Reset-Domain Bridge Handshake for Pending Packet Responses
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Solution Overview
Problem
In data processing systems with multiple reset domains, asserting a reset in one domain without simultaneously resetting the transport network can lead to data loss and protocol violations due to unresponded packets, causing deadlocks and inefficiencies.
Innovation Solution
Implementing bridge circuitry to communicate transport packets, packet tracking circuitry to monitor responses, and reset handling circuitry to ensure all required responses are provided before allowing a reset in a given domain, using a handshake process to manage resets and prevent deadlocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reset is asserted in a specific reset domain while the transport network continues operating, then data processing circuitry can be reset without affecting the entire system, but unresponded transport packets may cause deadlocks and protocol violations
Solution Approach 1:
The system performs preliminary actions by tracking transport packets before the reset is actually asserted. The packet tracking circuitry monitors incoming packets and identifies which ones require responses, preparing the system in advance to handle reset scenarios properly and prevent deadlocks.
Solution Approach 2:
The system implements feedback mechanisms where the packet tracking circuitry continuously monitors the state of transport packets and provides information to the reset handling circuitry. This feedback loop ensures that reset decisions are made based on the current packet state, preventing protocol violations and deadlocks.
2Reliability
If all transport packets are responded to before resetting a domain, then deadlocks are prevented, but system productivity decreases due to waiting time
Solution Approach 1:
The system applies partial action by tracking only the specific transport packets that require responses, rather than waiting for all possible packets. The reset handling circuitry determines when sufficient responses have been received to safely proceed with the reset, balancing reliability with productivity.
Solution Approach 2:
The system changes the parameter of packet tracking from tracking all packets to tracking only those requiring responses. This parameter change optimizes the balance between preventing deadlocks and maintaining productivity by reducing unnecessary waiting time.
3Adaptability or versatility
If the transport network operates in a different reset domain than data processing circuitry, then selective resetting is enabled, but data loss occurs when packets are transmitted across reset domain boundaries
Solution Approach 1:
The bridge circuitry acts as an intermediary between the transport network and data processing circuitry operating in different reset domains. It manages packet transmission across the reset domain boundary, ensuring proper handling and preventing data loss when resets occur in one domain while the other continues operating.
Solution Approach 2:
The system segments the system into different reset domains, allowing independent resetting of data processing circuitry while the transport network continues operating. The bridge circuitry manages the interface between these segmented domains, preventing data loss during asymmetric reset operations.
Data Source
AI summary
An apparatus has bridge circuitry to communicate transport packets between a transport network and data processing circuitry. Some or all of the data processing circuitry operates in a given reset domain other than the reset domain of the transport network. The apparatus also has packet tracking circuitry to monitor the transport packets received at the bridge circuitry and to track whether any required responses have been provided. The reset handling circuitry is responsive to a reset request for the given reset domain to: cause the bridge circuitry to reject new transport packets received for the domain; and when the packet tracking circuitry indicates that all required responses have been provided, accept the reset request for the given reset domain and allow the data processing circuitry to carry out a reset for the data processing circuitry operating in the given reset domain.