Root Port Resume Time Module for Dynamic Recovery
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Solution Overview
Problem
Current computing systems face challenges in achieving rapid resume times for root ports and root port integrated endpoints, leading to delays in device configuration and increased power consumption due to fixed minimum recovery times, which are not device-specific and can be undesirable in certain contexts.
Innovation Solution
The implementation of a resume time module that allows devices to advertise their specific recovery times and enables interrupt mechanisms for internal devices to trigger configuration access before the completion of power state transitions, reducing the need for fixed wait times and optimizing power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed minimum recovery time is enforced for power state transitions, then device stability and reliability are improved, but resume time and system performance deteriorate
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed, static recovery time to a dynamic, device-specific recovery time. The root complex determines the recovery time based on the specific device's capabilities and requirements, allowing the system to adapt the recovery time rather than using a one-size-fits-all fixed value. This resolves the contradiction by enabling faster resume times for devices that can handle them while maintaining sufficient stability for devices that require longer recovery periods.
Solution Approach 2:
The patent changes the parameter of recovery time from a fixed constant to a variable parameter that can be adjusted based on device-specific characteristics. By allowing the root complex to determine appropriate recovery times for different devices, the system optimizes the balance between reliability and resume time performance, avoiding unnecessary delays for devices capable of faster recovery.
2Reliability
If a fixed minimum recovery time is enforced for power state transitions, then device stability is improved, but power consumption increases due to extended wait times
Solution Approach 1:
The dynamic determination of recovery time based on device-specific requirements allows the system to minimize power consumption by avoiding unnecessarily long wait states. Devices that can recover quickly do not impose extended power-draining delays on the system, while still maintaining adequate recovery time for devices that require it for stability.
Solution Approach 2:
The patent applies partial action by implementing recovery times that are sufficient for each specific device's needs rather than uniformly applying an excessive fixed minimum time to all devices. This eliminates wasted energy from overly conservative recovery periods while maintaining necessary stability for each device type.
3Productivity
If interrupt mechanisms are implemented for configuration access, then productivity and resume speed are improved, but device complexity increases
Solution Approach 1:
The interrupt mechanism implements feedback by allowing the device to signal when it is ready for configuration access after a power state transition. This active notification system eliminates the need for polling or fixed wait times, enabling the root complex to immediately proceed with configuration when the device indicates readiness, thus improving productivity with manageable complexity.
Data Source
AI summary
A serial point-to-point link interface to enable communication between a processor and a device, the high speed serial point-to-point link interface including a transmitter to transmit serial data, a receiver to deserialize serial data, and control logic to implement a protocol stack. The protocol stack supports a plurality of power management states, including an active state, a first off state, in which a supply voltage is maintained, and a second off state, in which the supply voltage is not to be provided to the device. The protocol stack provides a default recovery time to allow the device to begin a transition from the first off state to the active state prior to accessing the device. The protocol stack further provides for accessing the device prior to expiration of the default recovery time to complete the transition based on a device-advertised recovery time.