Virtual Link State Machines for Multi-Protocol Power Management
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Solution Overview
Problem
In multi-chip packages, the increasing bandwidth consumption and interconnect clocking frequency lead to lossy transmissions and errors, causing all communication protocol layers to be impacted during retraining, even if only one is active, resulting in inefficient power management and increased power consumption.
Innovation Solution
The implementation of virtual link state machines allows for independent link state management of each communication protocol layer, enabling synchronization only of active layers during retraining, while inactive layers remain in a low power state, using physical layer packets for communication and resolution tables to determine post-retraining link states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retraining is performed for all communication protocol layers when link errors occur, then link reliability is improved, but power consumption increases and power management efficiency deteriorates
Solution Approach 1:
The patent segments the link state management into multiple independent virtual link state machines, each corresponding to a specific communication protocol layer. This allows selective retraining of only the affected protocol layer(s) rather than forcing retraining of all layers, thereby maintaining link reliability while reducing unnecessary power consumption from idle layers.
Solution Approach 2:
The patent implements dynamic link state management where each virtual link state machine can independently transition between different link states (active, idle, low-power) based on the actual needs of each communication protocol layer. This dynamic approach allows the system to adapt power consumption levels to actual operational requirements while maintaining reliability where needed.
2Reliability
If retraining is performed for all communication protocol layers when link errors occur, then link reliability is improved, but power management efficiency deteriorates
Solution Approach 1:
The patent segments the link state management into multiple independent virtual link state machines, each corresponding to a specific communication protocol layer. This allows selective retraining of only the affected protocol layer(s) rather than forcing retraining of all layers, thereby maintaining link reliability while reducing unnecessary power consumption from idle layers.
Solution Approach 2:
Each virtual link state machine autonomously manages its own state transitions and participates in retraining only when necessary for its associated protocol layer. This self-service mechanism eliminates the need for centralized control to coordinate retraining across all layers, improving power management efficiency while maintaining reliability.
3Productivity
If virtual link state machines are implemented for independent link state management, then power management efficiency is improved, but device complexity increases
Solution Approach 1:
The patent implements virtual link state machines that serve multiple functions: they manage link states for different protocol layers, enable selective retraining, control power states, and maintain synchronization. This multi-functionality reduces the need for separate control mechanisms for each protocol layer, thereby improving power management efficiency without proportionally increasing device complexity.
Solution Approach 2:
The virtual link state machines act as intermediaries between the physical link layer and the multiple communication protocol layers. They abstract the complexity of independent link state management for each protocol layer, providing a unified interface that simplifies overall system complexity while enabling fine-grained power management.
Data Source
AI summary
In one embodiment, an apparatus includes an arbitration circuit with virtual link state machines to virtualize link states associated with multiple communication protocol stacks. The apparatus further includes a physical circuit coupled to the arbitration circuit and to interface with a physical link, where the physical circuit, in response to a retraining of the physical link, is to cause a plurality of the virtual link state machines to synchronize with corresponding virtual link state machines associated with a second side of the physical link, and where at least one of the communication protocol stacks is to remain in a low power state during the retraining and the synchronization. Other embodiments are described and claimed.