PCIe Completion Timeout Reporting for Error Identification
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Solution Overview
Problem
In PCIe systems, a Completion Timeout (CTO) occurs when a PCIe End Point fails to respond timely, leading to a System Error (SError) that causes the entire system to go offline without providing information on the offending transaction or Master.
Innovation Solution
The implementation of a PCIe configuration space capability called CTOR (Completion Timeout Reporting) that stores the CTO address and the Master ID of the Master that issued the transaction. This information is used to identify the problematic transaction and avoid or terminate it, preventing a complete system failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Completion Timeout (CTO) is issued by the PCIe controller when a PCIe End Point fails to respond timely, then the system can detect the error condition, but the system goes offline with no information available about which transaction address caused the CTO or which Master issued the transaction
Solution Approach 1:
The patent applies preliminary action by capturing and storing the transaction address and Master ID in a FIFO buffer at the moment a Completion Timeout occurs, before the system shuts down. This allows the error information to be preserved for later analysis. The FIFO buffer is pre-configured to hold this critical information, ensuring it is captured immediately when the timeout condition is detected.
Solution Approach 2:
The patent introduces an intermediary mechanism - a dedicated FIFO buffer and control register interface - that mediates between the PCIe controller's error detection and the system's error reporting needs. This intermediary structure captures the transaction address and Master ID, then makes this information accessible to software through a controlled interface, preventing information loss while maintaining system stability.
2Reliability
If the system shuts down completely when an SError occurs, then the error condition is handled conservatively to prevent further damage, but no diagnostic information is available to users or developers
Solution Approach 1:
The patent extracts the critical diagnostic information (transaction address and Master ID) from the error condition and stores it in a separate, accessible location (FIFO buffer). This allows the system to maintain stability and continue operating while the extracted error information can be independently analyzed by software, separating the diagnostic data collection from the system shutdown response.
Solution Approach 2:
The patent implements feedback by providing a mechanism where software can read the stored error information from the FIFO buffer through a control register interface. This creates a feedback loop where error information is not only captured but also returned to the software for analysis, enabling debugging and corrective actions without requiring a complete system shutdown.
3Productivity
If multiple Masters can issue transactions through the PCIe controller, then the system achieves high productivity and resource utilization, but it becomes impossible to identify which specific Master caused a Completion Timeout
Solution Approach 1:
The patent applies segmentation by capturing and storing the Master ID as a separate identifier associated with each transaction address in the FIFO buffer. This segmentation of transaction identification into distinct components (Master ID and transaction address) allows the system to handle multiple Masters simultaneously while maintaining the ability to trace and identify the specific source of each Completion Timeout error.
Data Source
AI summary
A method to retrieve transaction address resulting in PCIe completion timeout includes monitoring a Peripheral Component Interconnect Express (PCIe) controller to detect a Completion Timeout (CTO) transmitted therefrom. A Master Identification (ID) of a Master and a transaction address of a transaction are stored in a configuration space, in response to detecting the CTO, wherein the transaction originates from the Master and the CTO is signaled in response to the transaction. The CTO is responded to with the Master identified by the Master ID in the configuration space.