dev *dev,
 	params->sample_valid_bytes =
 		kpb->ipc4_cfg.base_cfg.audio_fmt.valid_bit_depth / 8;
 	params->buffer_fmt = kpb->ipc4_cfg.base_cfg.audio_fmt.interleaving_style;
-	params->buffer.size = kpb->ipc4_cfg.base_cfg.ibs * KPB_MAX_BUFF_TIME * params->channels;
+	params->buffer.size = kpb->ipc4_cfg.base_cfg.ibs * kpb_get_buff_time_ms(kpb) * params->channels;
 
 	params->host_period_bytes = params->channels *
 				    params->sample_container_bytes *
@@ -809,7 +821,11 @@ static int kpb_prepare(struct comp_dev *dev)
 	struct sof_ipc_stream_params params;
 	int ret = 0;
 	int i;
-	size_t hb_size_req = KPB_MAX_BUFFER_SIZE(kpb->config.sampling_width, kpb->config.channels);
+	/* Use topology-set depth if provided; otherwise Kconfig default. */
+	uint32_t buff_ms = kpb_get_buff_time_ms(kpb);
+	size_t hb_size_req = (KPB_SAMPLNG_FREQUENCY / 1000) *
+		(KPB_SAMPLE_CONTAINER_SIZE(kpb->config.sampling_width) / 8) *
+		buff_ms * kpb->config.channels;
 
 	comp_dbg(dev, "entry");
 
@@ -1768,7 +1784,7 @@ static void kpb_init_draining(struct comp_dev *dev, struct kpb_client *cli)
 	/* TODO: check also if client is registered */
 	} else if (!is_sink_ready) {
 		comp_err(dev, "sink not ready for draining");
-	} else if (cli->drain_req > KPB_MAX_DRAINING_REQ) {
+	} else if (cli->drain_req > kpb_get_buff_time_ms(kpb)) {
 		comp_cl_err(&comp_kpb, "drain request exceeds max");
 	} else {
 		if (kpb->hd.buffered < drain_req) {
@@ -2854,6 +2870,16 @@ static int kpb_set_large_config(struct comp_dev *dev, uint32_t param_id,
 #endif
 	case KP_BUF_CLIENT_MIC_SELECT:
 		return kpb_set_micselect(dev, data, data_offset);
+#if CONFIG_IPC_MAJOR_4
+	case KP_BUF_CFG_BUFF_TIME_MS: {
+		struct comp_data *kpb = comp_get_drvdata(dev);
+		if (data_offset < sizeof(uint32_t))
+			return -EINVAL;
+		kpb->buff_time_ms = *(const uint32_t *)data;
+		comp_info(dev, "kpb: buff_time_ms set to %u ms", kpb->buff_time_ms);
+		return 0;
+	}
+#endif
 	default:
 		return -EINVAL;
 	}

src/audio/wov_arbiter/README.md

@@ -882,10 +882,10 @@ Key parameters in `dmic-wov-multi.conf`:
 | `VAD_GATE_CPC` | `5000` | cycles per chunk for VAD gate |
 | `FORMAT` | `s16le` | audio format throughout |
 
-> **KPB history depth is not a topology parameter.** It is controlled exclusively by the
-> `CONFIG_KPB_MAX_BUFF_TIME` Kconfig option (see [Build System Configuration](#build-system-configuration)).
-> The topology `kpb.conf` class exposes no history-depth attribute; the buffer is
-> allocated at `prepare()` time using the compiled-in value.
+> **KPB history depth is configurable via topology.** Set `KPB_BUFF_TIME_MS` in the topology
+> manifest (e.g. `dmic-wov-multi-manifest.conf`) to override `CONFIG_KPB_MAX_BUFF_TIME` at
+> runtime — no firmware rebuild required.  Omit the define or set it to `0` to fall back to
+> the Kconfig default (6000 ms on TGL/CAVS2.5, 2100 ms on other platforms).
 
 Slot 2 (`Pipeline 103`) is deliberately placed on Core 1 (`core_id = 1`) to validate
 cross-core scheduling. Set all three to `core_id = 0` if a single-core topology is needed.
@@ -923,22 +923,35 @@ CONFIG_SMP=y
 CONFIG_MP_MAX_NUM_CPUS=4       # TGL has 4 DSP cores
 CONFIG_SCHED_CPU_MASK_PIN_ONLY=y
 
-# KPB history buffer length (compile-time only — not exposed in topology)
-# Default: 6000 ms on CAVS2.5+ (TigerLake), 2100 ms on all other platforms
+# KPB history buffer length — compile-time floor; topology can override at runtime.
+# Default: 6000 ms on CAVS2.5+ (TigerLake), 2100 ms on all other platforms.
 # Override example: west build -- -DCONFIG_KPB_MAX_BUFF_TIME=4000
 CONFIG_KPB_MAX_BUFF_TIME=6000  # TGL / CAVS2.5
 ```
 
-The KPB history depth is **not** configurable via topology.  The buffer size is computed
-at prepare time as:
+The KPB history depth can be set **per-platform in the topology manifest** without a
+firmware rebuild.  The buffer size is computed at prepare time from whichever source wins:
+
+| Source | Priority | How to set |
+|---|---|---|
+| Topology `KPB_BUFF_TIME_MS` | **highest** | `Define { KPB_BUFF_TIME_MS "6000" }` in manifest |
+| `CONFIG_KPB_MAX_BUFF_TIME` | fallback | `west build -- -DCONFIG_KPB_MAX_BUFF_TIME=4000` |
+
+Buffer byte formula (16 kHz S16LE mono):
 
 ```
-buffer_bytes = (16000 / 1000) × (sample_width_bytes) × CONFIG_KPB_MAX_BUFF_TIME × channels
-             = 16 × 2 × 6000 × 1  =  192 000 bytes   (TGL, S16LE mono)
-             = 16 × 2 × 2100 × 1  =   67 200 bytes   (other platforms)
+buffer_bytes = 16 x 2 x buff_time_ms x channels
+             = 16 x 2 x 6000 x 1  =  192 000 bytes   (TGL, S16LE mono, 6000 ms)
+             = 16 x 2 x 2100 x 1  =   67 200 bytes   (other platforms, 2100 ms)
 ```
 
-To change the pre-roll window, rebuild with `-DCONFIG_KPB_MAX_BUFF_TIME=<ms>`.
+The topology kcontrol `kpb_cfg_<N>` carries a 36-byte SOF ABI blob with
+`type = KP_BUF_CFG_BUFF_TIME_MS = 2` and a 4-byte `uint32_t` payload.  It is sent
+automatically to the firmware LARGE_CONFIG_SET handler when the pipeline is first opened;
+no userspace script is required.  Supported values in `kpb.conf`: `6000`, `4000`, `2100`.
+To add a new value, compute the 4-byte LE payload and add an `IncludeByKey` entry.
+
+To change the compile-time fallback, rebuild with `-DCONFIG_KPB_MAX_BUFF_TIME=<ms>`.
 
 The `CONFIG_VAD_GATE_DEFAULT_THRESHOLD` (if exposed) compiles in a non-zero threshold; otherwise
 the compiled-in default is 0 (pass-through).  Always set the threshold at runtime via

src/include/ipc4/kpb.h

@@ -24,6 +24,8 @@ struct ipc4_kpb_module_cfg {
 enum ipc4_kpb_module_config_params {
 	/*! Configure the module ID's which would be part of the Fast mode tasks */
 	KP_BUF_CFG_FM_MODULE = 1,
+	/*! Set history ring-buffer duration; 0 = use CONFIG_KPB_MAX_BUFF_TIME */
+	KP_BUF_CFG_BUFF_TIME_MS = 2,
 	/* Mic selector for client - sets microphone id for real time sink mic selector
 	 * IPC4-compatible ID - please do not change the number
 	 */

tools/topology/topology2/dmic-wov-multi-manifest.conf

@@ -104,6 +104,12 @@ Define {
 	VAD_GATE_CPC   5000
 }
 
+# KPB history ring-buffer depth: 6000 ms for TGL/CAVS2.5 (6 s pre-roll).
+# Omit or set to 0 to fall back to CONFIG_KPB_MAX_BUFF_TIME.
+Define {
+	KPB_BUFF_TIME_MS	"6000"
+}
+
 # ---------------------------------------------------------------------------
 # Pipeline 100 — DAI (Core 0)
 # DMIC DAI copier → VAD Gate → Mixin (fan-out to 3 Mixouts in 101/102/103)

tools/topology/topology2/include/components/kpb.conf

@@ -59,6 +59,43 @@ Class.Widget."kpb" {
 		unique	"instance"
 	}
 
+	Object.Control.bytes."1" {
+		name "kpb_cfg_$index"
+		access [
+			tlv_read
+			tlv_write
+			tlv_callback
+		]
+		Object.Base.extops."extctl" {
+			get 258
+			put 258
+		}
+		max 64
+		Object.Base.data."1" {
+			IncludeByKey.KPB_BUFF_TIME_MS {
+				# sof_abi_hdr{magic, type=KP_BUF_CFG_BUFF_TIME_MS=2, size=4, abi=4.0} + u32 ms
+				# 6000 ms = 0x00001770
+				'6000' {bytes "0x53, 0x4f, 0x46, 0x34, 0x02, 0x00, 0x00, 0x00,
+						0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04,
+						0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+						0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+						0x70, 0x17, 0x00, 0x00"}
+				# 4000 ms = 0x00000FA0
+				'4000' {bytes "0x53, 0x4f, 0x46, 0x34, 0x02, 0x00, 0x00, 0x00,
+						0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04,
+						0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+						0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+						0xa0, 0x0f, 0x00, 0x00"}
+				# 2100 ms = 0x00000834
+				'2100' {bytes "0x53, 0x4f, 0x46, 0x34, 0x02, 0x00, 0x00, 0x00,
+						0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04,
+						0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+						0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+						0x34, 0x08, 0x00, 0x00"}
+			}
+		}
+	}
+
 	#
 	# Default attributes for kpb
 	#