Because driver maintains connection to both nodes while write transactions are directed to the primary node, read transactions can be directed to either node.
由于驱动程序维护与两个节点的连接，同时写事务被定向到主节点，因此读事务可以定向到任何一个节点。
2
The device descriptor read by the host controller driver contains information about the device, such as class, subclass, and protocol.