tests: bsim: Bluetooth: Deferred ACL Tx transmission setup

Added test to verify deferred ACL Tx transmission setup,
such that GATT discovery completes with least latency and
GATT notifications can be received earliest after connection
establishment.

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

tests/bsim/bluetooth/ll/compile.sh

@@ -17,6 +17,7 @@ app=tests/bsim/bluetooth/ll/advx \
   conf_overlay=overlay-ticker_expire_info.conf compile
 
 app=tests/bsim/bluetooth/ll/conn conf_file=prj_split.conf compile
+app=tests/bsim/bluetooth/ll/conn conf_file=prj_split_tx_defer.conf compile
 app=tests/bsim/bluetooth/ll/conn conf_file=prj_split_privacy.conf compile
 app=tests/bsim/bluetooth/ll/conn conf_file=prj_split_low_lat.conf compile
 app=tests/bsim/bluetooth/ll/conn conf_file=prj_split_single_timer.conf compile

tests/bsim/bluetooth/ll/conn/prj_split_tx_defer.conf

@@ -0,0 +1,19 @@
+CONFIG_BT=y
+CONFIG_LOG=y
+CONFIG_BT_CENTRAL=y
+CONFIG_BT_PERIPHERAL=y
+CONFIG_BT_PRIVACY=y
+CONFIG_BT_SMP=y
+CONFIG_BT_SIGNING=y
+CONFIG_BT_BAS=y
+CONFIG_BT_HRS=y
+CONFIG_BT_ATT_PREPARE_COUNT=2
+CONFIG_BT_GATT_CLIENT=y
+CONFIG_BT_L2CAP_DYNAMIC_CHANNEL=y
+CONFIG_BT_DEVICE_NAME="bsim_test_split"
+CONFIG_BT_L2CAP_TX_BUF_COUNT=6
+
+CONFIG_BT_CTLR_PRIVACY=n
+
+CONFIG_BT_CTLR_ADVANCED_FEATURES=y
+CONFIG_BT_CTLR_TX_DEFER=y

tests/bsim/bluetooth/ll/conn/src/test_connect1.c

@@ -60,6 +60,7 @@ static uint8_t connected_signal;
  */
 
 #define WAIT_TIME 6 /*seconds*/
+#define WAIT_TIME_TX_DEFER 800 /* milliseconds */
 #define WAIT_TIME_REPEAT 22 /*seconds*/
 extern enum bst_result_t bst_result;
 
@@ -77,7 +78,11 @@ extern enum bst_result_t bst_result;
 
 static void test_con1_init(void)
 {
-	bst_ticker_set_next_tick_absolute(WAIT_TIME*1e6);
+	if (IS_ENABLED(CONFIG_BT_CTLR_TX_DEFER)) {
+		bst_ticker_set_next_tick_absolute(WAIT_TIME_TX_DEFER*1e3);
+	} else {
+		bst_ticker_set_next_tick_absolute(WAIT_TIME*1e6);
+	}
 	bst_result = In_progress;
 }
 

tests/bsim/bluetooth/ll/conn/src/test_connect2.c

@@ -209,7 +209,11 @@ static void test_con2_main(void)
 	 * of starting delayed work so we do it here
 	 */
 	while (1) {
-		k_sleep(K_SECONDS(1));
+		if (IS_ENABLED(CONFIG_BT_CTLR_TX_DEFER)) {
+			k_sleep(K_MSEC(1));
+		} else {
+			k_sleep(K_SECONDS(1));
+		}
 
 		/* Heartrate measurements simulation */
 		hrs_notify();

tests/bsim/bluetooth/ll/conn/tests_scripts/basic_conn_split_tx_defer.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env bash
+# Copyright 2024 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+source ${ZEPHYR_BASE}/tests/bsim/sh_common.source
+
+# Basic connection test: a central connects to a peripheral and expects a
+# notification, using the split controller (ULL LLL)
+simulation_id="basic_conn_split_tx_defer"
+verbosity_level=2
+
+cd ${BSIM_OUT_PATH}/bin
+
+Execute ./bs_${BOARD_TS}_tests_bsim_bluetooth_ll_conn_prj_split_tx_defer_conf \
+  -v=${verbosity_level} -s=${simulation_id} -d=0 -RealEncryption=0 \
+  -testid=peripheral -rs=23
+
+Execute ./bs_${BOARD_TS}_tests_bsim_bluetooth_ll_conn_prj_split_tx_defer_conf\
+  -v=${verbosity_level} -s=${simulation_id} -d=1 -RealEncryption=0 \
+  -testid=central -rs=6
+
+Execute ./bs_2G4_phy_v1 -v=${verbosity_level} -s=${simulation_id} \
+  -D=2 -sim_length=20e6 $@
+
+wait_for_background_jobs