USB 3.0 Device Re-enumeration via LTSSM State Transition

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Solution Overview

Problem

Current USB 3.0 implementation lacks a specification-compliant method for re-enumeration, which is essential for updating device configurations and maintaining compatibility with multiple devices connected to a single port, leading to potential performance issues and lack of standardized procedures.

Innovation Solution

A method is introduced that involves establishing a connection with a host, transmitting an indicator to cause the Link Training and Status State Machine to transition, synchronizing with the host, and presenting a new device configuration, effectively emulating a disconnection and reconnection to induce re-enumeration, ensuring compatibility with USB 3.0 standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If USB 3.0 devices use standard connection methods, then compatibility is maintained, but re-enumeration capability is lost

Engineering Contradiction:

Improvere-enumeration capabilityVSAvoidconnection stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The device preemptively transitions to SS.Inactive state and sends a indicator signal to the host before actual re-enumeration is needed, preparing the connection state in advance to enable seamless re-enumeration without disrupting ongoing operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary state machine (LTSSM) transition sequence as a mediator between the device and host, using state transitions (U0→SS.Inactive→RX.Detect→U0) to enable controlled re-enumeration while maintaining connection stability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If devices emulate disconnection to trigger re-enumeration, then configuration updates are enabled, but connection disruption occurs

Engineering Contradiction:

Improveconfiguration update capabilityVSAvoidconnection re-establishment time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The device uses periodic state transitions in the LTSSM (alternating between U0, SS.Inactive, and RX.Detect states) to rhythmically trigger re-enumeration, enabling configuration updates through controlled connection fluctuations without prolonged disruption

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Instead of the host initiating re-enumeration through traditional disruption methods, the device inverts the approach by actively transitioning to SS.Inactive state and sending indicators to the host, reversing the conventional initiation direction to enable smoother configuration updates

Inventive Principle:

Principle #13The other way round (Inversion)

3Quantity of substance

If multiple devices share a USB port, then device density increases, but performance becomes sluggish

Engineering Contradiction:

Improvedevice densityVSAvoiddata transmission speed

Core Design Contradiction:

Quantity of substanceVSProductivity

Solution Approach 1:

The device monitors connection state and uses feedback from the host's response to indicator signals to dynamically adjust enumeration behavior, enabling performance optimization based on real-time system conditions when multiple devices share the USB port

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9864607B2Methods and physical computer-readable storage media for initiating re-enumeration of USB 3.0 compatible devices

Publication Date: 2018.01.09 INFINEON TECHNOLOGIES AMERICAS CORP

AI summary

Methods, physical computer-readable media, and devices are provided that allow re-enumeration to be initiated on a USB 3.0-compatible device. The method includes establishing a connection with a host, transmitting an indicator from the device to the host to cause a Link Training and Status State Machine (LTSSM) of the host to move from active state (U0) to one of SS.Inactive and RX.Detect, synchronizing the device with the host, and presenting a new configuration of the device to the host.