USBHOST rt_usb_get_interface_descriptor 有点小BUG

发布于 2013-06-16 14:26:11 浏览：2773 订阅该版

```rt_err_t rt_usb_get_interface_descriptor(ucfg_desc_t cfg_desc, int num, 
    uintf_desc_t* intf_desc)
{
	rt_err_t ret;
    rt_uint32_t ptr, depth = 0;
    udesc_t desc;

/* check parameter */
    RT_ASSERT(cfg_desc != RT_NULL);

ptr = (rt_uint32_t)cfg_desc + cfg_desc->bLength;
    while(ptr < (rt_uint32_t)cfg_desc + cfg_desc->wTotalLength)
    {
        if(depth++ > 0x20) 
        {
            *intf_desc = RT_NULL;        
            return -RT_EIO;
        }
        desc = (udesc_t)ptr;
        if(desc->type == USB_DESC_TYPE_INTERFACE)
        {
            if(((uintf_desc_t)desc)->bInterfaceNumber == num)
            {
                *intf_desc = (uintf_desc_t)desc;

RT_DEBUG_LOG(RT_DEBUG_USB,
                             ("rt_usb_get_interface_descriptor: %d
", num));
				
//                 return RT_EOK;
				ret = RT_EOK;
				
				//有的接口描述符端点数为0,需继续查找接口
				if(((uintf_desc_t)desc)->bNumEndpoints > 0)
					break;
            }
        }    
        ptr = (rt_uint32_t)desc + desc->bLength;
    }

//     rt_kprintf("rt_usb_get_interface_descriptor %d failed
", num);
//     return -RT_EIO;
	if(ret != RT_EOK)
		rt_kprintf("rt_usb_get_interface_descriptor %d failed
", num);
    return ret;
}```
注释的是原来的，有的USB设备接口描述符同个接口有两个或多个描述符，但只有一个有端点数，其它端点数为0（可能是厂商自定义的）：原代码识别不了，改了后可以了