PCIe Tx EQ Coefficient Reuse for Faster Link-Up
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Solution Overview
Problem
The process of exchanging coefficient values to achieve a desired bit error rate during link-up in PCIe systems is time-consuming and wastes system resources.
Innovation Solution
Reusing previously determined coefficient values for downstream port transmission equilibrium when both upstream and downstream devices have not changed, eliminating the need for repeated coefficient exchanges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coefficient values are exchanged during link-up to achieve desired BER, then link reliability is improved, but link-up time increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal channel setup values in a lookup table before link-up occurs. When a link-up event happens, the controller retrieves pre-computed coefficients based on channel characteristics rather than performing real-time calculations or exchanges, thus ensuring reliability through optimized values while dramatically reducing link-up time.
2Manufacturing precision
If coefficient exchange process is performed during link-up, then channel optimization is achieved, but system resources are wasted
Solution Approach 1:
The system performs channel optimization work in advance by pre-calculating optimal coefficients and storing them in a lookup table. This preliminary action eliminates the need for resource-intensive real-time coefficient exchanges during link-up, maintaining channel optimization quality while conserving system resources during actual operation.
Solution Approach 2:
The patent uses copying by creating a lookup table that stores pre-computed optimal channel setup values. Instead of performing complex calculations or exchanges during link-up, the system copies relevant pre-computed values from the lookup table based on channel characteristics, achieving channel optimization with minimal resource consumption.
3Adaptability or versatility
If repeated coefficient exchanges are performed during each link-up, then adaptability to channel changes is maintained, but link-up speed decreases
Solution Approach 1:
The system prepares adaptability in advance by pre-calculating optimal coefficients for various channel conditions and storing them in a lookup table. During link-up, the controller quickly retrieves the appropriate pre-computed values based on detected channel characteristics, maintaining adaptability to different channel conditions while achieving fast link-up speeds without repeated exchanges.
Data Source
AI summary
The present disclosure generally relates to reducing link-up time between an upstream device and a downstream device. Rather than re-coordinating the link between devices each time, knowledge gained from a previous link-up is used to speed up the link-up. Typically, when both the upstream device and the downstream device have not changed, then the coefficient values for downstream port (DSP) transmission (Tx) equilibrium (EQ) that resulted in a desired bit error rate (BER) should not have changed either. Hence, rather than exchanging coefficients, the previous values can be reused with confidence eliminating the need to exchange coefficients. In so doing, the link-up process is much faster and system resources are not wasted on unnecessary coefficient exchanges.