PCIe Endpoint Device Discovery via Ready Status Bit
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Solution Overview
Problem
Current PCIe endpoint device discovery methods unnecessarily delay the initialization process by requiring software or firmware to wait a minimum time after power-on or reset, leading to suboptimal user experience and inefficient system operation.
Innovation Solution
An endpoint device discovery system that includes a downstream port with a register to set an endpoint ready status bit in response to an endpoint ready message, allowing software to determine when the endpoint device is ready for configuration, thereby enabling immediate access and configuration once the device is initialized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software or firmware waits a minimum time (100ms per PCIe spec, typically 1 second) after power-on or reset before attempting to poll or access PCIe endpoint devices, then the PCIe endpoint device initialization is ensured to be complete, but the endpoint device discovery process is unnecessarily slowed down and user experience is degraded
Solution Approach 1:
The patent implements a feedback mechanism where the PCIe endpoint device actively signals its readiness status to the IHS through an endpoint ready message. The IHS monitors this feedback signal and only initiates polling or access operations when the device confirms it is ready, eliminating the need for fixed waiting periods while ensuring initialization completion.
Solution Approach 2:
The PCIe endpoint device performs self-service by autonomously generating and sending an endpoint ready message when its initialization is complete. This self-signal mechanism allows the device to control its own availability status, eliminating the need for the IHS to use conservative fixed timeouts or polling intervals.
2Reliability
If the IHS uses fixed waiting periods (100ms minimum, 1 second typical) before accessing PCIe endpoint devices, then initialization errors are prevented, but system efficiency and boot time are reduced
Solution Approach 1:
The system replaces fixed waiting periods with a feedback-based readiness detection mechanism. The PCIe endpoint device sends an endpoint ready message when initialization is complete, allowing the IHS to reliably determine when the device is ready for access without using inefficient fixed timeouts, thereby improving both reliability and productivity.
Solution Approach 2:
The patent changes the parameter for determining device readiness from a fixed time-based approach (100ms minimum, 1 second typical) to a state-based approach using the endpoint ready message. This parameter change allows the system to adapt to actual device initialization speed rather than using conservative fixed intervals.
3Adaptability or versatility
If the IHS implements traditional PCIe endpoint device discovery methods with fixed waiting periods, then compatibility with existing PCIe specifications is maintained, but the actual initialization requirements of many PCIe endpoint devices (which need much less time) are not met
Solution Approach 1:
The patent performs preliminary action by having the PCIe endpoint device send its endpoint ready message during the initialization process itself, before the IHS needs to access the device. This allows the IHS to prepare for optimal access timing without waiting for fixed periods, while still maintaining compatibility with the PCIe specification framework.
Solution Approach 2:
The system maintains compatibility with PCIe specifications while improving performance by using the endpoint ready message as a feedback mechanism. This feedback signal is generated in accordance with PCIe initialization procedures but enables the IHS to access the device immediately when ready, rather than using fixed waiting periods.
Data Source
AI summary
An endpoint device discovery system includes a downstream port. A register is coupled to the downstream port. An endpoint ready status bit may be set in the register in response to an endpoint ready message received at the downstream port. A non-transitory computer-readable medium is coupled to the register and includes computer-readable instructions that, when executed by a processor, cause the processor to determine that the endpoint ready status bit is set and, in response, configure an endpoint device that is coupled to the downstream port. The endpoint device discovery system may be included in an information handling system (IHS) in order to provide for discovery of endpoint devices that are coupled to the IHS as soon as those endpoint devices have initialized.