Bluetooth: controller: Move RSSI sampling after pkt processing

Move the code to acquire the RSSI sample after critical
control path that processes PDUs.

This is needed to reduce the time taken to assign the next
packet ptr inside radio ISR.

Signed-off-by: Vinayak Kariappa Chettimada <[email protected]>

Author: cvinayak

subsys/bluetooth/controller/ll_sw/ctrl.c

@@ -3239,29 +3239,6 @@ static inline void isr_rx_conn(u8_t crc_ok, u8_t trx_done,
 	u8_t chg = 0;
 #endif /* CONFIG_BT_CTLR_PROFILE_ISR */
 
-#if defined(CONFIG_BT_CTLR_CONN_RSSI)
-	/* Collect RSSI for connection */
-	if (_radio.packet_counter == 0) {
-		if (rssi_ready) {
-			u8_t rssi = radio_rssi_get();
-
-			_radio.conn_curr->rssi_latest = rssi;
-
-			if (((_radio.conn_curr->rssi_reported - rssi) & 0xFF) >
-			    RADIO_RSSI_THRESHOLD) {
-				if (_radio.conn_curr->rssi_sample_count) {
-					_radio.conn_curr->rssi_sample_count--;
-				}
-			} else {
-				_radio.conn_curr->rssi_sample_count =
-					RADIO_RSSI_SAMPLE_COUNT;
-			}
-		}
-	}
-#else /* !CONFIG_BT_CTLR_CONN_RSSI */
-	ARG_UNUSED(rssi_ready);
-#endif /* !CONFIG_BT_CTLR_CONN_RSSI */
-
 	/* Increment packet counter for this connection event */
 	_radio.packet_counter++;
 
@@ -3386,6 +3363,13 @@ static inline void isr_rx_conn(u8_t crc_ok, u8_t trx_done,
 
 #endif /* CONFIG_BT_CTLR_PROFILE_ISR */
 
+	/* NOTE: Check for connection termination and skip accessing connection
+	 * context.
+	 */
+	if (!_radio.conn_curr) {
+		goto isr_rx_conn_terminate_exit;
+	}
+
 	/* release tx node and generate event for num complete */
 	if (tx_release) {
 		pdu_node_tx_release(_radio.conn_curr->handle, tx_release);
@@ -3401,6 +3385,29 @@ static inline void isr_rx_conn(u8_t crc_ok, u8_t trx_done,
 		packet_rx_enqueue();
 	}
 
+#if defined(CONFIG_BT_CTLR_CONN_RSSI)
+	/* Collect RSSI for connection */
+	if (rssi_ready) {
+		u8_t rssi = radio_rssi_get();
+
+		_radio.conn_curr->rssi_latest = rssi;
+
+		if (((_radio.conn_curr->rssi_reported - rssi) & 0xFF) >
+		    RADIO_RSSI_THRESHOLD) {
+			if (_radio.conn_curr->rssi_sample_count) {
+				_radio.conn_curr->rssi_sample_count--;
+			}
+		} else {
+			_radio.conn_curr->rssi_sample_count =
+				RADIO_RSSI_SAMPLE_COUNT;
+		}
+	}
+#else /* !CONFIG_BT_CTLR_CONN_RSSI */
+	ARG_UNUSED(rssi_ready);
+#endif /* !CONFIG_BT_CTLR_CONN_RSSI */
+
+isr_rx_conn_terminate_exit:
+
 #if defined(CONFIG_BT_CTLR_PROFILE_ISR)
 	/* calculate the elapsed time in us since on-air radio packet end
 	 * to ISR entry