Bluetooth: Controller: Fix timings for Tx test

The Tx interval is now calculated at the beginning
of the Tx test and the next transmission is
triggerd by the switch timer instead of event
timer. This fixes a corner case issue when
timer rollover.

Signed-off-by: Kamil Gawor <Kamil.Gawor@nordicsemi.no>

subsys/bluetooth/controller/ll_sw/nordic/lll/lll_test.c

@@ -71,7 +71,8 @@ static uint8_t        test_chan;
 static uint8_t        test_slot_duration;
 #endif /* CONFIG_BT_CTLR_DTM_HCI_DF_IQ_REPORT */
 
-static uint16_t       test_num_rx;
+static uint32_t    tx_tifs;
+static uint16_t    test_num_rx;
 static bool        started;
 
 /* NOTE: The PRBS9 sequence used as packet payload.
@@ -170,8 +171,6 @@ static int create_iq_report(bool crc_ok)
 
 static void isr_tx(void *param)
 {
-	uint32_t l, i, s, t;
-
 	/* Clear radio status and events */
 	radio_status_reset();
 	radio_tmr_status_reset();
@@ -187,38 +186,17 @@ static void isr_tx(void *param)
 		return;
 	}
 
-	/* LE Test Packet Interval */
-	l = radio_tmr_end_get() - radio_tmr_ready_get();
-
-#if defined(CONFIG_BT_CTLR_DF_CTE_TX)
-	i = ceiling_fraction((l + CTE_LEN_US(test_cte_len) + 249), SCAN_INT_UNIT_US) *
-	    SCAN_INT_UNIT_US;
-#else
-	i = ceiling_fraction((l + 249), SCAN_INT_UNIT_US) * SCAN_INT_UNIT_US;
-#endif /* CONFIG_BT_CTLR_DF_CTE_TX */
-
-	t = radio_tmr_end_get() - l + i;
-	t -= radio_tx_ready_delay_get(test_phy, test_phy_flags);
-
-	/* Set timer capture in the future. */
-	radio_tmr_sample();
-	s = radio_tmr_sample_get();
-	while (t < s) {
-		t += SCAN_INT_UNIT_US;
-	}
-
 	/* Setup next Tx */
-	radio_switch_complete_and_disable();
-	radio_tmr_start_us(1, t);
-	radio_tmr_aa_capture();
-	radio_tmr_end_capture();
+	radio_tmr_tifs_set(tx_tifs);
+	radio_switch_complete_and_b2b_tx(test_phy, test_phy_flags, test_phy, test_phy_flags);
 
-	/* TODO: check for probable stale timer capture being set */
+	radio_tmr_end_capture();
 
 #if defined(HAL_RADIO_GPIO_HAVE_PA_PIN)
 	radio_gpio_pa_setup();
-	radio_gpio_pa_lna_enable(t + radio_tx_ready_delay_get(test_phy,
-							      test_phy_flags) -
+	radio_gpio_pa_lna_enable(radio_tmr_tifs_base_get() +
+				 tx_tifs -
+				 radio_tx_ready_delay_get(test_phy, test_phy_flags) -
 				 HAL_RADIO_GPIO_PA_OFFSET);
 #endif /* HAL_RADIO_GPIO_HAVE_PA_PIN */
 }
@@ -482,6 +460,28 @@ static bool check_rx_cte(bool cte_ready)
 }
 #endif /* CONFIG_BT_CTLR_DF_CTE_RX */
 
+static uint32_t calculate_tifs(uint8_t len)
+{
+	uint32_t interval;
+	uint32_t transmit_time;
+
+#if defined(CONFIG_BT_CTLR_DF_CTE_TX)
+	/* Include additional byte for the CTEInfo field and CTE length in microseconds. */
+	transmit_time = PDU_US((test_cte_len > 0) ? (len + 1) : len, 0, test_phy, test_phy_flags) +
+			CTE_LEN_US(test_cte_len);
+#else
+	transmit_time = PDU_US(len, 0, test_phy, test_phy_flags);
+#endif /* CONFIG_BT_CTLR_DF_CTE_TX */
+
+	/* Ble Core Specification Vol 6 Part F 4.1.6
+	 * LE Test packet interval: I(L) = ceil((L + 249) / 625) * 625 us
+	 * where L is an LE Test packet length in microseconds unit.
+	 */
+	interval = ceiling_fraction((transmit_time + 249), SCAN_INT_UNIT_US) * SCAN_INT_UNIT_US;
+
+	return interval - transmit_time;
+}
+
 static uint8_t init(uint8_t chan, uint8_t phy, int8_t tx_power,
 		    bool cte, void (*isr)(void *))
 {
@@ -520,7 +520,6 @@ static uint8_t init(uint8_t chan, uint8_t phy, int8_t tx_power,
 	/* Setup Radio in Tx/Rx */
 	/* NOTE: No whitening in test mode. */
 	radio_phy_set(test_phy, test_phy_flags);
-	radio_tmr_tifs_set(EVENT_IFS_US);
 
 	ret = tx_power_set(tx_power);
 
@@ -634,9 +633,12 @@ uint8_t ll_test_tx(uint8_t chan, uint8_t len, uint8_t type, uint8_t phy,
 	test_cte_len = cte_len;
 #endif /* CONFIG_BT_CTLR_DF_CTE_TX */
 
-	radio_switch_complete_and_disable();
+	tx_tifs = calculate_tifs(len);
+
+	radio_tmr_tifs_set(tx_tifs);
+	radio_switch_complete_and_b2b_tx(test_phy, test_phy_flags, test_phy, test_phy_flags);
+
 	start_us = radio_tmr_start(1, cntr_cnt_get() + CNTR_MIN_DELTA, 0);
-	radio_tmr_aa_capture();
 	radio_tmr_end_capture();
 
 #if defined(HAL_RADIO_GPIO_HAVE_PA_PIN)
@@ -698,6 +700,7 @@ uint8_t ll_test_rx(uint8_t chan, uint8_t phy, uint8_t mod_idx, uint8_t expected_
 #endif /* CONFIG_BT_CTLR_DTM_HCI_DF_IQ_REPORT */
 
 	radio_pkt_rx_set(radio_pkt_scratch_get());
+	radio_tmr_tifs_set(EVENT_IFS_US);
 	radio_switch_complete_and_b2b_rx(test_phy, test_phy_flags, test_phy, test_phy_flags);
 	radio_tmr_start(0, cntr_cnt_get() + CNTR_MIN_DELTA, 0);