Wakeup Interrupt Controller for Power Saving and Interrupt Retention

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Solution Overview

Problem

Data processing systems face issues with losing pending interrupts or events when entering a low power state, as existing software-based solutions create race conditions and may result in information loss due to power reduction or removal.

Innovation Solution

A hardware-based approach using a wakeup interrupt controller (WIC) that transfers pending interrupts from active-time storage to sleep-time storage before entering a low power state and back to active-time storage upon receiving a wakeup signal, ensuring uninterrupted event handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If processing circuitry enters a low power state to reduce power consumption, then power savings are achieved, but pending interrupt indications are lost

Engineering Contradiction:

Improvepower consumptionVSAvoidpending interrupt indications

Core Design Contradiction:

Use of energy by moving objectVSLoss of information

Solution Approach 1:

The patent extracts the storage function for pending interrupt indications from the processing circuitry itself and places it in a separate wakeup interrupt controller. This allows the processing circuitry to enter low power states while the WIC remains active and retains interrupt information, resolving the contradiction between power savings and information retention.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The wakeup interrupt controller acts as an intermediary between external interrupt sources and the processing circuitry. It stores interrupt indications during low power states and transfers them back to active-time storage when the processing circuitry wakes up, preventing information loss while enabling power savings.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of information

If software-based solutions are used to save pending interrupts before entering low power state, then information loss is reduced, but race conditions occur and reliability decreases

Engineering Contradiction:

Improvepending interrupt indicationsVSAvoidinterrupt handling reliability

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The patent replaces software-based interrupt saving mechanisms with a hardware-based wakeup interrupt controller. This hardware solution automatically captures and retains interrupt indications without requiring software intervention, eliminating race conditions and improving reliability while preventing information loss.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The wakeup interrupt controller is pre-configured with sleep-time storage specifically designed to hold pending interrupt indications before the processing circuitry enters low power state. This preliminary preparation ensures that interrupts are captured reliably without requiring software to perform saving operations at the right moment.

Inventive Principle:

Principle #10Preliminary action

3Loss of information

If processing circuitry maintains active state to preserve interrupt information, then information integrity is maintained, but power consumption increases

Engineering Contradiction:

Improvepending interrupt indicationsVSAvoidpower consumption

Core Design Contradiction:

Loss of informationVSUse of energy by moving object

Solution Approach 1:

The patent segments the interrupt handling functionality into two separate components: the processing circuitry that performs data processing operations and the wakeup interrupt controller that manages interrupt storage. This segmentation allows the processing circuitry to enter low power state while the WIC maintains interrupt information, achieving both power savings and information preservation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a copy of the interrupt indication storage function in the wakeup interrupt controller. Instead of maintaining the original storage in the processing circuitry during low power state, a duplicate storage mechanism is established in the WIC, allowing the processing circuitry to power down while interrupt information is preserved in the copied storage location.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS11226828B2Wakeup interrupt controller

Publication Date: 2022.01.18 ARM LTD

AI summary

Apparatuses comprising data processing circuitry and a wakeup interrupt controller and methods of operating the apparatuses are disclosed. Prior to the processing circuitry entering a low power state, indications of pending interrupts are transferred to the wakeup interrupt controller. Further indications of interrupts received whilst the processing circuitry is in the low power state may be accumulated in the wakeup interrupt controller. When the wakeup interrupt controller receives a wakeup signal, the indications of pending interrupts are transferred to the processing circuitry and the processing circuitry exits the low power state.