nrfconnect · cvinayak · Nov 12, 2025 · Nov 12, 2025 · Nov 12, 2025 · Nov 7, 2024
diff --git a/include/zephyr/bluetooth/buf.h b/include/zephyr/bluetooth/buf.h
@@ -100,13 +100,13 @@ struct bt_buf_data {
   * available for the HCI driver to allocate from.
   *
   * TODO: When CONFIG_BT_BUF_ACL_RX_COUNT is removed,
-  *       remove the MAX and only keep the 1.
+  *       remove the MAX and only keep (CONFIG_BT_MAX_CONN + 1)
   */
-#define BT_BUF_ACL_RX_COUNT_EXTRA CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA
-#define BT_BUF_ACL_RX_COUNT       (MAX(CONFIG_BT_BUF_ACL_RX_COUNT, 1) + BT_BUF_ACL_RX_COUNT_EXTRA)
+#define BT_BUF_ACL_RX_COUNT                                                                        \
+	(MAX(CONFIG_BT_BUF_ACL_RX_COUNT, (CONFIG_BT_MAX_CONN + 1)) +                               \
+	 CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA)
 #else
-#define BT_BUF_ACL_RX_COUNT_EXTRA 0
-#define BT_BUF_ACL_RX_COUNT       0
+#define BT_BUF_ACL_RX_COUNT 0
 #endif /* CONFIG_BT_CONN && CONFIG_BT_HCI_HOST */
 
 #if defined(CONFIG_BT_BUF_ACL_RX_COUNT) && CONFIG_BT_BUF_ACL_RX_COUNT > 0
@@ -120,15 +120,10 @@ BUILD_ASSERT(BT_BUF_ACL_RX_COUNT <= BT_BUF_ACL_RX_COUNT_MAX,
 #define BT_BUF_RX_SIZE (MAX(MAX(BT_BUF_ACL_RX_SIZE, BT_BUF_EVT_RX_SIZE), \
 			    BT_BUF_ISO_RX_SIZE))
 
-/* Controller can generate up to CONFIG_BT_BUF_ACL_TX_COUNT number of unique HCI Number of Completed
- * Packets events.
- */
-BUILD_ASSERT(CONFIG_BT_BUF_EVT_RX_COUNT > CONFIG_BT_BUF_ACL_TX_COUNT,
-	     "Increase Event RX buffer count to be greater than ACL TX buffer count");
-
-/** Buffer count needed for HCI ACL or HCI ISO plus Event RX buffers */
-#define BT_BUF_RX_COUNT (CONFIG_BT_BUF_EVT_RX_COUNT + \
-			 MAX(BT_BUF_ACL_RX_COUNT, BT_BUF_ISO_RX_COUNT))
+/** Buffer count needed for HCI ACL, HCI ISO or Event RX buffers */
+#define BT_BUF_RX_COUNT (MAX(MAX(CONFIG_BT_BUF_EVT_RX_COUNT, \
+				 BT_BUF_ACL_RX_COUNT), \
+			     BT_BUF_ISO_RX_COUNT))
 
 /** Data size needed for HCI Command buffers. */
 #define BT_BUF_CMD_TX_SIZE BT_BUF_CMD_SIZE(CONFIG_BT_BUF_CMD_TX_SIZE)

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
@@ -13,7 +13,12 @@ CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 CONFIG_BT_MAX_CONN=2
 
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 CONFIG_BT_BUF_EVT_RX_COUNT=16
+
 CONFIG_BT_BUF_EVT_RX_SIZE=255
 CONFIG_BT_BUF_ACL_RX_SIZE=255
 CONFIG_BT_BUF_ACL_TX_SIZE=251

diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_bt_mesh-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_bt_mesh-bt_ll_sw_split.conf
@@ -11,6 +11,11 @@ CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 CONFIG_BT_MAX_CONN=16
 
+
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 # Controller
 CONFIG_BT_LL_SW_SPLIT=y
 

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
@@ -13,7 +13,12 @@ CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 CONFIG_BT_MAX_CONN=2
 
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 CONFIG_BT_BUF_EVT_RX_COUNT=16
+
 CONFIG_BT_BUF_EVT_RX_SIZE=255
 CONFIG_BT_BUF_ACL_RX_SIZE=255
 CONFIG_BT_BUF_ACL_TX_SIZE=251

diff --git a/samples/bluetooth/hci_ipc/nrf5340_cpunet_df-bt_ll_sw_split.conf b/samples/bluetooth/hci_ipc/nrf5340_cpunet_df-bt_ll_sw_split.conf
@@ -13,7 +13,12 @@ CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 CONFIG_BT_MAX_CONN=2
 
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 CONFIG_BT_BUF_EVT_RX_COUNT=16
+
 CONFIG_BT_BUF_EVT_RX_SIZE=255
 CONFIG_BT_BUF_ACL_RX_SIZE=255
 CONFIG_BT_BUF_ACL_TX_SIZE=251

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
@@ -13,7 +13,12 @@ CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 CONFIG_BT_MAX_CONN=2
 
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 CONFIG_BT_BUF_EVT_RX_COUNT=16
+
 CONFIG_BT_BUF_EVT_RX_SIZE=255
 CONFIG_BT_BUF_ACL_RX_SIZE=255
 CONFIG_BT_BUF_ACL_TX_SIZE=251

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
@@ -12,6 +12,10 @@ CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 CONFIG_BT_BUF_EVT_RX_SIZE=255
 CONFIG_BT_BUF_ACL_RX_SIZE=255
 CONFIG_BT_BUF_ACL_TX_SIZE=251

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
@@ -12,6 +12,10 @@ CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 CONFIG_BT_BUF_EVT_RX_SIZE=255
 CONFIG_BT_BUF_ACL_RX_SIZE=255
 CONFIG_BT_BUF_ACL_TX_SIZE=251

diff --git a/samples/bluetooth/hci_ipc/prj.conf b/samples/bluetooth/hci_ipc/prj.conf
@@ -11,6 +11,11 @@ CONFIG_BT_HCI_RAW=y
 CONFIG_BT_HCI_RAW_RESERVE=1
 CONFIG_BT_MAX_CONN=16
 
+
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
+
 # Enable and adjust the below value as necessary
 # CONFIG_BT_BUF_EVT_RX_COUNT=16
 # CONFIG_BT_BUF_EVT_RX_SIZE=255

diff --git a/samples/bluetooth/hci_uart/prj.conf b/samples/bluetooth/hci_uart/prj.conf
@@ -17,3 +17,7 @@ CONFIG_BT_TINYCRYPT_ECC=n
 CONFIG_BT_CTLR_DTM_HCI=y
 
 CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=512
+
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
diff --git a/samples/bluetooth/hci_usb/prj.conf b/samples/bluetooth/hci_usb/prj.conf
@@ -11,3 +11,7 @@ CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=n
 CONFIG_SERIAL=n
 CONFIG_CONSOLE=n
 CONFIG_UART_CONSOLE=n
+
+# Workaround: Unable to allocate command buffer when using K_NO_WAIT since
+# Host number of completed commands does not follow normal flow control.
+CONFIG_BT_BUF_CMD_TX_COUNT=10
diff --git a/samples/bluetooth/mesh/boards/bbc_microbit.conf b/samples/bluetooth/mesh/boards/bbc_microbit.conf
@@ -13,11 +13,9 @@ CONFIG_BT_PERIPHERAL=n
 CONFIG_BT_EXT_ADV=n
 CONFIG_BT_RX_STACK_SIZE=1100
 CONFIG_BT_BUF_EVT_RX_COUNT=3
+CONFIG_BT_BUF_ACL_RX_COUNT_EXTRA=1
 CONFIG_BT_BUF_EVT_DISCARDABLE_COUNT=3
 
-# CONFIG_BT_BUF_ACL_TX_COUNT has to be less than CONFIG_BT_BUF_EVT_RX_COUNT
-CONFIG_BT_BUF_ACL_TX_COUNT=1
-
 CONFIG_BT_CTLR_ADV_EXT=n
 
 CONFIG_BT_MESH_ADV_BUF_COUNT=3

diff --git a/samples/bluetooth/peripheral_hr/prj_minimal.conf b/samples/bluetooth/peripheral_hr/prj_minimal.conf
@@ -101,7 +101,7 @@ CONFIG_BT_CTLR_PHY_2M=n
 # Reduce Bluetooth buffers
 CONFIG_BT_BUF_EVT_DISCARDABLE_COUNT=1
 CONFIG_BT_BUF_EVT_DISCARDABLE_SIZE=45
-CONFIG_BT_BUF_EVT_RX_COUNT=4
+CONFIG_BT_BUF_EVT_RX_COUNT=2
 
 CONFIG_BT_CONN_TX_MAX=2
 CONFIG_BT_L2CAP_TX_BUF_COUNT=2

diff --git a/subsys/bluetooth/common/Kconfig b/subsys/bluetooth/common/Kconfig
@@ -93,23 +93,15 @@ config BT_BUF_ACL_RX_SIZE
 	  K-frame.
 
 config BT_BUF_ACL_RX_COUNT_EXTRA
-	# As Host implementation unconditionally references this Kconfig, we
-	# hide it for !BT_CONN and default to 0.
-	int "Number of extra incoming ACL data buffers" if BT_CONN
-	range 1 65535 if BT_CONN
-	default BT_MAX_CONN if BT_CONN
-	range 0 0
+	int "Number of extra incoming ACL data buffers"
 	default 0
+	range 0 65535
 	help
 	  Number of incoming extra ACL data buffers sent from the Controller to
 	  the Host.
 
-	  By default, the total number of incoming ACL data buffers is equal to
-	  CONFIG_BT_MAX_CONN + 1, to support L2CAP recombination.
-
-	  The L2CAP recombination in the Host keeps the first Rx buffer for each
-	  connection and uses one Rx buffer across all connections to receive a
-	  fragment from the Controller.
+	  By default, the number of incoming ACL data buffers is equal to
+	  CONFIG_BT_MAX_CONN + 1.
 
 config BT_BUF_ACL_RX_COUNT
 	int "[DEPRECATED] Number of incoming ACL data buffers"
@@ -143,8 +135,7 @@ config BT_BUF_EVT_RX_SIZE
 
 config BT_BUF_EVT_RX_COUNT
 	int "Number of HCI Event buffers"
-	default 8 if BT_HCI_RAW
-	default 4 if BT_RECV_BLOCKING
+	default 3 if BT_RECV_BLOCKING
 	default 20 if (BT_MESH && !(BT_BUF_EVT_DISCARDABLE_COUNT > 0))
 	default 10
 	range 2 255
@@ -201,48 +192,12 @@ config BT_BUF_CMD_TX_SIZE
 	  to the maximum of 255.
 
 config BT_BUF_CMD_TX_COUNT
-	# This option is only visible for a user when Host and Controller are build together, or for
-	# Host-only builds.
-	int "Number of HCI command buffers" if !BT_HCI_RAW || !BT_CTLR
-	# This option is present when Host and Controller are build together, or
-	# for Host only builds, or when Controller-to-Host ACL data flow control
-	# is disabled.
-	depends on !BT_HCI_RAW || !BT_CTLR || !BT_HCI_ACL_FLOW_CONTROL
-	# The Mesh stack usage in applications and tests can start both advertising and scanning in
-	# parallel. Also, when BT_MESH_WORKQ_SYS is enabled, the Mesh stack is starting Extended
-	# Advertising in the receive callback run in the system work queue and as the Host also uses
-	# the system work queue for HCI command Tx towards the Controller, one additional HCI
-	# command buffer is needed.
-	range 2 64 if BT_MESH
-	range 1 64
-	default 2 if BT_MESH
-	default 1
+	int "Number of HCI command buffers"
+	default 2
+	range 2 64
 	help
 	  Number of buffers available for outgoing HCI commands from the Host.
 
-	  HCI Controllers may not support Num_HCI_Command_Packets > 1, hence they default to 1 when
-	  not enabling Controller to Host data flow control (BT_HCI_ACL_FLOW_CONTROL), Read Remote
-	  Version Information (BT_REMOTE_VERSION), Auto-Initiate PHY update (BT_AUTO_PHY_UPDATE), or
-	  Auto-Initiate Data Length Update (BT_AUTO_DATA_LEN_UPDATE).
-
-	  Normal HCI commands follow the HCI command flow control using Num_HCI_Command_Packets
-	  return in HCI command complete and status.
-
-	  The Host Number of Completed Packets command does not follow normal flow control of HCI
-	  commands and the Controller side HCI drivers that allocates HCI command buffers with
-	  K_NO_WAIT can end up running out of command buffers.
-
-	  When Controller to Host data flow control is enabled in the Host-only or combined
-	  Host plus Controller build, the internal BT_BUF_CMD_TX_COUNT is adjusted accordingly
-	  taking into considerations the enabled auto-initiated procedures, and to follow the normal
-	  HCI command flow control to be able to send Ncmd normal HCI commands and
-	  BT_BUF_ACL_RX_COUNT of Host Number of Completed Packets command down to the Controller.
-
-	  When Controller to Host data flow control is supported in the Controller-only build,
-	  the internal BT_BUF_CMD_TX_COUNT is adjusted to be equal to (BT_BUF_RX_COUNT + Ncmd).
-
-	  Where Ncmd is supported maximum Num_HCI_Command_Packets in the Controller implementation.
-
 endmenu
 
 config BT_HAS_HCI_VS

diff --git a/subsys/bluetooth/common/hci_common_internal.h b/subsys/bluetooth/common/hci_common_internal.h
diff --git a/subsys/bluetooth/controller/Kconfig b/subsys/bluetooth/controller/Kconfig
@@ -127,15 +127,6 @@ endchoice
 
 comment "BLE Controller configuration"
 
-config BT_CTLR_HCI_NUM_CMD_PKT_MAX
-	# Hidden Controller implementation supported Num_HCI_Command_Packets value.
-	# This value will be used to calculate the total number of HCI command buffers to be
-	# allocated, BT_BUF_CMD_TX_COUNT, dependent on HCI Controller to Host data flow control
-	# being enabled.
-	int
-	default 1 if BT_LL_SW_SPLIT
-	default 1
-
 config BT_CTLR_CRYPTO
 	bool "Crypto functions in Controller"
 	default y