Processor Power Mode Transition Interrupt Handling
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Solution Overview
Problem
Existing power-saving techniques in processor-based systems, such as software-based save-restore methods, fail to respond to interrupt events during transitions between active and power-down modes, leading to delays, lost interrupts, and energy overhead, while requiring significant design changes and not providing comprehensive restoration of read-only registers.
Innovation Solution
A method that transitions between active and power-down modes through intermediate states, allowing detection and response to interrupt events during state saving, masking and unmasking of interrupts, and software restoration of read-only registers without major hardware design changes, ensuring timely handling and order preservation of interrupts and complete state restoration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If software-based save-restore technique is used for power saving, then power consumption is reduced, but interrupt events cannot be responded to during transition
Solution Approach 1:
The transition process is divided into multiple intermediate states (first intermediate state, second intermediate state) rather than a single direct transition. This segmentation allows the system to check for interrupt events at specific checkpoints during the transition, enabling interrupt response while maintaining power-saving benefits.
Solution Approach 2:
The system performs preliminary actions by checking for interrupt events before completing the power-down transition. The interrupt status is detected in advance during intermediate states, allowing the system to prepare for interrupt handling without compromising the power-saving transition.
2Use of energy by stationary object
If transition between active and power-down mode is initiated, then power saving is achieved, but interrupt events are masked or lost
Solution Approach 1:
The system implements feedback mechanisms where interrupt status is continuously monitored and checked during the transition process. The interrupt flag is checked at multiple points (first intermediate state, second intermediate state), providing feedback that allows the system to detect and handle interrupt events without losing information.
3Ease of manufacture
If scan-based save-restore technique is used, then state saving is achieved, but design changes and high current drain are required
Solution Approach 1:
The system uses self-service mechanisms where the existing processor architecture and memory are utilized for state saving without requiring external scan chains or complex hardware interfaces. The processor itself manages the save-restore process using its own registers and memory resources, eliminating the need for additional hardware infrastructure.
4Loss of time
If high-speed scan shifting is used for state saving, then save-restore time is minimized, but current drain increases
Solution Approach 1:
The system performs partial state saving operations only when necessary, checking interrupt events at specific intermediate states rather than continuously. This partial action approach reduces the overall time and energy consumption compared to continuous high-speed scan shifting, while still achieving acceptable save-restore performance.
Data Source
AI summary
A method of transitioning between an active mode and a power-down mode in a processor-based system includes saving a state of the active mode, detecting the occurrence of one or more interrupt events during a transition between the active mode and the power-down mode, and responding to the detected interrupt events.