control函数cmd不支持应该返回什么错误代码

发布于 2018-12-23 12:59:35 浏览：1412 订阅该版

* 本帖最后由 moss 于 2018-12-23 13:02 编辑 *

```static rt_err_t stm32_control(struct rt_serial_device *serial, int cmd, void *arg)
{
    struct stm32_uart *uart;
    rt_err_t ret = RT_EOK;

RT_ASSERT(serial != RT_NULL);

uart = (struct stm32_uart *)serial->parent.user_data;
    RT_ASSERT(uart != RT_NULL);

switch (cmd)
    {
    case RT_DEVICE_CTRL_CLR_INT:
        /* disable rx irq */
        NVIC_DisableIRQ(uart->irq);
        /* disable interrupt */
        __HAL_UART_DISABLE_IT(&uart->UartHandle, UART_IT_RXNE);
        break;

case RT_DEVICE_CTRL_SET_INT:
        /* enable rx irq */
        NVIC_EnableIRQ(uart->irq);
        /* enable interrupt */
        __HAL_UART_ENABLE_IT(&uart->UartHandle, UART_IT_RXNE);
        break;

#ifdef BSP_UART_USING_DMA_RX
    case RT_DEVICE_CTRL_CONFIG:
        if ((rt_ubase_t)arg == RT_DEVICE_FLAG_DMA_RX)
        {
            stm32_dma_config(serial);
        }
        break;
#endif
    default:
        ret = -RT_ERROR;
        break;
    }

return ret;
}```如上面函数，如果不是支持的 cmd 应该返回下面哪个错误代码？
```#define RT_ERROR                        1               /**< A generic error happens */

#define RT_ENOSYS                       6               /**< No system */

#define RT_EINVAL                       10              /**< Invalid argument */```