Bluetooth: Controller: Fix HCI command buffer allocation failure

Fix HCI command buffer allocation failure, that can cause
loss of Host Number of Completed Packets command.

Fail by rejecting the HCI Host Buffer Size command if the
required number of HCI command buffers are not allocated in
the Controller implementation.

When Controller to Host data flow control is supported in
the Controller only build, ensure that BT_BUF_CMD_TX_COUNT
is greater than or equal to (BT_BUF_RX_COUNT + Ncmd),
where Ncmd is supported maximum Num_HCI_Command_Packets in
the Controller implementation.

Relates to commit 8161430 ("Bluetooth: Add workaround
for no command buffer available")'.

Relates to commit 297f4f4 ("Bluetooth: Split HCI
command & event buffers to two pools").

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>

Author: cvinayak

include/zephyr/bluetooth/buf.h

@@ -97,13 +97,13 @@ 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 (CONFIG_BT_MAX_CONN + 1)
+  *       remove the MAX and only keep the 1.
   */
-#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)
+#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)
 #else
-#define BT_BUF_ACL_RX_COUNT 0
+#define BT_BUF_ACL_RX_COUNT_EXTRA 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
@@ -117,10 +117,15 @@ 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))
 
-/** 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))
+/* 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))
 
 /** Data size needed for HCI Command buffers. */
 #define BT_BUF_CMD_TX_SIZE BT_BUF_CMD_SIZE(CONFIG_BT_BUF_CMD_TX_SIZE)

samples/bluetooth/central_hr/prj_minimal.conf

@@ -94,7 +94,7 @@ 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=2
+CONFIG_BT_BUF_EVT_RX_COUNT=4
 
 CONFIG_BT_L2CAP_TX_BUF_COUNT=2
 CONFIG_BT_CTLR_RX_BUFFERS=1

samples/bluetooth/hci_ipc/nrf5340_cpunet_bis-bt_ll_sw_split.conf

@@ -10,12 +10,7 @@ CONFIG_HEAP_MEM_POOL_SIZE=4096
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 
-# 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

samples/bluetooth/hci_ipc/nrf5340_cpunet_bt_mesh-bt_ll_sw_split.conf

@@ -10,11 +10,6 @@ CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 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
 

samples/bluetooth/hci_ipc/nrf5340_cpunet_cis-bt_ll_sw_split.conf

@@ -10,12 +10,7 @@ CONFIG_HEAP_MEM_POOL_SIZE=4096
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 
-# 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

samples/bluetooth/hci_ipc/nrf5340_cpunet_df-bt_ll_sw_split.conf

@@ -10,12 +10,7 @@ CONFIG_HEAP_MEM_POOL_SIZE=4096
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 
-# 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

samples/bluetooth/hci_ipc/nrf5340_cpunet_iso-bt_ll_sw_split.conf

@@ -14,12 +14,7 @@ CONFIG_LTO=y
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 
-# 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

samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_broadcast-bt_ll_sw_split.conf

@@ -10,10 +10,6 @@ CONFIG_HEAP_MEM_POOL_SIZE=4096
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 
-# 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
-
 # Host and Controller common dependencies
 CONFIG_BT_BROADCASTER=y
 CONFIG_BT_OBSERVER=n

samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_central-bt_ll_sw_split.conf

@@ -10,10 +10,6 @@ CONFIG_HEAP_MEM_POOL_SIZE=4096
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 
-# 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

samples/bluetooth/hci_ipc/nrf5340_cpunet_iso_peripheral-bt_ll_sw_split.conf

@@ -10,10 +10,6 @@ CONFIG_HEAP_MEM_POOL_SIZE=4096
 CONFIG_BT=y
 CONFIG_BT_HCI_RAW=y
 
-# 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