From bac6d8c85df9d3856505bd4295d908ef4706c8b7 Mon Sep 17 00:00:00 2001
From: Yakun Xu <xyk@google.com>
Date: Thu, 2 Apr 2020 09:09:22 +0800
Subject: [PATCH] [mac] remove disable CSMA-CA on the last transmit (#4765)

---
 src/core/config/mac.h                         | 10 ----------
 .../config/openthread-core-config-check.h     | 11 ++++-------
 src/core/mac/sub_mac.cpp                      | 19 +------------------
 3 files changed, 5 insertions(+), 35 deletions(-)

diff --git a/src/core/config/mac.h b/src/core/config/mac.h
index 26c6ecd99..ae7798b29 100644
--- a/src/core/config/mac.h
+++ b/src/core/config/mac.h
@@ -172,16 +172,6 @@
 #define OPENTHREAD_CONFIG_MAC_TX_NUM_BCAST 1
 #endif
 
-/**
- * @def OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT
- *
- * Define as 1 to disable CSMA-CA on the last transmit attempt.
- *
- */
-#ifndef OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT
-#define OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT 0
-#endif
-
 /**
  * @def OPENTHREAD_CONFIG_MAC_STAY_AWAKE_BETWEEN_FRAGMENTS
  *
diff --git a/src/core/config/openthread-core-config-check.h b/src/core/config/openthread-core-config-check.h
index 506b0d628..2338fcf1a 100644
--- a/src/core/config/openthread-core-config-check.h
+++ b/src/core/config/openthread-core-config-check.h
@@ -59,9 +59,11 @@
  *
  */
 
-#ifdef OPENTHREAD_CONFIG_DISABLE_CCA_ON_LAST_ATTEMPT
+#if defined(OPENTHREAD_CONFIG_DISABLE_CCA_ON_LAST_ATTEMPT) ||     \
+    defined(OPENTHREAD_CONFIG_DISABLE_CSMA_CA_ON_LAST_ATTEMPT) || \
+    defined(OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT)
 #error \
-    "OPENTHREAD_CONFIG_DISABLE_CCA_ON_LAST_ATTEMPT was replaced by OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT."
+    "OPENTHREAD_CONFIG_DISABLE_CCA_ON_LAST_ATTEMPT, OPENTHREAD_CONFIG_DISABLE_CSMA_CA_ON_LAST_ATTEMPT and OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT were removed."
 #endif
 
 #ifdef OPENTHREAD_CONFIG_MAX_TX_ATTEMPTS_DIRECT
@@ -394,11 +396,6 @@
 #error "OPENTHREAD_CONFIG_ENABLE_DYNAMIC_MPL_INTERVAL was replaced by OPENTHREAD_CONFIG_MPL_DYNAMIC_INTERVAL_ENABLE."
 #endif
 
-#ifdef OPENTHREAD_CONFIG_DISABLE_CSMA_CA_ON_LAST_ATTEMPT
-#error \
-    "OPENTHREAD_CONFIG_DISABLE_CSMA_CA_ON_LAST_ATTEMPT was replaced by OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT."
-#endif
-
 #ifdef OPENTHREAD_CONFIG_ENABLE_LONG_ROUTES
 #error "OPENTHREAD_CONFIG_ENABLE_LONG_ROUTES was replaced by OPENTHREAD_CONFIG_MLE_LONG_ROUTES_ENABLE."
 #endif
diff --git a/src/core/mac/sub_mac.cpp b/src/core/mac/sub_mac.cpp
index e84fc4f8b..54e600cc2 100644
--- a/src/core/mac/sub_mac.cpp
+++ b/src/core/mac/sub_mac.cpp
@@ -231,14 +231,6 @@ void SubMac::StartCsmaBackoff(void)
 
     VerifyOrExit(ShouldHandleCsmaBackOff(), BeginTransmit());
 
-#if OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT
-    if ((mTransmitRetries > 0) && (mTransmitRetries == mTransmitFrame.GetMaxFrameRetries()))
-    {
-        BeginTransmit();
-        ExitNow();
-    }
-#endif
-
     if (backoffExponent > kMaxBE)
     {
         backoffExponent = kMaxBE;
@@ -274,16 +266,7 @@ void SubMac::BeginTransmit(void)
 
     VerifyOrExit(mState == kStateCsmaBackoff);
 
-#if OPENTHREAD_CONFIG_MAC_DISABLE_CSMA_CA_ON_LAST_ATTEMPT
-    if ((mTransmitRetries > 0) && (mTransmitRetries == mTransmitFrame.GetMaxFrameRetries()))
-    {
-        mTransmitFrame.SetCsmaCaEnabled(false);
-    }
-    else
-#endif
-    {
-        mTransmitFrame.SetCsmaCaEnabled(true);
-    }
+    mTransmitFrame.SetCsmaCaEnabled(true);
 
     if ((mRadioCaps & OT_RADIO_CAPS_SLEEP_TO_TX) == 0)
     {