Thread partition merge mode TLV change (ARMmbed#1546)

When thread REED/Router device is sending parent request to higher partition,
it must set 'E' bit already in the first message.

Author: Tero Heinonen

source/6LoWPAN/Thread/thread_common.h

@@ -70,9 +70,9 @@ extern uint16_t thread_joiner_port;
 
 typedef enum {
     THREAD_STATE_NETWORK_DISCOVER,      // Not commissioned to Thread network
-    THREAD_STATE_REATTACH,              // Connected to thread network, searching for better partition
-    THREAD_STATE_REATTACH_RETRY,        // Connected to thread network, searching for better partition with REED bit is set
-    THREAD_STATE_ATTACH_ANY,            // Connected to thread network, searching for all partitions with leader connectivity
+    THREAD_STATE_REATTACH,              // Connection to leader lost, searching for new parent
+    THREAD_STATE_REATTACH_RETRY,        // Connection to leader lost, searching for new parent with REED bit is set
+    THREAD_STATE_ATTACH_ANY,            // Searching for all partitions with leader connectivity
     THREAD_STATE_CONNECTED,             // Attached to Thread network - can't route
     THREAD_STATE_CONNECTED_ROUTER,      // Attached to Thread network - Routing enabled
 } thread_attach_state_e;

source/6LoWPAN/Thread/thread_host_bootstrap.c

@@ -230,7 +230,9 @@ static int thread_parent_request_build(protocol_interface_info_entry_t *cur)
     }
 
     if (cur->thread_info->thread_attached_state == THREAD_STATE_REATTACH ||
-        cur->thread_info->thread_attached_state == THREAD_STATE_REATTACH_RETRY) {
+        cur->thread_info->thread_attached_state == THREAD_STATE_REATTACH_RETRY ||
+        cur->thread_info->thread_attached_state == THREAD_STATE_CONNECTED ||
+        cur->thread_info->thread_attached_state == THREAD_STATE_CONNECTED_ROUTER) {
         // When doing re-attach End devices are immediately accepted as parents
         scanMask |= 0x40;
     }