Dual-Mode PCIe Link Role Determination via Dynamic Mode Switching
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Solution Overview
Problem
In PCIe systems, multiple devices attempting to operate in root complex mode concurrently lead to link role collisions, as only one device can function in this mode, necessitating a method to dynamically determine and configure link roles to prevent collisions and ensure proper operation.
Innovation Solution
A dual-mode PCIe device with control circuitry that performs a configuration and initiation sequence on a wire-based PCIe link, invoking a random delay if unsuccessful, allowing it to switch to endpoint mode and enabling flexible configuration between root complex and endpoint modes based on the sequence's outcome.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple dual-mode PCIe devices are configured to operate in root complex mode concurrently, then device versatility and configuration flexibility are improved, but link role collisions occur because only one device can function as root complex
Solution Approach 1:
The patent implements dynamic role assignment where dual-mode PCIe devices can switch between root complex mode and endpoint mode based on configuration and initiation sequence outcomes. The control circuitry dynamically determines the link role by attempting configuration sequences and switching modes based on success or failure, allowing the system to adapt to different operational scenarios while preventing role collisions.
Solution Approach 2:
The patent changes the operational parameter of the PCIe device from a fixed mode to a variable mode. By modifying the device's operational state based on the configuration sequence results (successful or unsuccessful), the system allows devices to transition between root complex and endpoint roles, resolving the contradiction between versatility and collision prevention.
2Reliability
If a dual-mode PCIe device attempts configuration and initiation sequence in root complex mode, then proper link establishment is achieved, but time is lost due to random delay invocation when the sequence is unsuccessful
Solution Approach 1:
The patent performs preliminary configuration attempts in root complex mode before switching to endpoint mode. By attempting the configuration and initiation sequence first and only switching modes if unsuccessful, the system performs the necessary preparatory actions to establish proper link configuration while minimizing unnecessary mode switching and associated delays.
Solution Approach 2:
The system uses feedback from the configuration and initiation sequence outcomes to determine whether to remain in root complex mode or switch to endpoint mode. The control circuitry monitors the success or failure of configuration attempts and adjusts the operational mode accordingly, optimizing the balance between reliable link establishment and minimizing configuration time.
Data Source
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AI summary
Link role determination in a dual-mode Peripheral Component Interconnect express (PCIe) device is disclosed. In this regard, determining a link role for a dual-mode PCIe device involves configuring the dual-mode PCIe device to operate in a root complex (RC) mode or an endpoint mode. The dual-mode PCIe device first performs a configuration and initiation sequence on a wire-based PCIe link in the RC mode. If the configuration and initiation sequence on the wire-based PCIe link is unsuccessful, then the dual-mode PCIe device invokes a random delay and switches to the endpoint mode at expiration of the random delay. By determining a link role of the dual-mode PCIe device based on the configuration and initiation sequence, it is possible to configure dynamically the dual-mode PCIe device to operate in the RC mode or the endpoint mode, thus allowing flexible configuration of the dual-mode PCIe device based on various application scenarios.