On-Die System Fabric Sideband Segments Power Management
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Solution Overview
Problem
Resetting and powering down subsets of components in an integrated circuit device can lead to operational issues or loss of flexibility, as it may cause the remaining subsets to become non-operational or error-prone, especially when messages are in progress, and simultaneous resetting of all components can result in loss of partial operational capabilities.
Innovation Solution
The implementation of an On-Die System Fabric (OSF) sideband network segmented into separate power domains, with a Power Management Controller (PMC) managing the reset process by ensuring all messages are completed before resetting a sideband segment, using PREP and reset warn flows to handle in-progress messages and transition the network to an idle state, allowing for graceful power management across different power domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If subsets of components are reset and powered down in isolation, then power consumption is reduced, but the remaining subsets become non-operational or error-prone
Solution Approach 1:
The sideband network is divided into multiple independently controllable segments, each associated with specific subsets of components. This segmentation allows individual segments to be reset and powered down without affecting the operational status of other segments, resolving the contradiction between power reduction and system reliability.
2Loss of energy
If all component subsets are reset and powered down simultaneously, then power consumption is reduced, but the integrated circuit loses flexibility and partial operational capability
Solution Approach 1:
By dividing the sideband network into multiple segments that can be independently controlled, the system enables selective power management. Different segments can be powered down based on operational requirements, maintaining flexibility and partial operational capability while still achieving power consumption reduction when needed.
Solution Approach 2:
The power management system dynamically adjusts the power state of different segments based on real-time operational requirements. The PMC can transition segments between active and powered-down states independently, allowing the system to adapt its power consumption profile while maintaining necessary operational flexibility.
3Loss of energy
If a sideband segment is reset while messages are in progress, then power management is achieved, but deadlocks and operational errors occur
Solution Approach 1:
The PMC implements preliminary actions by detecting in-progress messages and initiating completion protocols before resetting a sideband segment. The system waits for all messages to be completed or aborted before transitioning the segment to a powered-down state, preventing deadlocks and ensuring message transfer integrity while still achieving power management goals.
Solution Approach 2:
The system employs feedback mechanisms where the PMC continuously monitors the state of messages in progress within each segment. Based on this feedback, the PMC determines the appropriate timing for segment reset, ensuring that power management actions are taken only when it is safe to do so, thereby maintaining reliability.
Data Source
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AI summary
Methods and apparatus for managing sideband segments in an On-Die System Fabric (OSF) are described. In one embodiment, a sideband OSF includes a plurality of segments that may be reset or powered down independently after power management logic determines that in progress messages have been handled and future messages to the segment being reset or powered down will be blocked. Other embodiments are also disclosed.