Bluetooth: Controller: Fix ISO Tx PDU buffer counts for fragmentation

cvinayak · fabiobaltieri · commit 662acab1ae12 · 2025-02-24T20:18:37.000Z
Fix ISO Tx PDU buffer count required when SDU fragmentation
is used.

Rename BT_CTLR_CONN_ISO_SDU_LEN_MAX to
BT_CTLR_ISO_TX_SDU_LEN_MAX so the value is common to both
Broadcast and Connected ISO transmissions.

Signed-off-by: Vinayak Kariappa Chettimada &lt;vich@nordicsemi.no&gt;
diff --git a/samples/bluetooth/bap_broadcast_source/overlay-bt_ll_sw_split.conf b/samples/bluetooth/bap_broadcast_source/overlay-bt_ll_sw_split.conf
@@ -18,3 +18,4 @@ CONFIG_BT_CTLR_ISOAL_SOURCES=2
 # packet overhead (the Packet_Sequence_Number, ISO_SDU_Length, Packet_Status_Flag fields; and
 # the optional Time_Stamp field, if supplied)
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=163
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=155
diff --git a/samples/bluetooth/bap_unicast_client/overlay-bt_ll_sw_split.conf b/samples/bluetooth/bap_unicast_client/overlay-bt_ll_sw_split.conf
@@ -8,6 +8,7 @@ CONFIG_BT_CTLR_ISOAL_SINKS=1
 # packet overhead (the Packet_Sequence_Number, ISO_SDU_Length, Packet_Status_Flag fields; and
 # the optional Time_Stamp field, if supplied)
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=163
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=155
 
 CONFIG_BT_CTLR_ADVANCED_FEATURES=y
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
diff --git a/samples/bluetooth/bap_unicast_server/overlay-bt_ll_sw_split.conf b/samples/bluetooth/bap_unicast_server/overlay-bt_ll_sw_split.conf
@@ -8,6 +8,7 @@ CONFIG_BT_CTLR_ISOAL_SINKS=2
 # packet overhead (the Packet_Sequence_Number, ISO_SDU_Length, Packet_Status_Flag fields; and
 # the optional Time_Stamp field, if supplied)
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=163
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=155
 
 # Use the below if the sample is sending stale packet sequence number
 # CONFIG_BT_CTLR_ADVANCED_FEATURES=y
diff --git a/samples/bluetooth/cap_acceptor/overlay-bt_ll_sw_split.conf b/samples/bluetooth/cap_acceptor/overlay-bt_ll_sw_split.conf
@@ -9,3 +9,4 @@ CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=191
 # packet overhead (the Packet_Sequence_Number, ISO_SDU_Length, Packet_Status_Flag fields; and
 # the optional Time_Stamp field, if supplied)
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=163
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=155
diff --git a/samples/bluetooth/cap_initiator/overlay-bt_ll_sw_split.conf b/samples/bluetooth/cap_initiator/overlay-bt_ll_sw_split.conf
@@ -9,3 +9,4 @@ CONFIG_BT_CTLR_ADV_DATA_LEN_MAX=191
 # packet overhead (the Packet_Sequence_Number, ISO_SDU_Length, Packet_Status_Flag fields; and
 # the optional Time_Stamp field, if supplied)
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=163
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=155
diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_bis-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_bis-bt_ll_sw_split.conf
@@ -101,6 +101,7 @@ CONFIG_BT_CTLR_SYNC_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_ISOAL_SOURCES=4
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=12
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISO_RX_BUFFERS=8
diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_cis-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_cis-bt_ll_sw_split.conf
@@ -84,14 +84,14 @@ CONFIG_BT_CTLR_PERIPHERAL_ISO=y
 CONFIG_BT_CTLR_CONN_ISO_GROUPS=1
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=2
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=2
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISOAL_SOURCES=2
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=12
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISO_RX_BUFFERS=8
diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso-bt_ll_sw_split.conf
@@ -120,14 +120,14 @@ CONFIG_BT_CTLR_PERIPHERAL_ISO=y
 CONFIG_BT_CTLR_CONN_ISO_GROUPS=1
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=2
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=2
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISOAL_SOURCES=2
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=8
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISOAL_SINKS=2
diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_broadcast-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_broadcast-bt_ll_sw_split.conf
@@ -41,6 +41,7 @@ CONFIG_BT_CTLR_ISOAL_SOURCES=4
 
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=12
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 CONFIG_BT_CTLR_ADVANCED_FEATURES=y
 CONFIG_BT_CTLR_ADV_RESERVE_MAX=n
diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_central-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_central-bt_ll_sw_split.conf
@@ -49,14 +49,14 @@ CONFIG_BT_CTLR_PERIPHERAL_ISO=n
 CONFIG_BT_CTLR_CONN_ISO_GROUPS=1
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=2
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=2
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISOAL_SOURCES=2
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=12
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISOAL_SINKS=2
diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_peripheral-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_peripheral-bt_ll_sw_split.conf
@@ -49,14 +49,14 @@ CONFIG_BT_CTLR_PERIPHERAL_ISO=y
 CONFIG_BT_CTLR_CONN_ISO_GROUPS=1
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=2
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=2
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISOAL_SOURCES=2
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=12
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISOAL_SINKS=2
diff --git a/samples/bluetooth/hci_uart/overlay-all-bt_ll_sw_split.conf b/samples/bluetooth/hci_uart/overlay-all-bt_ll_sw_split.conf
@@ -115,14 +115,14 @@ CONFIG_BT_CTLR_PERIPHERAL_ISO=y
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=2
 CONFIG_BT_CTLR_CONN_ISO_GROUPS=1
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=2
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISOAL_SOURCES=4
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=18
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISOAL_SINKS=2
diff --git a/samples/bluetooth/hci_uart_3wire/overlay-all-bt_ll_sw_split.conf b/samples/bluetooth/hci_uart_3wire/overlay-all-bt_ll_sw_split.conf
@@ -114,14 +114,14 @@ CONFIG_BT_CTLR_PERIPHERAL_ISO=y
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=2
 CONFIG_BT_CTLR_CONN_ISO_GROUPS=1
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=2
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISOAL_SOURCES=4
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=18
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISOAL_SINKS=2
diff --git a/samples/bluetooth/iso_broadcast/overlay-bt_ll_sw_split.conf b/samples/bluetooth/iso_broadcast/overlay-bt_ll_sw_split.conf
@@ -14,7 +14,6 @@ CONFIG_BT_CTLR_ADV_ISO_PDU_LEN_MAX=4
 CONFIG_BT_CTLR_ADV_ISO_STREAM_MAX=2
 CONFIG_BT_CTLR_ISOAL_SOURCES=2
 
-# Support the highest SDU size required by any BAP LC3 presets (155) + 8 bytes of HCI ISO Data
-# packet overhead (the Packet_Sequence_Number, ISO_SDU_Length, Packet_Status_Flag fields; and
-# the optional Time_Stamp field, if supplied)
+# Support the highest SDU size required by this sample
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=12
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=4
diff --git a/samples/bluetooth/iso_central/overlay-bt_ll_sw_split.conf b/samples/bluetooth/iso_central/overlay-bt_ll_sw_split.conf
@@ -13,7 +13,7 @@ CONFIG_BT_CTLR_SCAN_DATA_LEN_MAX=1650
 CONFIG_BT_CTLR_RX_BUFFERS=9
 
 # Sufficient ISO SDU and PDU length for this sample with ISO_TX_MTU of 247
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 
 # Number of supported streami sources and sinks
diff --git a/samples/bluetooth/pbp_public_broadcast_source/overlay-bt_ll_sw_split.conf b/samples/bluetooth/pbp_public_broadcast_source/overlay-bt_ll_sw_split.conf
@@ -18,3 +18,4 @@ CONFIG_BT_CTLR_ISOAL_SOURCES=2
 # packet overhead (the Packet_Sequence_Number, ISO_SDU_Length, Packet_Status_Flag fields; and
 # the optional Time_Stamp field, if supplied)
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=163
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=155
diff --git a/subsys/bluetooth/controller/Kconfig b/subsys/bluetooth/controller/Kconfig
@@ -1071,13 +1071,13 @@ config BT_CTLR_CONN_ISO_PDU_LEN_MAX
 	help
 	  Maximum Connected Isochronous Channel PDU Length.
 
-config BT_CTLR_CONN_ISO_SDU_LEN_MAX
-	int "Maximum Connected Isochronous Channel SDU Length"
-	depends on BT_CTLR_CONN_ISO
+config BT_CTLR_ISO_TX_SDU_LEN_MAX
+	int "Maximum Isochronous Channel Transmit SDU Length"
+	depends on BT_CTLR_ADV_ISO || BT_CTLR_CONN_ISO
 	range 1 4095
-	default 251
+	default 1
 	help
-	  Maximum Connected Isochronous Channel SDU Length.
+	  Maximum Isochronous Channel Transmit SDU Length.
 
 config BT_CTLR_CONN_ISO_STREAMS_MAX_NSE
 	int "LE Connected Isochronous Streams max number of subevents"
diff --git a/subsys/bluetooth/controller/ll_sw/ull_iso_internal.h b/subsys/bluetooth/controller/ll_sw/ull_iso_internal.h
@@ -4,19 +4,44 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#if defined(CONFIG_BT_CTLR_ADV_ISO) || defined(CONFIG_BT_CTLR_CONN_ISO)
 /* Calculate ISO PDU buffers required considering SDU fragmentation */
-/* FIXME: Calculation considering both Connected and Broadcast ISO PDU
- *        fragmentation.
+#if defined(CONFIG_BT_CTLR_ADV_ISO) || defined(CONFIG_BT_CTLR_CONN_ISO)
+/* Internal ISO Tx SDU maximum length.
+ * A length that is minimum of the resultant combination of the HCI ISO data fragments provided and
+ * the user configured maximum transmit SDU length (CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX).
  */
-#if defined(CONFIG_BT_CTLR_CONN_ISO)
-#define BT_CTLR_ISO_TX_PDU_BUFFERS (((CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX + \
-				      CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX - 1U) / \
-				     CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX) * \
+#define BT_CTLR_ISO_TX_SDU_LEN_MAX MIN(((CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE * \
+					 CONFIG_BT_CTLR_ISO_TX_BUFFERS) - \
+					BT_HCI_ISO_SDU_HDR_SIZE), \
+				       CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX)
+
+BUILD_ASSERT(BT_CTLR_ISO_TX_SDU_LEN_MAX == CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX,
+	     "Insufficient ISO Buffer Size and Count for the required ISO SDU Length");
+
+/* Internal ISO Tx buffers to be allocated.
+ * Based on the internal ISO Tx SDU maximum length, calculate the required ISO Tx buffers (PDUs)
+ * required to fragment the SDU into PDU sizes scheduled for transmission.
+ */
+#if defined(CONFIG_BT_CTLR_ADV_ISO) && defined(CONFIG_BT_CTLR_CONN_ISO)
+#define BT_CTLR_ISO_TX_PDU_BUFFERS (DIV_ROUND_UP(BT_CTLR_ISO_TX_SDU_LEN_MAX, \
+						 MIN((CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE - \
+						      BT_HCI_ISO_SDU_TS_HDR_SIZE), \
+						     MIN(CONFIG_BT_CTLR_ADV_ISO_PDU_LEN_MAX, \
+							 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX))) * \
+				    CONFIG_BT_CTLR_ISO_TX_BUFFERS)
+#elif defined(CONFIG_BT_CTLR_ADV_ISO)
+#define BT_CTLR_ISO_TX_PDU_BUFFERS (DIV_ROUND_UP(BT_CTLR_ISO_TX_SDU_LEN_MAX, \
+						 MIN((CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE - \
+						      BT_HCI_ISO_SDU_TS_HDR_SIZE), \
+						     CONFIG_BT_CTLR_ADV_ISO_PDU_LEN_MAX)) * \
+				    CONFIG_BT_CTLR_ISO_TX_BUFFERS)
+#else /* CONFIG_BT_CTLR_CONN_ISO */
+#define BT_CTLR_ISO_TX_PDU_BUFFERS (DIV_ROUND_UP(BT_CTLR_ISO_TX_SDU_LEN_MAX, \
+						 MIN((CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE - \
+						      BT_HCI_ISO_SDU_TS_HDR_SIZE), \
+						     CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX)) * \
 				    CONFIG_BT_CTLR_ISO_TX_BUFFERS)
-#else /* !CONFIG_BT_CTLR_CONN_ISO */
-#define BT_CTLR_ISO_TX_PDU_BUFFERS CONFIG_BT_CTLR_ISO_TX_BUFFERS
-#endif /* !CONFIG_BT_CTLR_CONN_ISO */
+#endif /* CONFIG_BT_CTLR_CONN_ISO */
 #else /* !CONFIG_BT_CTLR_ADV_ISO && !CONFIG_BT_CTLR_CONN_ISO */
 #define BT_CTLR_ISO_TX_PDU_BUFFERS 0
 #endif /* !CONFIG_BT_CTLR_ADV_ISO && !CONFIG_BT_CTLR_CONN_ISO */
diff --git a/tests/bsim/bluetooth/audio/overlay-bt_ll_sw_split.conf b/tests/bsim/bluetooth/audio/overlay-bt_ll_sw_split.conf
@@ -71,14 +71,14 @@ CONFIG_BT_CTLR_PERIPHERAL_ISO=y
 CONFIG_BT_CTLR_CONN_ISO_GROUPS=1
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=2
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=2
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_LOW_LATENCY_POLICY=y
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISOAL_SOURCES=4
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=18
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=4095
 
 # ISO Receptions
 CONFIG_BT_CTLR_ISOAL_SINKS=4
diff --git a/tests/bsim/bluetooth/audio/overlay-nrf5340_cpunet_iso-bt_ll_sw_split.conf b/tests/bsim/bluetooth/audio/overlay-nrf5340_cpunet_iso-bt_ll_sw_split.conf
@@ -5,6 +5,7 @@
 CONFIG_BT_ISO_TX_BUF_COUNT=18
 
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=18
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=4095
 
 CONFIG_BT_CTLR_ADV_ISO_STREAM_COUNT=4
 CONFIG_BT_CTLR_ADV_ISO_STREAM_MAX=4
diff --git a/tests/bsim/bluetooth/host/iso/bis/prj.conf b/tests/bsim/bluetooth/host/iso/bis/prj.conf
@@ -23,6 +23,7 @@ CONFIG_BT_CTLR_ADV_ISO_STREAM_MAX=4
 CONFIG_BT_CTLR_SYNC_ISO=y
 CONFIG_BT_CTLR_SYNC_ISO_STREAM_MAX=4
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=208
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=200
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=4
 CONFIG_BT_CTLR_ISOAL_SOURCES=4
 CONFIG_BT_CTLR_ISOAL_SINKS=4
diff --git a/tests/bsim/bluetooth/host/iso/cis/prj.conf b/tests/bsim/bluetooth/host/iso/cis/prj.conf
@@ -21,6 +21,7 @@ CONFIG_BT_ISO_LOG_LEVEL_DBG=y
 CONFIG_BT_CTLR_CENTRAL_ISO=y
 CONFIG_BT_CTLR_PERIPHERAL_ISO=y
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=208
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=200
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=4
 CONFIG_BT_CTLR_ISOAL_SOURCES=2
 CONFIG_BT_CTLR_ISOAL_SINKS=2
diff --git a/tests/bsim/bluetooth/host/iso/frag/prj.conf b/tests/bsim/bluetooth/host/iso/frag/prj.conf
@@ -17,3 +17,4 @@ CONFIG_BT_ISO_LOG_LEVEL_DBG=y
 # Controller ISO configs
 CONFIG_BT_CTLR_ADV_ISO=y
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=20
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=12
diff --git a/tests/bsim/bluetooth/host/iso/frag_2/prj.conf b/tests/bsim/bluetooth/host/iso/frag_2/prj.conf
@@ -22,6 +22,7 @@ CONFIG_BT_ISO_RX_MTU=100
 # Controller ISO configs
 CONFIG_BT_CTLR_ADV_ISO=y
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=10
 
 # Controller Extended Advertising configs
diff --git a/tests/bsim/bluetooth/ll/bis/prj.conf b/tests/bsim/bluetooth/ll/bis/prj.conf
@@ -17,6 +17,7 @@ CONFIG_BT_CTLR_SYNC_ISO=y
 
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=2
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_ADV_ISO_PDU_LEN_MAX=247
 CONFIG_BT_CTLR_SYNC_ISO_PDU_LEN_MAX=251
 
diff --git a/tests/bsim/bluetooth/ll/bis/prj_vs_dp.conf b/tests/bsim/bluetooth/ll/bis/prj_vs_dp.conf
@@ -16,6 +16,7 @@ CONFIG_BT_CTLR_ADV_ISO=y
 CONFIG_BT_CTLR_SYNC_ISO=y
 
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_ADV_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_SYNC_ISO_PDU_LEN_MAX=251
 
diff --git a/tests/bsim/bluetooth/ll/cis/prj.conf b/tests/bsim/bluetooth/ll/cis/prj.conf
@@ -30,7 +30,6 @@ CONFIG_LOG=y
 CONFIG_BT_LL_SW_SPLIT=y
 CONFIG_BT_CTLR_CENTRAL_ISO=y
 CONFIG_BT_CTLR_PERIPHERAL_ISO=y
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=9
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=9
@@ -39,6 +38,7 @@ CONFIG_BT_CTLR_ISOAL_SINKS=9
 
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=18
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_ISO_RX_BUFFERS=1
 
 CONFIG_BT_CTLR_PHY_CODED=n
diff --git a/tests/bsim/bluetooth/ll/cis/sysbuild/hci_ipc/nrf5340_cpunet_iso_acl_group-bt_ll_sw_split.conf b/tests/bsim/bluetooth/ll/cis/sysbuild/hci_ipc/nrf5340_cpunet_iso_acl_group-bt_ll_sw_split.conf
@@ -94,14 +94,14 @@ CONFIG_BT_CTLR_SYNC_ISO_STREAM_MAX=2
 # ISO Connection Oriented
 CONFIG_BT_CTLR_CENTRAL_ISO=y
 CONFIG_BT_CTLR_PERIPHERAL_ISO=y
-CONFIG_BT_CTLR_CONN_ISO_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_CONN_ISO_PDU_LEN_MAX=251
 CONFIG_BT_CTLR_CONN_ISO_STREAMS=4
 CONFIG_BT_CTLR_CONN_ISO_STREAMS_PER_GROUP=4
 
 # ISO Transmissions
 CONFIG_BT_CTLR_ISO_TX_BUFFERS=18
 CONFIG_BT_CTLR_ISO_TX_BUFFER_SIZE=255
+CONFIG_BT_CTLR_ISO_TX_SDU_LEN_MAX=247
 CONFIG_BT_CTLR_ISOAL_SOURCES=4
 
 # ISO Receptions
