Modem Power State Transition via Cached Configuration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As computing systems become more complex, the power management in point-to-point interconnects, such as PCIe, faces challenges in balancing high performance with power efficiency, especially in mobile and IoT devices where traditional power states like D3cold offer significant power savings but require costly full initialization upon exit, limiting their applicability due to high reconfiguration overhead.
Innovation Solution
A modified inter-process communication protocol between the application processor and communications processor allows the modem to direct selection of low power states like D3cold based on modem-specific states or activity levels, and an enhanced D3 exit mechanism where the modem provides cached configuration data to the host, reducing reconfiguration overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional power states like D3cold are used to achieve significant power savings, then power consumption is reduced, but reconfiguration overhead increases due to costly full initialization upon exit
Solution Approach 1:
The patent applies preliminary action by having the communications processor prepare and cache configuration data before entering low power states. When exiting D3cold state, the pre-cached configuration data is already available, eliminating the need for full reinitialization. This advance preparation resolves the contradiction by reducing both power consumption (through deep sleep state) and reconfiguration overhead (through pre-cached data).
Solution Approach 2:
The patent uses copying by creating a cached copy of configuration data in the communications processor's memory before entering low power states. This copy allows rapid restoration without accessing external configuration sources, thereby reducing reconfiguration time and overhead while maintaining the ability to achieve deep power savings.
2Use of energy by moving object
If low power states are used frequently to extend battery life, then power efficiency improves, but system performance may degrade due to state transition overhead
Solution Approach 1:
By pre-caching configuration data before entering low power states, the system eliminates performance-degrading reinitialization overhead upon exit. This allows frequent transitions to low power states without sacrificing system performance, as the cached data enables rapid state restoration.
Solution Approach 2:
The communications processor serves itself by maintaining cached configuration data locally, eliminating the need for external configuration sources during state transitions. This self-service capability reduces transition overhead and allows frequent power state changes without performance degradation.
3Reliability
If full initialization is performed upon exiting D3cold state to ensure system reliability, then system stability is maintained, but power savings are reduced due to frequent reconfiguration
Solution Approach 1:
The patent performs preliminary action by caching configuration data before entering low power states. This pre-prepared data ensures system reliability upon exit without requiring full reinitialization, thereby maintaining stability while preserving power savings that would otherwise be lost to frequent reconfiguration cycles.
Solution Approach 2:
By creating and maintaining a cached copy of configuration data, the system ensures reliable operation upon exiting low power states without performing costly full initialization. This copy mechanism maintains system stability while enabling sustained power savings.
Data Source
AI summary
A modem identifies an idle condition associated with a data network to be accessed and determines an opportunity to enter a first one of a set of low power device states based on the idle condition, where the set of low power device states further includes a second low power device state, and a host device consumes less power in the first low power device state than in the second low power device state. A notification is sent to an application processor of the host device that the modem is to enter a sleep state, where the notification identifies the first low power device state, and a low power link state is entered corresponding to the first low power device state based on a signal from the application processor. The low power link state applies to a link coupling a communications processor of the modem to the application processor.