From a68cd059cc7293b6a2ed449bfc9cd944a4ca3ed3 Mon Sep 17 00:00:00 2001
From: Eduardo Montoya <edmont@users.noreply.github.com>
Date: Mon, 18 Jul 2022 23:12:20 +0200
Subject: [PATCH] [csl] update CSL information in radio when parent changes
 (#7911)

Cover the case of parent change while the CSL child is still attached.
---
 src/core/mac/sub_mac.cpp | 9 ++++++---
 src/core/mac/sub_mac.hpp | 1 +
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/core/mac/sub_mac.cpp b/src/core/mac/sub_mac.cpp
index 01243de7a..7d5cccdc9 100644
--- a/src/core/mac/sub_mac.cpp
+++ b/src/core/mac/sub_mac.cpp
@@ -97,6 +97,7 @@ void SubMac::Init(void)
 #if OPENTHREAD_CONFIG_MAC_CSL_RECEIVER_ENABLE
     mCslPeriod     = 0;
     mCslChannel    = 0;
+    mCslPeerShort  = 0;
     mIsCslSampling = false;
     mCslSampleTime = TimeMicro{0};
     mCslLastSync   = TimeMicro{0};
@@ -1051,13 +1052,15 @@ bool SubMac::UpdateCsl(uint16_t aPeriod, uint8_t aChannel, otShortAddress aShort
 {
     bool diffPeriod  = aPeriod != mCslPeriod;
     bool diffChannel = aChannel != mCslChannel;
-    bool retval      = diffPeriod || diffChannel;
+    bool diffPeer    = aShortAddr != mCslPeerShort;
+    bool retval      = diffPeriod || diffChannel || diffPeer;
 
     VerifyOrExit(retval);
     mCslChannel = aChannel;
 
-    VerifyOrExit(diffPeriod);
-    mCslPeriod = aPeriod;
+    VerifyOrExit(diffPeriod || diffPeer);
+    mCslPeriod    = aPeriod;
+    mCslPeerShort = aShortAddr;
     IgnoreError(Get<Radio>().EnableCsl(aPeriod, aShortAddr, aExtAddr));
 
     mCslTimer.Stop();
diff --git a/src/core/mac/sub_mac.hpp b/src/core/mac/sub_mac.hpp
index 0904351e3..8eccfe9f5 100644
--- a/src/core/mac/sub_mac.hpp
+++ b/src/core/mac/sub_mac.hpp
@@ -662,6 +662,7 @@ private:
     uint8_t  mCslChannel : 7; // The CSL sample channel.
     bool mIsCslSampling : 1;  // Indicates that the radio is receiving in CSL state for platforms not supporting delayed
                               // reception.
+    uint16_t   mCslPeerShort; // The CSL peer short address.
     TimeMicro  mCslSampleTime;     // The CSL sample time of the current period.
     TimeMicro  mCslLastSync;       // The timestamp of the last successful CSL synchronization.
     uint8_t    mCslParentAccuracy; // Drift of timer used for scheduling CSL tx by the parent, in ± ppm.