USB Type-C Vendor Defined Messaging Latency Tolerance
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Solution Overview
Problem
Existing information handling systems face challenges in managing latency and power management across devices that are daisy chained or use alternate modes of operation, particularly with devices like USB 2.0 and older types that do not support latency tolerance messages, leading to potential performance issues and power inefficiencies.
Innovation Solution
The system employs vendor-defined messaging for handling latency tolerance requirements through a side-band signal path, using a configuration channel to transmit vendor-defined messages (VDMs) from devices to the host, allowing for dynamic adjustment of latency settings based on connected devices' needs, thereby optimizing system performance and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If in-band latency tolerance messages (LTR/LTM) are used for latency management, then latency control is improved for devices that support them, but compatibility is lost with devices that do not support these messages (USB 2.0, audio devices, DisplayPort over USB2.0)
Solution Approach 1:
The patent introduces a side-band configuration channel as an intermediary communication path between host and device. This separate channel carries latency tolerance information independently from the data bus, allowing universal communication with all device types regardless of their native protocol support. The configuration channel acts as a mediator that translates and conveys latency requirements across incompatible interfaces.
Solution Approach 2:
The patent separates latency tolerance communication from the main data transmission path by using a dedicated configuration channel. This segmentation allows latency management to be handled independently through vendor-defined messages on the configuration channel, while data transmission continues uninterrupted on the original bus, resolving conflicts between protocol compatibility and latency control.
2Use of energy by stationary object
If the host enters sleep mode to reduce power consumption, then power efficiency is improved, but latency tolerance support may be disabled and remain disabled upon awakening
Solution Approach 1:
The patent stores latency tolerance values in persistent registers within the port controller before the host enters sleep mode. These pre-stored values ensure that when the host wakes up, the latency tolerance information is already available and does not need to be重新-negotiated, maintaining continuous support without requiring the device to remain active during sleep transitions.
Solution Approach 2:
The port controller autonomously maintains latency tolerance values in its internal registers without requiring continuous host intervention. The controller self-manages the storage and retrieval of these critical parameters, ensuring reliability persists through sleep/wake cycles without needing the host system actively managing latency settings.
3Device complexity
If standard latency messages are used for device communication, then protocol simplicity is maintained, but robustness is reduced for daisy-chained and hot-pluggable devices
Solution Approach 1:
The patent adds a new communication dimension by introducing a side-band configuration channel separate from the traditional data bus. This dimensional addition allows latency tolerance information to be transmitted through an alternative path that is specifically designed for configuration and control purposes, providing robustness for dynamic connection scenarios without complicating the original data transmission protocol.
Data Source
AI summary
A system and method for performing a latency tolerance operation, comprising: determining whether a host and a device coupled to a cable are both capable of communicating information regarding latency tolerance; identifying a host latency tolerance and a device latency tolerance; configuring the host and the device to communicate based upon the host latency tolerance and the device latency tolerance; and, communicating between the host and the device, the communicating conforming to the host latency tolerance and the device latency tolerance.