Bluetooth: Add delay before sending Connection Update

BLUETOOTH SPECIFICATION Version 4.2 [Vol 3, Part C] page 368:

  "The Peripheral device should not perform a Connection Parameter Update
   procedure within T GAP (conn_pause_peripheral) after establishing a
   connection."

> HCI Event: LE Meta Event (0x3e) plen 19 [hci1] 11:14:22.496358
      LE Connection Complete (0x01)
        Status: Success (0x00)
        Handle: 74
        Role: Slave (0x01)
        Peer address type: Public (0x00)
        Peer address: 7C:7A:91:18:82:46 (Intel Corporate)
        Connection interval: 70.00 msec (0x0038)
        Connection latency: 0.00 msec (0x0000)
        Supervision timeout: 420 msec (0x002a)
        Master clock accuracy: 0x01
...[5 seconds interval]...
< ACL Data TX: Handle 74 flags 0x00 dlen 16 [hci1] 11:14:27.493541
      LE L2CAP: Connection Parameter Update Request (0x12) ident 1 len 8
        Min interval: 24
        Max interval: 40
        Slave latency: 0
        Timeout multiplier: 42

Change-Id: Ibb301ea00c127542ba299ad0b94825ad1ed05c5c
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/conn.c

@@ -136,6 +136,21 @@ void notify_le_param_updated(struct bt_conn *conn)
 	}
 }
 
+static void le_conn_update(struct nano_work *work)
+{
+	struct bt_conn_le *le = CONTAINER_OF(work, struct bt_conn_le,
+					     update_work);
+	struct bt_conn *conn = CONTAINER_OF(le, struct bt_conn, le);
+	const struct bt_le_conn_param *param;
+
+	param = BT_LE_CONN_PARAM(conn->le.interval_min,
+				 conn->le.interval_max,
+				 conn->le.latency,
+				 conn->le.timeout);
+
+	bt_conn_le_param_update(conn, param);
+}
+
 static struct bt_conn *conn_new(void)
 {
 	struct bt_conn *conn = NULL;
@@ -1005,6 +1020,7 @@ struct bt_conn *bt_conn_add_le(const bt_addr_le_t *peer)
 	conn->type = BT_CONN_TYPE_LE;
 	conn->le.interval_min = BT_GAP_INIT_CONN_INT_MIN;
 	conn->le.interval_max = BT_GAP_INIT_CONN_INT_MAX;
+	nano_delayed_work_init(&conn->le.update_work, le_conn_update);
 
 	return conn;
 }
@@ -1086,6 +1102,10 @@ void bt_conn_set_state(struct bt_conn *conn, bt_conn_state_t state)
 			notify_connected(conn);
 		}
 
+		/* Cancel Connection Update if it is pending */
+		if (conn->type == BT_CONN_TYPE_LE)
+			nano_delayed_work_cancel(&conn->le.update_work);
+
 		/* Release the reference we took for the very first
 		 * state transition.
 		 */
@@ -1289,6 +1309,9 @@ int bt_conn_le_param_update(struct bt_conn *conn,
 		return -EALREADY;
 	}
 
+	/* Cancel any pending update */
+	nano_delayed_work_cancel(&conn->le.update_work);
+
 	if ((conn->role == BT_HCI_ROLE_SLAVE) &&
 	    !(bt_dev.le.features[0] & BT_HCI_LE_CONN_PARAM_REQ_PROC)) {
 		return bt_l2cap_update_conn_param(conn, param);

net/bluetooth/conn_internal.h

@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (c) 2015-2016 Intel Corporation
+ * Copyright (c) 2015 Intel Corporation
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+#include <misc/nano_work.h>
 
 typedef enum __packed {
 	BT_CONN_DISCONNECTED,
@@ -50,6 +51,9 @@ struct bt_conn_le {
 	uint16_t		timeout;
 
 	uint8_t			features[8];
+
+	/* Delayed work for connection update handling */
+	struct nano_delayed_work update_work;
 };
 
 #if defined(CONFIG_BLUETOOTH_BREDR)
@@ -135,7 +139,7 @@ void bt_conn_ssp_auth(struct bt_conn *conn, uint32_t passkey);
 /* Look up an existing connection */
 struct bt_conn *bt_conn_lookup_handle(uint16_t handle);
 
-/* Look up a connection state. For NULL peer, returns the first connection
+/* Look up a connection state. For BT_ADDR_LE_ANY, returns the first connection
  * with the specific state
  */
 struct bt_conn *bt_conn_lookup_state_le(const bt_addr_le_t *peer,

net/bluetooth/hci_core.c

@@ -58,6 +58,9 @@
 #define BT_DBG(fmt, ...)
 #endif
 
+/* Peripheral timeout to initialize Connection Parameter Update procedure */
+#define CONN_UPDATE_TIMEOUT	(5 * sys_clock_ticks_per_sec)
+
 /* Stacks for the fibers */
 static BT_STACK_NOINIT(rx_fiber_stack, CONFIG_BLUETOOTH_RX_STACK_SIZE);
 static BT_STACK_NOINIT(cmd_tx_fiber_stack, 256);
@@ -590,15 +593,16 @@ static int hci_le_read_remote_features(struct bt_conn *conn)
 	return 0;
 }
 
-static int update_conn_param(struct bt_conn *conn)
+static void update_conn_param(struct bt_conn *conn)
 {
-	const struct bt_le_conn_param *param;
+	/*
-
+	 * Core 4.2 Vol 3, Part C, 9.3.12.2
-	param = BT_LE_CONN_PARAM(conn->le.interval_min,
+	 * The Peripheral device should not perform a Connection Parameter
-				 conn->le.interval_max,
+	 * Update procedure within 5 s after establishing a connection.
-				 conn->le.latency,
+	 */
-				 conn->le.timeout);
+	nano_delayed_work_submit(&conn->le.update_work,
-	return bt_conn_le_param_update(conn, param);
+				 conn->role == BT_HCI_ROLE_MASTER ? TICKS_NONE :
+				 CONN_UPDATE_TIMEOUT);
 }
 
 static void le_conn_complete(struct net_buf *buf)