From 1641eced0d0b19828899e0f75fc8ce7a25664cab Mon Sep 17 00:00:00 2001
From: Thomas <thomas.cuyckens@qorvo.com>
Date: Mon, 19 Dec 2022 23:50:54 +0100
Subject: [PATCH] [spinel] remove incorrect static_cast (#8512)

This should not be cast to an unsigned integer. If the
mRadioTimeOffset is negative, the resulting time instance is incorrect
and breaks e.g. CSL over RCP.
---
 src/lib/spinel/radio_spinel.hpp      | 2 +-
 src/lib/spinel/radio_spinel_impl.hpp | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/lib/spinel/radio_spinel.hpp b/src/lib/spinel/radio_spinel.hpp
index 4fd53b9f8..bc4d63397 100644
--- a/src/lib/spinel/radio_spinel.hpp
+++ b/src/lib/spinel/radio_spinel.hpp
@@ -1079,7 +1079,7 @@ private:
 
     uint64_t mTxRadioEndUs;
     uint64_t mRadioTimeRecalcStart; ///< When to recalculate RCP time offset.
-    int64_t  mRadioTimeOffset;      ///< Time difference with estimated RCP time minus host time.
+    uint64_t mRadioTimeOffset;      ///< Time difference with estimated RCP time minus host time.
 
     MaxPowerTable mMaxPowerTable;
 
diff --git a/src/lib/spinel/radio_spinel_impl.hpp b/src/lib/spinel/radio_spinel_impl.hpp
index 4c7b17e3c..0952453a4 100644
--- a/src/lib/spinel/radio_spinel_impl.hpp
+++ b/src/lib/spinel/radio_spinel_impl.hpp
@@ -218,7 +218,7 @@ RadioSpinel<InterfaceType, ProcessContextType>::RadioSpinel(void)
 #endif
     , mTxRadioEndUs(UINT64_MAX)
     , mRadioTimeRecalcStart(UINT64_MAX)
-    , mRadioTimeOffset(0)
+    , mRadioTimeOffset(UINT64_MAX)
 {
     mVersion[0] = '\0';
     memset(&mRadioSpinelMetrics, 0, sizeof(mRadioSpinelMetrics));
@@ -2201,7 +2201,7 @@ void RadioSpinel<InterfaceType, ProcessContextType>::CalcRcpTimeOffset(void)
 
     VerifyOrExit(error == OT_ERROR_NONE, mRadioTimeRecalcStart = localRxTimestamp);
 
-    mRadioTimeOffset      = static_cast<int64_t>(remoteTimestamp - ((localRxTimestamp / 2) + (localTxTimestamp / 2)));
+    mRadioTimeOffset      = (remoteTimestamp - ((localRxTimestamp / 2) + (localTxTimestamp / 2)));
     mIsTimeSynced         = true;
     mRadioTimeRecalcStart = localRxTimestamp + RCP_TIME_OFFSET_CHECK_INTERVAL;
 
@@ -2213,7 +2213,7 @@ exit:
 template <typename InterfaceType, typename ProcessContextType>
 uint64_t RadioSpinel<InterfaceType, ProcessContextType>::GetNow(void)
 {
-    return mIsTimeSynced ? (otPlatTimeGet() + static_cast<uint64_t>(mRadioTimeOffset)) : UINT64_MAX;
+    return (mIsTimeSynced) ? (otPlatTimeGet() + mRadioTimeOffset) : UINT64_MAX;
 }
 
 template <typename InterfaceType, typename ProcessContextType>