[mac] update ENABLE_BEACON_RSP_WHEN_JOINABLE behavior (#2147)

This commit updates the behavior of `ENABLE_BEACON_RSP_WHEN_JOINABLE`
feature. When this feature is enabled, the device will transmit IEEE
802.15.4 Beacons in response to IEEE 802.15.4 Beacon Requests even
while the device is not router-capable and detached.

src/core/mac/mac.cpp

@@ -1827,10 +1827,10 @@ otError Mac::HandleMacCommand(Frame &aFrame)
         mCounters.mRxBeaconRequest++;
         otLogInfoMac(GetInstance(), "Received Beacon Request");
 
-        if ((mBeaconsEnabled)
-#if OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
-            && (IsBeaconJoinable())
-#endif // OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
+        if (mBeaconsEnabled
+#if OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
+            || IsBeaconJoinable()
+#endif // OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
            )
         {
             StartOperation(kOperationTransmitBeacon);
@@ -1904,7 +1904,7 @@ void Mac::ResetCounters(void)
     memset(&mCounters, 0, sizeof(mCounters));
 }
 
-#if OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
+#if OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
 bool Mac::IsBeaconJoinable(void)
 {
     uint8_t numUnsecurePorts;
@@ -1923,7 +1923,7 @@ bool Mac::IsBeaconJoinable(void)
 
     return joinable;
 }
-#endif // OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
+#endif // OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
 
 Mac &Mac::GetOwner(const Context &aContext)
 {

src/core/mac/mac.hpp

@@ -587,16 +587,16 @@ public:
      */
     void ResetCounters(void);
 
-#if OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
+#if OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
     /**
-     * This method indicates if the beacon is joinable or non-joinable
+     * This method indicates if the device is in joinable state or not.
      *
-     * @retval true   Beacon is joinable.
-     * @retval false  Beacon is non-joinable.
+     * @retval true   Device is joinable.
+     * @retval false  Device is non-joinable.
      *
      */
     bool IsBeaconJoinable(void);
-#endif // OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
+#endif // OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
 
     /**
      * This method returns the MAC counter.

src/core/openthread-core-default-config.h

@@ -753,13 +753,16 @@
 #endif
 
 /**
- * @def OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
+ * @def OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
  *
- * Define to 1 if you want to enable beacon response for joinable networks.
+ * Define to 1 to enable IEEE 802.15.4 Beacons when joining is enabled.
+ *
+ * @note When this feature is enabled, the device will transmit IEEE 802.15.4 Beacons in response to IEEE 802.15.4
+ * Beacon Requests even while the device is not router capable and detached.
  *
  */
-#ifndef OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE
-#define OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_IF_JOINABLE         0
+#ifndef OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE
+#define OPENTHREAD_CONFIG_ENABLE_BEACON_RSP_WHEN_JOINABLE       0
 #endif
 
 /**