Bluetooth: Controller: Disable connection event continuation on overlap

Disable connection event continuation on overlap with same
connection's next event. This implementation has bugs and
needs to be fixed in subsequent commits.

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

Author: cvinayak

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

@@ -69,6 +69,7 @@ static uint8_t crc_valid;
 static uint8_t is_aborted;
 static uint16_t tx_cnt;
 static uint16_t trx_cnt;
+static uint8_t trx_busy_iteration;
 
 #if defined(CONFIG_BT_CTLR_LE_ENC)
 static uint8_t mic_state;
@@ -153,13 +154,21 @@ void lll_conn_prepare_reset(void)
 	crc_valid = 0U;
 	crc_expire = 0U;
 	is_aborted = 0U;
+	trx_busy_iteration = 0U;
 
 #if defined(CONFIG_BT_CTLR_LE_ENC)
 	mic_state = LLL_CONN_MIC_NONE;
 #endif /* CONFIG_BT_CTLR_LE_ENC */
 }
 
 #if defined(CONFIG_BT_CENTRAL)
+/* Number of times central event being aborted by same event instance be skipped */
+/* FIXME: Increasing this causes event pipeline overflow assertion, add LLL implementation to
+ *        gracefully abort the deferred next event when -EBUSY is returned in this is_abort_cb
+ *        interface.
+ */
+#define CENTRAL_TRX_BUSY_ITERATION_MAX 0
+
 int lll_conn_central_is_abort_cb(void *next, void *curr,
 				 lll_prepare_cb_t *resume_cb)
 {
@@ -171,7 +180,9 @@ int lll_conn_central_is_abort_cb(void *next, void *curr,
 			return 0;
 		}
 
-	} else if (trx_cnt < 1U) {
+	} else if ((trx_cnt < 1U) && (trx_busy_iteration < CENTRAL_TRX_BUSY_ITERATION_MAX)) {
+		trx_busy_iteration++;
+
 		/* Do not be aborted by same event if a single central's Rx has not completed.
 		 * Cases where single trx duration can be greater than connection interval.
 		 */
@@ -183,6 +194,13 @@ int lll_conn_central_is_abort_cb(void *next, void *curr,
 #endif /* CONFIG_BT_CENTRAL */
 
 #if defined(CONFIG_BT_PERIPHERAL)
+/* Number of times peripheral event being aborted by same event instance be skipped */
+/* FIXME: Increasing this causes event pipeline overflow assertion, add LLL implementation to
+ *        gracefully abort the deferred next event when -EBUSY is returned in this is_abort_cb
+ *        interface.
+ */
+#define PERIPHERAL_TRX_BUSY_ITERATION_MAX 0
+
 int lll_conn_peripheral_is_abort_cb(void *next, void *curr,
 				    lll_prepare_cb_t *resume_cb)
 {
@@ -194,7 +212,9 @@ int lll_conn_peripheral_is_abort_cb(void *next, void *curr,
 			return 0;
 		}
 
-	} else if (tx_cnt < 1U) {
+	} else if ((tx_cnt < 1U) && (trx_busy_iteration < PERIPHERAL_TRX_BUSY_ITERATION_MAX)) {
+		trx_busy_iteration++;
+
 		/* Do not be aborted by same event if a single peripheral's Tx has not completed.
 		 * Cases where single trx duration can be greater than connection interval.
 		 */