From 9c6293759a9c9c076e46aeac5689d72f675436b2 Mon Sep 17 00:00:00 2001
From: Silvano Seva <silseva@fastwebnet.it>
Date: Sun, 12 May 2024 12:23:09 +0200
Subject: [PATCH] Fix boot for CKS32F407 when -Os is used

---
 .../mcu/CMSIS/Device/ST/STM32F4xx/Source/system_stm32f4xx.c     | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/platform/mcu/CMSIS/Device/ST/STM32F4xx/Source/system_stm32f4xx.c b/platform/mcu/CMSIS/Device/ST/STM32F4xx/Source/system_stm32f4xx.c
index 010a9009..e25a15b7 100644
--- a/platform/mcu/CMSIS/Device/ST/STM32F4xx/Source/system_stm32f4xx.c
+++ b/platform/mcu/CMSIS/Device/ST/STM32F4xx/Source/system_stm32f4xx.c
@@ -312,6 +312,8 @@ static void SetSysClock(void)
   {
     /* Select regulator voltage output Scale 1 mode, System frequency up to 168 MHz */
     RCC->APB1ENR |= RCC_APB1ENR_PWREN;
+    __DSB();
+
     PWR->CR |= PWR_CR_VOS;
 
     /* HCLK = SYSCLK / 1 */