Serial Interconnect Test Logic for Sub-Segment Fault Reporting
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Solution Overview
Problem
Current loopback testing methods in high-speed serial communications are inadequate for identifying and locating faults, especially in links with extension devices like repeaters and retimers, as they cannot determine error directions and do not provide mechanisms for error detection and reporting during normal operations, leading to potential link degradation and lack of proactive retraining.
Innovation Solution
Implementing an extended loopback testing mechanism where each transmitter sends a predetermined pattern, allowing receivers to detect errors and report them through enhanced SKP ordered sets or CRC/parity bits, enabling error identification and reporting during both test and normal operations, and allowing retimers to request link retraining if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional loopback testing is used, then testing can be performed, but fault location and error direction identification are not possible
Solution Approach 1:
The link is divided into multiple link sub-segments, with each sub-segment having its own reporting message and status region. This segmentation allows each receiver to report errors specific to its incoming link sub-segment, enabling precise fault location and direction identification.
Solution Approach 2:
A feedback mechanism is implemented where each receiver sends reporting messages back to the upstream component, containing status information about errors detected in its incoming link sub-segment. This feedback loop enables continuous monitoring and identification of error locations and directions.
2Length of stationary object
If extension devices like repeaters and retimers are added to extend link distance, then communication range is improved, but fault identification and error reporting capability deteriorates
Solution Approach 1:
The link is divided into multiple link sub-segments separated by extension devices. Each sub-segment has dedicated reporting messages that allow errors to be pinpointed to specific segments, making fault detection easier despite the presence of multiple extension devices.
Solution Approach 2:
Extension devices act as intermediaries that not only extend the link but also serve as error detection points. Each extension device monitors its incoming and outgoing sub-segments and reports errors through dedicated status regions in reporting messages.
3Measurement precision
If error reporting mechanism is added to identify fault locations, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The reporting message structure and status regions are designed to serve multiple functions: error detection, fault location, direction identification, and link health monitoring. This multi-functionality reduces the need for separate testing mechanisms, thereby limiting complexity increase.
4Reliability
If link testing is performed during normal operations, then link health monitoring is improved, but communication throughput may be affected
Solution Approach 1:
Error reporting is performed periodically through dedicated reporting messages sent at regular intervals during normal operations. This periodic monitoring maintains link health awareness while minimizing impact on continuous data communication throughput.
Data Source
AI summary
An apparatus that includes a serial interconnect is provided, wherein the serial interconnect includes test logic to send a number of reporting messages, wherein each reporting message is associated with a link sub-segment in a link in the serial interconnect, and each reporting message comprises a status region for the associated link sub-segment to report transmission errors. The test logic also includes analysis logic to record errors in the link sub-segment.