Bluetooth: Controller: Fix PDU length in case of ISR latency issue

In case of ISR latencies, if packet pointer has not been
set on time then we do not want to check uninitialized
length in rx buffer that did not get used by Radio DMA.
This would help us in detecting radio ready event being
set? We can not detect radio ready if it happens twice
before Radio ISR executes after latency.

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

Author: cvinayak

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

@@ -658,13 +658,23 @@ void lll_conn_isr_tx(void *param)
 
 void lll_conn_rx_pkt_set(struct lll_conn *lll)
 {
+	struct pdu_data *pdu_data_rx;
 	struct node_rx_pdu *node_rx;
 	uint16_t max_rx_octets;
 	uint8_t phy;
 
 	node_rx = ull_pdu_rx_alloc_peek(1);
 	LL_ASSERT(node_rx);
 
+	/* In case of ISR latencies, if packet pointer has not been set on time
+	 * then we do not want to check uninitialized length in rx buffer that
+	 * did not get used by Radio DMA. This would help us in detecting radio
+	 * ready event being set? We can not detect radio ready if it happens
+	 * twice before Radio ISR executes after latency.
+	 */
+	pdu_data_rx = (void *)node_rx->pdu;
+	pdu_data_rx->len = 0U;
+
 #if defined(CONFIG_BT_CTLR_DATA_LENGTH)
 #ifdef CONFIG_BT_LL_SW_LLCP_LEGACY
 	max_rx_octets = lll->max_rx_octets;
@@ -705,15 +715,15 @@ void lll_conn_rx_pkt_set(struct lll_conn *lll)
 #error "Undefined HAL_RADIO_PDU_LEN_MAX."
 #else
 		radio_pkt_rx_set(radio_ccm_rx_pkt_set(&lll->ccm_rx, phy,
-						      node_rx->pdu));
+						      pdu_data_rx));
 #endif
 #endif /* CONFIG_BT_CTLR_LE_ENC */
 	} else {
 		radio_pkt_configure(RADIO_PKT_CONF_LENGTH_8BIT, max_rx_octets,
 				    RADIO_PKT_CONF_FLAGS(RADIO_PKT_CONF_PDU_TYPE_DC, phy,
 							 RADIO_PKT_CONF_CTE_DISABLED));
 
-		radio_pkt_rx_set(node_rx->pdu);
+		radio_pkt_rx_set(pdu_data_rx);
 	}
 }