From 8fd8d1e0f968467ab986e43215e2aaec63b65bb6 Mon Sep 17 00:00:00 2001
From: rongli <rongli@nestlabs.com>
Date: Wed, 17 Apr 2019 01:28:14 +0800
Subject: [PATCH] [mle] enter fast poll mode when dequeue delayed MLE Data
 Request (#3761)

---
 src/core/thread/mle.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/core/thread/mle.cpp b/src/core/thread/mle.cpp
index 0ed752d3b..f59920e38 100644
--- a/src/core/thread/mle.cpp
+++ b/src/core/thread/mle.cpp
@@ -1840,6 +1840,16 @@ void Mle::HandleDelayedResponseTimer(void)
             if (SendMessage(*message, delayedResponse.GetDestination()) == OT_ERROR_NONE)
             {
                 LogMleMessage("Send delayed message", delayedResponse.GetDestination());
+
+                // Here enters fast poll mode, as for Rx-Off-when-idle device, the enqueued msg should
+                // be Mle Data Reqeuest.
+                // Note: Finer-grade check (e.g. message subtype) might be required when deciding whether
+                // or not enters fast poll mode fast poll mode if there are other type of delayed message
+                // for Rx-Off-when-idle device.
+                if (!IsRxOnWhenIdle())
+                {
+                    Get<DataPollManager>().SendFastPolls(DataPollManager::kDefaultFastPolls);
+                }
             }
             else
             {