在sys目录下找到对应的控制器
例如：/sys/devices/platform/soc/ehci，直接操作该目录下的companion
echo 1 > companion 将port1设置为companion控制器所有，即降速
echo -1 > companion
/*
* Dedicate or undedicate a port to the companion controller.
* Syntax is "[-]portnum", where a leading '-' sign means
* return control of the port to the EHCI controller.
*/