Link State Machine for Hardware Software Power Coordination
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Solution Overview
Problem
Current power management in integrated circuits (ICs) faces challenges in efficiently managing power across functional units, particularly in mobile devices where battery life is a concern, as existing methods lack effective coordination between hardware and software power management to optimize power consumption and reduce latency in transactions.
Innovation Solution
The integration of a link state machine that monitors communications links between functional units, broadcasting availability and managing power states to ensure efficient clock gating and power gating, allowing for decentralized wake-ups and parallel power management across units, thereby optimizing power usage and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hardware power management is used to gate clock and power to functional units, then power consumption is reduced, but coordination with software power management becomes complex and latency increases
Solution Approach 1:
A link state machine acts as an intermediary between hardware and software power management components. It monitors communication links, determines when functional units are idle, and coordinates shutdown signals between hardware and software layers, simplifying the coordination complexity while enabling effective power gating.
Solution Approach 2:
The link state machine implements feedback mechanisms by continuously monitoring communication links and providing status information about functional unit activity. This feedback enables both hardware and software power management to make informed decisions about when to gate clock and power, reducing coordination complexity through automated status reporting.
2Loss of energy
If hardware power management shuts down functional units, then power consumption decreases, but wake-up latency increases
Solution Approach 1:
The link state machine performs preliminary monitoring of communication links to detect idle conditions before initiating power gating. By anticipating when functional units will be idle based on link status, the system can prepare for shutdown in advance, reducing the actual wake-up latency when activity is detected again.
Solution Approach 2:
The power management system dynamically adjusts shutdown and wake-up timing based on real-time link state monitoring. The link state machine enables flexible, condition-based power gating decisions rather than fixed timing, optimizing the balance between power savings and wake-up latency according to actual operational patterns.
3Adaptability or versatility
If software power management is used to monitor and control functional units, then flexibility is improved, but response time increases
Solution Approach 1:
The power management functionality is segmented into separate components: the link state machine handles rapid link monitoring and initial detection, while software power management handles higher-level coordination and decision-making. This segmentation allows the software to maintain flexibility while the hardware link state machine provides fast response to link changes.
Solution Approach 2:
The link state machine serves as an intermediary that bridges software power management flexibility with hardware response speed. It translates software power management decisions into rapid hardware actions and provides real-time link status feedback to software, enabling flexible yet responsive power management.
Data Source
AI summary
A method and apparatus for interfacing dynamic hardware power managed blocks and software power managed blocks is disclosed. In one embodiment, and integrated circuit (IC) may include a number of power manageable functional units. The functional units maybe power managed through hardware, software, or both. Each of the functional units may be coupled to at least one other functional unit through a direct communications link. A link state machine may monitor each of the communications links between functional units, and may broadcast indications of link availability to the functional units coupled to the link. Responsive to a software request to shut down a given link, or a hardware initiated shutdown of one of the functional units coupled to the link, the link state machine may broadcast and indication that the link is unavailable.