NVMe Hot-Plug Reset Stability via Clock Monitoring
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Solution Overview
Problem
Conventional hot-plugging techniques for NVMe storage devices result in issues such as premature reset time expiration, lane reversal problems, and non-deterministic states due to sequential engagement of pins and unstable reference clock de-assertion, leading to reduced throughput and usability.
Innovation Solution
An Information Handling System (IHS) with a processing system that includes a memory system with instructions to enter a reset state upon a hot-plug event, monitor the reference clock for stability, and only exit the reset state and de-assert the reset pin after a predetermined stable period, ensuring proper initialization and operation of NVMe storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional hot-plugging techniques are used for NVMe storage devices, then the device can be connected without shutting down the system, but the sequential engagement of pins causes premature reset expiration and lane reversal problems
Solution Approach 1:
The patent applies preliminary action by extending the reset state duration to ensure all communication lanes are engaged before the device exits reset. This preliminary extension prevents premature reset expiration that occurs with conventional hot-plugging, allowing the device to wait until all pins are properly connected before becoming operational.
Solution Approach 2:
The patent uses feedback by monitoring the engagement status of communication lanes to determine when to exit the reset state. The device continuously checks whether all lanes are properly connected and only transitions from reset when this condition is satisfied, ensuring reliable operation based on actual connection status.
2Reliability
If the reset time is extended to wait for all pins to engage, then device operation stability improves, but the device initialization time increases
Solution Approach 1:
The patent applies dynamics by making the reset state duration adaptive rather than fixed. The reset extension lasts only as long as necessary for all communication lanes to engage, dynamically adjusting the initialization period based on actual connection speed and requirements, thus minimizing unnecessary time loss while ensuring stability.
3Speed
If the securing latch is rotated quickly to activate the securing subsystem, then the hot-plug operation speed increases, but sequential pin engagement causes lane reversal and operational issues
Solution Approach 1:
The patent applies preliminary action by maintaining the reset state as a preparatory condition that prevents premature operation. Even though the securing latch rotates quickly, the device remains in reset until all lanes are engaged, ensuring proper communication lane configuration is established before the device becomes operational.
Data Source
AI summary
A device hot-plug system includes a chassis. A connector is included in the chassis. A reset pin is included on the connector. A hot-plug device is configured, in response to being hot-plugged to the connector, to enter a device reset state. While in the device reset state, the hot-plug device monitors a reference clock and determines that the reference clock has been stable for a predetermined time period. In response to determining that the reference clock has been stable for a predetermined time period, the hot-plug device exits the device reset state and provides a de-assertion signal on the reset pin.