[radio] fix low power multi-vendor certification failures

OpenThread stack update change 992be2781->a363396eb (in commit 2c459e3a3) had a change in the stack to clarify and adjust various CSL timing units to existing 802.15.4 standards based timing concepts.

See openthread/openthread@6da6e09

One of the changes was to clarify that the rxTimestamp (used to calculate "next" CSL transmissions) should point to the end of the sync header (SHR). So when scheduling our transmit, we must make sure to subtract the SHR duration value from our base time since this is already accounted for when calculating next CSL transmission delay.

Co-authored-by: Suvesh Pratapa <[email protected]>

src/src/radio.c

@@ -407,6 +407,8 @@ static const RAIL_IEEE802154_Config_t sRailIeee802154Config = {
 #define SHR_SIZE 5 // 4 bytes of preamble, 1 byte sync-word
 #endif
 
+#define SHR_DURATION_US 160 // Duration of SHR in us.
+
 // Misc
 static volatile uint32_t miscRadioState = 0;
 static bool              emPendingData  = false;
@@ -1634,7 +1636,8 @@ otError otPlatRadioTransmit(otInstance *aInstance, otRadioFrame *aFrame)
             sTxFrame->mInfo.mTxInfo.mTxDelay         = 3000; // Chosen after internal certification testing
         }
 #endif
-        updateIeInfoTxFrame(sTxFrame->mInfo.mTxInfo.mTxDelayBaseTime + sTxFrame->mInfo.mTxInfo.mTxDelay + 160);
+        updateIeInfoTxFrame(sTxFrame->mInfo.mTxInfo.mTxDelayBaseTime + sTxFrame->mInfo.mTxInfo.mTxDelay +
+                            SHR_DURATION_US);
         // Note - we need to call this outside of txCurrentPacket as for Series 2,
         // this results in calling the SE interface from a critical section which is not permitted.
 
@@ -1823,8 +1826,8 @@ void txCurrentPacket(void)
         // Note that both use single CCA config, overriding any CCA/CSMA configs from the stack
         //
 #if OPENTHREAD_CONFIG_THREAD_VERSION >= OT_THREAD_VERSION_1_2
-        RAIL_ScheduleTxConfig_t scheduleTxOptions = {.when = sTxFrame->mInfo.mTxInfo.mTxDelayBaseTime
-                                                             + sTxFrame->mInfo.mTxInfo.mTxDelay,
+        RAIL_ScheduleTxConfig_t scheduleTxOptions = {.when = sTxFrame->mInfo.mTxInfo.mTxDelayBaseTime +
+                                                             sTxFrame->mInfo.mTxInfo.mTxDelay - SHR_DURATION_US,
                                                      .mode       = RAIL_TIME_ABSOLUTE,
                                                      .txDuringRx = RAIL_SCHEDULED_TX_DURING_RX_POSTPONE_TX};
 
@@ -3032,8 +3035,9 @@ static bool validatePacketTimestamp(RAIL_RxPacketDetails_t *pPacketDetails, uint
     // Get the timestamp when the SFD was received
     otEXPECT_ACTION(pPacketDetails->timeReceived.timePosition != RAIL_PACKET_TIME_INVALID, rxTimestampValid = false);
 
-    // + 1 for the 1-byte PHY header
-    pPacketDetails->timeReceived.totalPacketBytes = packetLength + 1;
+    // + PHY HEADER SIZE for PHY header
+    // We would not need this if PHR is not included and we want the MHR
+    pPacketDetails->timeReceived.totalPacketBytes = packetLength + PHY_HEADER_SIZE;
 
     otEXPECT_ACTION((RAIL_GetRxTimeSyncWordEndAlt(gRailHandle, pPacketDetails) == RAIL_STATUS_NO_ERROR),
                     rxTimestampValid = false);