添加注释

driver/src/hal/vfs_uart.c

@@ -1129,10 +1129,12 @@ int system_uart_deinit();
 int system_uart_init()
 {
     /* Get external port num. */
+    // 外置串口数目 目前是0
     uint8_t port = iot_board_get_external_uart_port_num();
     uart_info *p_uart_info = NULL;
     int i;
 
+    // 获得串口api
     g_uart_ctrl = uart_e_ctrl;
 
     g_uart_ext_num = (int)port;
@@ -1156,10 +1158,11 @@ int system_uart_init()
     os_mem_set(g_uart_rs485_port, 0x0,
         g_uart_rs485_num * sizeof(struct uart_rs485_ctrl));
 
+    // 初始化所有串口，设置中断回调函数，除了打印串口
     if (ERR_OK != uart_onchip_port_init(p_uart_info)) {
         goto error_out;
     }
-
+    // 外置串口数量为0 这里直接返回成功
     if (ERR_OK != uart_external_port_init(g_uart_ext_num,
         p_uart_info + IOT_UART_PORT_NUM_ONCHIP)) {
         goto error_out;