From f5577c005e744fc0df7d13870339d73f4037067e Mon Sep 17 00:00:00 2001
From: jeromecoutant <jerome.coutant@st.com>
Date: Fri, 16 Nov 2018 14:32:32 +0100
Subject: [PATCH] STM32 RTC : skip rtc_write if possible

---
 targets/TARGET_STM/rtc_api.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/targets/TARGET_STM/rtc_api.c b/targets/TARGET_STM/rtc_api.c
index 798ce29bb1..a4c45a9cdf 100644
--- a/targets/TARGET_STM/rtc_api.c
+++ b/targets/TARGET_STM/rtc_api.c
@@ -217,6 +217,11 @@ void rtc_write(time_t t)
     RTC_DateTypeDef dateStruct = {0};
     RTC_TimeTypeDef timeStruct = {0};
 
+    /* if the requested time is the current time, no need to continue */
+    if (t == rtc_read()) {
+        return;
+    }
+
     core_util_critical_section_enter();
     RtcHandle.Instance = RTC;