Open-Drain Output for Distinct Memory Signaling Interfaces
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Solution Overview
Problem
Existing memory subsystem initialization processes are inefficient due to lack of handshaking between the system memory controller and memory modules, leading to unnecessary delays and inefficiencies, particularly in configurations like LR-DIMM where the memory subsystem controller's completion time is unknown to the system memory controller.
Innovation Solution
Implementing a notification signaling interface using an open-drain output for the memory subsystem controller to indicate completion of initialization sequences, allowing the system memory controller to execute independent commands and reducing wait times by providing immediate feedback on task completion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system memory controller waits for unknown completion time of memory subsystem controller during initialization, then initialization can be completed, but unnecessary delays and inefficiencies occur
Solution Approach 1:
The patent implements a feedback mechanism where the memory subsystem controller sends completion notifications to the system memory controller via an open-drain output interface. This allows the system memory controller to immediately know when initialization sequences are complete, eliminating unnecessary waiting periods while ensuring reliable initialization completion.
2Productivity
If no handshaking interface is implemented between system memory controller and memory subsystem controller, then device complexity is reduced, but productivity during initialization is reduced
Solution Approach 1:
The patent reuses the existing open-drain output interface (originally designed for parity error indication during normal operations) to also carry initialization completion notifications. This multi-functional use of the existing interface improves initialization productivity without adding new hardware complexity, as the same physical interface serves dual purposes depending on the operational mode.
3Device complexity
If the open-drain output is used for both parity error indication and initialization status signaling, then device complexity is minimized, but signaling reliability for distinct operations may be compromised
Solution Approach 1:
The patent dynamically switches the function of the open-drain output based on the operational mode. During normal operations, the interface indicates parity errors; during initialization operations, it signals completion status. This dynamic reconfiguration allows a single interface to reliably serve distinct purposes without signal confusion, as the system knows which signaling mode is active at any given time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the complexity and time required for system memory controller interactions during initialization by enabling immediate notification of task completion, thereby enhancing the overall efficiency of the initialization process.
Implementation Method 1
The memory subsystem controller has an open drain output and is configured to provide a first signaling interface via the open drain output during normal operations and a second signaling interface via the open drain output during an initialization operation
Data Source
AI summary
A memory subsystem is operable with a memory controller of a host computer system via an interface. The memory subsystem comprises dynamic random access memory elements and a memory subsystem controller. The memory subsystem controller has an open drain output, and is configured to provide a first signaling interface via the open drain output during normal operations and a second signaling interface via the open drain output during an initialization operation. The second signaling interface is distinct from the first signaling interface and the initialization operation is distinct from any of the normal operations. The first signaling interface is used by the memory subsystem controller to indicate a parity error in response to a parity error having occurred during the normal operations. The second signaling interface is used by the memory subsystem controller to output a signal related to initialization operation sequences during the initialization operation.