void RCC_Configuration(void)
{
  /* RCC system reset(for debug purpose) */
  RCC_DeInit();

/* Enable HSE */
  RCC_HSEConfig(RCC_HSE_ON);

/* Wait till HSE is ready */
  HSEStartUpStatus = RCC_WaitForHSEStartUp();

if(HSEStartUpStatus == SUCCESS)
  {
        
    /* Enable Prefetch Buffer */
    FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
....

...

前面几步是一个DeInit再Init的过程.

可以观察寄存器的状态看是否Init成功: