Bluetooth: Controller: Add LL_ASSERT_OVERHEAD define

Add LL_ASSERT_OVERHEAD define to reuse the assertion check
related to increase in actual EVENT_OVERHEAD_START_US value.

Introduce Kconfig option to permit radio event be skipped
when increased prepare callback latencies are measured,
instead of assertion.

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

Author: cvinayak

subsys/bluetooth/controller/Kconfig.ll_sw_split

@@ -458,6 +458,19 @@ config BT_CTLR_SCHED_ADVANCED
 	  Disabling this feature will lead to overlapping role in timespace
 	  leading to skipped events amongst active roles.
 
+config BT_CTLR_ASSERT_OVERHEAD_START
+	bool "Assert on Prepare Latency"
+	default y
+	help
+	  Assert on increased Radio Event Prepare callback latencies due to
+	  CPU usage overheads in the Controller implementation.
+
+	  Disabling this option permits the Controller to gracefully skip radio
+	  events that are delayed due to CPU usage latencies; as long as the
+	  radio event skips are not for every consecutive radio event interval,
+	  otherwise leading to remote supervision timeout and possible missing
+	  local disconnect events.
+
 config BT_CTLR_CENTRAL_SPACING
 	int "Central Connection Spacing"
 	depends on BT_CTLR_SCHED_ADVANCED

subsys/bluetooth/controller/hal/debug.h

@@ -27,4 +27,12 @@ void bt_ctlr_assert_handle(char *file, uint32_t line);
 		BT_ASSERT_MSG(cond, fmt, ##__VA_ARGS__)
 #endif
 
+#if defined(CONFIG_BT_CTLR_ASSERT_OVERHEAD_START)
+#define LL_ASSERT_OVERHEAD(overhead) \
+	LL_ASSERT_MSG(false, "%s: Actual EVENT_OVERHEAD_START_US = %u", \
+		      __func__, HAL_TICKER_TICKS_TO_US(overhead));
+#else /* !CONFIG_BT_CTLR_ASSERT_OVERHEAD_START */
+#define LL_ASSERT_OVERHEAD(overhead) ARG_UNUSED(overhead)
+#endif /* !CONFIG_BT_CTLR_ASSERT_OVERHEAD_START */
+
 #include "hal/debug_vendor_hal.h"

subsys/bluetooth/controller/ll_sw/lll_common.c

@@ -38,6 +38,8 @@ int lll_prepare(lll_is_abort_cb_t is_abort_cb, lll_abort_cb_t abort_cb,
 		lll_prepare_cb_t prepare_cb, int8_t event_prio,
 		struct lll_prepare_param *prepare_param)
 {
+	int err;
+
 #if defined(CONFIG_BT_CTLR_JIT_SCHEDULING)
 	int prio = event_prio;
 	struct lll_hdr *hdr = prepare_param->param;
@@ -60,20 +62,20 @@ int lll_prepare(lll_is_abort_cb_t is_abort_cb, lll_abort_cb_t abort_cb,
 	prepare_param->prio = prio;
 #endif /* CONFIG_BT_CTLR_JIT_SCHEDULING */
 
-	return lll_prepare_resolve(is_abort_cb, abort_cb, prepare_cb,
-				   prepare_param, 0, 0);
+	err = lll_prepare_resolve(is_abort_cb, abort_cb, prepare_cb, prepare_param, 0U, 0U);
+
+	return err;
 }
 
 void lll_resume(void *param)
 {
 	struct lll_event *next;
-	int ret;
+	int err;
 
 	next = param;
-	ret = lll_prepare_resolve(next->is_abort_cb, next->abort_cb,
-				  next->prepare_cb, &next->prepare_param,
-				  next->is_resume, 1);
-	LL_ASSERT(!ret || ret == -EINPROGRESS);
+	err = lll_prepare_resolve(next->is_abort_cb, next->abort_cb, next->prepare_cb,
+				  &next->prepare_param, next->is_resume, 1U);
+	LL_ASSERT(!err || err == -EINPROGRESS);
 }
 
 #if defined(CONFIG_BT_CTLR_JIT_SCHEDULING)

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

@@ -755,6 +755,11 @@ int lll_prepare_resolve(lll_is_abort_cb_t is_abort_cb, lll_abort_cb_t abort_cb,
 
 	err = prepare_cb(prepare_param);
 
+	if (!IS_ENABLED(CONFIG_BT_CTLR_ASSERT_OVERHEAD_START) &&
+	    (err == -ECANCELED)) {
+		err = 0;
+	}
+
 #if !defined(CONFIG_BT_CTLR_LOW_LAT)
 	uint32_t ret;
 

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

@@ -1041,8 +1041,8 @@ static int prepare_cb(struct lll_prepare_param *p)
 				    ticks_at_event);
 	/* check if preempt to start has changed */
 	if (overhead) {
-		LL_ASSERT_MSG(false, "%s: Actual EVENT_OVERHEAD_START_US = %u",
-			      __func__, HAL_TICKER_TICKS_TO_US(overhead));
+		LL_ASSERT_OVERHEAD(overhead);
+
 		radio_isr_set(isr_abort, lll);
 		radio_disable();
 

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

@@ -323,8 +323,8 @@ static int prepare_cb(struct lll_prepare_param *p)
 				    ticks_at_event);
 	/* check if preempt to start has changed */
 	if (overhead) {
-		LL_ASSERT_MSG(false, "%s: Actual EVENT_OVERHEAD_START_US = %u",
-			      __func__, HAL_TICKER_TICKS_TO_US(overhead));
+		LL_ASSERT_OVERHEAD(overhead);
+
 		radio_isr_set(lll_isr_abort, lll);
 		radio_disable();
 

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

@@ -425,8 +425,8 @@ static int prepare_cb_common(struct lll_prepare_param *p)
 	overhead = lll_preempt_calc(ull, (TICKER_ID_ADV_ISO_BASE + lll->handle), ticks_at_event);
 	/* check if preempt to start has changed */
 	if (overhead) {
-		LL_ASSERT_MSG(false, "%s: Actual EVENT_OVERHEAD_START_US = %u",
-			      __func__, HAL_TICKER_TICKS_TO_US(overhead));
+		LL_ASSERT_OVERHEAD(overhead);
+
 		radio_isr_set(lll_isr_abort, lll);
 		radio_disable();
 

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

@@ -244,8 +244,8 @@ static int prepare_cb(struct lll_prepare_param *p)
 					  ull_adv_sync_lll_handle_get(lll)), ticks_at_event);
 	/* check if preempt to start has changed */
 	if (overhead) {
-		LL_ASSERT_MSG(false, "%s: Actual EVENT_OVERHEAD_START_US = %u",
-			      __func__, HAL_TICKER_TICKS_TO_US(overhead));
+		LL_ASSERT_OVERHEAD(overhead);
+
 		radio_isr_set(lll_isr_abort, lll);
 		radio_disable();
 

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

@@ -246,8 +246,8 @@ static int prepare_cb(struct lll_prepare_param *p)
 	overhead = lll_preempt_calc(ull, (TICKER_ID_CONN_BASE + lll->handle), ticks_at_event);
 	/* check if preempt to start has changed */
 	if (overhead) {
-		LL_ASSERT_MSG(false, "%s: Actual EVENT_OVERHEAD_START_US = %u",
-			      __func__, HAL_TICKER_TICKS_TO_US(overhead));
+		LL_ASSERT_OVERHEAD(overhead);
+
 		radio_isr_set(lll_isr_abort, lll);
 		radio_disable();
 

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

@@ -384,8 +384,7 @@ static int prepare_cb(struct lll_prepare_param *p)
 				    ticks_at_event);
 	/* check if preempt to start has changed */
 	if (overhead) {
-		LL_ASSERT_MSG(false, "%s: Actual EVENT_OVERHEAD_START_US = %u",
-			      __func__, HAL_TICKER_TICKS_TO_US(overhead));
+		LL_ASSERT_OVERHEAD(overhead);
 
 		radio_isr_set(isr_done, cis_lll);
 		radio_disable();