From 8b5833f7fed36a9dd3f1bf863ff52d8e92be2e27 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Tue, 9 Aug 2016 11:33:47 -0600
Subject: [PATCH] A consequence of Max's change to the logic to enable access
 to the backup domain is that every call to enabledbkp(true) must be followed
 by a matching call to enablebkp(false).  There was one cse in both RTCC
 drivers where that may not always be true.

---
 arch/arm/src/stm32/stm32_pwr.c        |  4 ++++
 arch/arm/src/stm32/stm32_rtcc.c       | 12 ++++++------
 arch/arm/src/stm32/stm32f40xxx_rtcc.c | 12 ++++++------
 3 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/arch/arm/src/stm32/stm32_pwr.c b/arch/arm/src/stm32/stm32_pwr.c
index dfe6df0751..8fb749f767 100644
--- a/arch/arm/src/stm32/stm32_pwr.c
+++ b/arch/arm/src/stm32/stm32_pwr.c
@@ -83,6 +83,10 @@ static inline void stm32_pwr_modifyreg(uint8_t offset, uint16_t clearbits, uint1
  *   Enables access to the backup domain (RTC registers, RTC backup data registers
  *   and backup SRAM).
  *
+ *   NOTE: Reference counting is used in order to supported nested calles to this
+ *   function.  As a consequence, every call to stm32_pwr_enablebkp(true) must
+ *   be followed by a call to stm32_pwr_enablebkp(false).
+ *
  * Input Parameters:
  *   writable - True: enable ability to write to backup domain registers
  *
diff --git a/arch/arm/src/stm32/stm32_rtcc.c b/arch/arm/src/stm32/stm32_rtcc.c
index 21e0441c06..d27a8ddd38 100644
--- a/arch/arm/src/stm32/stm32_rtcc.c
+++ b/arch/arm/src/stm32/stm32_rtcc.c
@@ -729,6 +729,12 @@ int up_rtc_initialize(void)
       /* Remember that the RTC is initialized */
 
       putreg32(RTC_MAGIC, RTC_MAGIC_REG);
+
+      /* Disable write access to the backup domain (RTC registers, RTC
+       * backup data registers and backup SRAM).
+       */
+
+      stm32_pwr_enablebkp(false);
     }
   else
     {
@@ -740,12 +746,6 @@ int up_rtc_initialize(void)
       rtc_dumpregs("Did resume");
     }
 
-  /* Disable write access to the backup domain (RTC registers, RTC backup
-   * data registers and backup SRAM).
-   */
-
-  stm32_pwr_enablebkp(false);
-
   if (ret != OK && nretry > 0)
     {
       rtcinfo("setup/resume ran %d times and failed with %d\n",
diff --git a/arch/arm/src/stm32/stm32f40xxx_rtcc.c b/arch/arm/src/stm32/stm32f40xxx_rtcc.c
index 5b1f244977..cbd136d6d5 100644
--- a/arch/arm/src/stm32/stm32f40xxx_rtcc.c
+++ b/arch/arm/src/stm32/stm32f40xxx_rtcc.c
@@ -1028,6 +1028,12 @@ int up_rtc_initialize(void)
       /* Remember that the RTC is initialized */
 
       putreg32(RTC_MAGIC, RTC_MAGIC_REG);
+
+      /* Disable write access to the backup domain (RTC registers, RTC
+       * backup data registers and backup SRAM).
+       */
+
+      stm32_pwr_enablebkp(false);
     }
   else
     {
@@ -1039,12 +1045,6 @@ int up_rtc_initialize(void)
       rtc_dumpregs("Did resume");
     }
 
-  /* Disable write access to the backup domain (RTC registers, RTC backup
-   * data registers and backup SRAM).
-   */
-
-  stm32_pwr_enablebkp(false);
-
   if (ret != OK && nretry > 0)
     {
       rtcinfo("setup/resume ran %d times and failed with %d\n",