diff --git NuttX/nuttx/drivers/usbdev/cdcacm.c NuttX/nuttx/drivers/usbdev/cdcacm.c
index 64e2e68..15f92dd 100644
--- NuttX/nuttx/drivers/usbdev/cdcacm.c
+++ NuttX/nuttx/drivers/usbdev/cdcacm.c
@@ -243,6 +243,12 @@ static const struct uart_ops_s g_uartops =
 #ifdef CONFIG_SERIAL_IFLOWCONTROL
   cdcuart_rxflowcontrol, /* rxflowcontrol */
 #endif
+#ifdef CONFIG_SERIAL_DMA
+  NULL,                  /* dmasend */
+  NULL,                  /* dmareceive */
+  NULL,                  /* dmarxfree */
+  NULL,                  /* dmatxavail */
+#endif
   NULL,                  /* send */
   cdcuart_txint,         /* txinit */
   NULL,                  /* txready */
diff --git NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c
index 644c810..10919e8 100644
--- NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c
+++ NuttX/nuttx/arch/arm/src/stm32/stm32_serial.c
@@ -1945,11 +1945,11 @@ static int up_interrupt_common(struct up_dev_s *priv)
 static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
 {
 #if defined(CONFIG_SERIAL_TERMIOS) || defined(CONFIG_SERIAL_TIOCSERGSTRUCT) \
-    || defined(CONFIG_STM32F7_SERIALBRK_BSDCOMPAT)
+    || defined(CONFIG_STM32_SERIALBRK_BSDCOMPAT)
   struct inode      *inode = filep->f_inode;
   struct uart_dev_s *dev   = inode->i_private;
 #endif
-#if defined(CONFIG_SERIAL_TERMIOS) || defined(CONFIG_STM32F7_SERIALBRK_BSDCOMPAT)
+#if defined(CONFIG_SERIAL_TERMIOS) || defined(CONFIG_STM32_SERIALBRK_BSDCOMPAT)
   struct up_dev_s   *priv  = (struct up_dev_s *)dev->priv;
 #endif
   int                ret    = OK;
diff --git NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_rcc.c NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_rcc.c
index 5e2ba73..adda863 100644
--- NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_rcc.c
+++ NuttX/nuttx/arch/arm/src/stm32/stm32f40xxx_rcc.c
@@ -95,10 +95,10 @@ static inline void rcc_reset(void)
 
   putreg32(0x00000000, STM32_RCC_CFGR);
 
-  /* Reset HSION, HSEON, CSSON and PLLON bits */
+  /* Reset HSEON, CSSON and PLLON bits */
 
   regval  = getreg32(STM32_RCC_CR);
-  regval &= ~(RCC_CR_HSION | RCC_CR_HSEON | RCC_CR_CSSON | RCC_CR_PLLON);
+  regval &= ~(RCC_CR_HSEON | RCC_CR_CSSON | RCC_CR_PLLON);
   putreg32(regval, STM32_RCC_CR);
 
   /* Reset PLLCFGR register to reset default */
@@ -619,11 +619,6 @@ static void stm32_stdclockconfig(void)
   volatile int32_t timeout;
 
 #ifdef STM32_BOARD_USEHSI
-  /* Enable Internal High-Speed Clock (HSI) */
-
-  regval  = getreg32(STM32_RCC_CR);
-  regval |= RCC_CR_HSION;           /* Enable HSI */
-  putreg32(regval, STM32_RCC_CR);
 
   /* Wait until the HSI is ready (or until a timeout elapsed) */
 
diff --git NuttX/nuttx/arch/arm/src/stm32/stm32_flash.c NuttX/nuttx/arch/arm/src/stm32/stm32_flash.c
index 73f1419..9ac38a1 100644
--- NuttX/nuttx/arch/arm/src/stm32/stm32_flash.c
+++ NuttX/nuttx/arch/arm/src/stm32/stm32_flash.c
@@ -231,12 +231,14 @@ ssize_t up_progmem_erasepage(size_t page)
       return -EFAULT;
     }
 
-  /* Get flash ready and begin erasing single page */
-
+#if !defined(CONFIG_STM32_STM32F40XX)
   if (!(getreg32(STM32_RCC_CR) & RCC_CR_HSION))
     {
       return -EPERM;
     }
+#endif
+
+  /* Get flash ready and begin erasing single page */
 
   stm32_flash_unlock();
 
@@ -318,12 +320,14 @@ ssize_t up_progmem_write(size_t addr, const void *buf, size_t count)
       return -EFAULT;
     }
 
-  /* Get flash ready and begin flashing */
-
+#if !defined(CONFIG_STM32_STM32F40XX)
   if (!(getreg32(STM32_RCC_CR) & RCC_CR_HSION))
     {
       return -EPERM;
     }
+#endif
+
+  /* Get flash ready and begin flashing */
 
   stm32_flash_unlock();