USB 3.0 link layer timer adjustment to extend distance

摘要

Methods and devices for transmitting SuperSpeed information between a host device and a USB device via an extension medium are provided. Link partner relationships are established between the host device and an upstream facing port device, between the USB device and a downstream facing port device, and between the upstream facing port device and the downstream facing port device. While the link partner relationship between the upstream facing port device and the downstream facing port device is substantially compliant to the USB 3.0 Specification, the link partner relationship may use a configurable link layer acknowledgement timer to compensate for delays in transmission over the extension medium.

主权项

1. A Universal Serial Bus (USB) extension device, comprising:
a USB physical layer interface; a remote interface; and a protocol engine configured to:
establish a first link partner relationship with a device via the USB physical layer interface;establish a second link partner relationship with a second USB extension device via the remote interface;transmit a header packet received from the device via the USB physical layer interface to the second USB extension device via an extension medium accessible via the remote interface;receive a header packet acknowledgement from the second USB extension device;monitor the elapsed time between transmission of the header packet and receipt of the header packet acknowledgement using a configurable timer; andcause the second link partner relationship to transition to recovery in response to determining that the header packet acknowledgement has not been received within an elapsed time after the header packet transmission indicated by the configurable timer; wherein the header packet acknowledgement is received at an elapsed time after the header packet transmission that is greater than a standard link layer acknowledgement timer without causing the second link partner relationship or the first link partner relationship to transition to recovery; and wherein the configurable timer is set to a value greater than three microseconds.