Bluetooth: Controller: Fix nRF51x advertising channel PDU regression

Fix nRF51x series advertising channel PDU S1 byte
configuration regression, that causes corrupted advertising
PDUs being reported to Host, by adding the missing bits_s1
local variable initialization.

Regression introduced in commit 1dcbe73 ("Bluetooth:
controller: radio: add setting of S1 byte in radio packet").

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

Author: cvinayak

subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/radio/radio.c

@@ -348,9 +348,10 @@ void radio_pkt_configure(uint8_t bits_len, uint8_t max_len, uint8_t flags)
 	/* nRF51 supports only 27 byte PDU when using h/w CCM for encryption. */
 	if (!IS_ENABLED(CONFIG_BT_CTLR_DATA_LENGTH_CLEAR) &&
 	    pdu_type == RADIO_PKT_CONF_PDU_TYPE_DC) {
-		bits_len = 5U;
-		bits_s1 = 3U;
+		bits_len = RADIO_PKT_CONF_LENGTH_5BIT;
 	}
+	bits_s1 = RADIO_PKT_CONF_LENGTH_8BIT - bits_len;
+
 #elif defined(CONFIG_SOC_COMPATIBLE_NRF52X) || \
 	defined(CONFIG_SOC_SERIES_NRF53X)
 	extra = 0U;
@@ -389,7 +390,7 @@ void radio_pkt_configure(uint8_t bits_len, uint8_t max_len, uint8_t flags)
 			  RADIO_PCNF0_S1INCL_Pos) & RADIO_PCNF0_S1INCL_Msk;
 #if defined(CONFIG_BT_CTLR_DF)
 		if (RADIO_PKT_CONF_CTE_GET(flags) == RADIO_PKT_CONF_CTE_ENABLED) {
-			bits_s1 = 8U;
+			bits_s1 = RADIO_PKT_CONF_S1_8BIT;
 		} else
 #endif /* CONFIG_BT_CTLR_DF */
 		{

subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/radio/radio.h

@@ -26,6 +26,10 @@
 
 /* Macro to define length of the BLE packet length field in bits */
 #define RADIO_PKT_CONF_LENGTH_8BIT (8U)
+#define RADIO_PKT_CONF_LENGTH_5BIT (5U)
+
+/* Macro to define length of the BLE packet S1 field in bits */
+#define RADIO_PKT_CONF_S1_8BIT (8U)
 
 /* Helper macro to create bitfield with PDU type only*/
 #define RADIO_PKT_CONF_PDU_TYPE(phy) ((uint8_t)((phy) << RADIO_PKT_CONF_PDU_TYPE_POS))