Underrun Detector for Display Controller Buffer Monitoring
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Solution Overview
Problem
Existing display control units fail to provide effective diagnostic information to address underrun conditions, leading to improper display of image data due to bandwidth limitations and latency issues, despite previous solutions attempting to mitigate these issues.
Innovation Solution
A diagnostic data generation apparatus and method within a system-on-chip device that includes an underrun detector and diagnostic data registers to monitor FIFO buffers, record location data of underruns, and generate diagnostic data to identify and potentially rectify the cause of underruns, allowing for real-time or subsequent remedial action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If image data is retrieved from memory and stored in buffers at a predetermined frame rate, then the display controller can drive the display unit at the required update frequency, but the memory bandwidth limitations cause underrun conditions where buffers lack image data for processing
Solution Approach 1:
The patent applies preliminary action by implementing an underrun detector that proactively monitors buffer data levels before underrun conditions occur. The detector continuously checks whether the number of pixels in the FIFO buffer is less than a predetermined threshold, enabling early detection and response to potential underrun conditions before they affect display output.
Solution Approach 2:
The patent implements feedback by creating a closed-loop monitoring system where the underrun detector continuously monitors buffer status and generates underrun information that can be used to adjust memory access timing and rates. This feedback mechanism allows the system to adapt memory bandwidth allocation based on actual buffer consumption patterns, preventing underrun conditions while maintaining high display update frequencies.
2Productivity
If the display controller continues to drive the display unit using empty buffers during underrun conditions, then the display operation is maintained, but the display unit fails to display properly the image data intended for display
Solution Approach 1:
The underrun detector provides continuous feedback on buffer status, enabling the system to distinguish between legitimate empty buffers (which should trigger underrun conditions) and buffers that are temporarily empty during normal operation. This feedback allows the display controller to maintain operation continuity while preventing quality degradation by detecting and responding to true underrun conditions.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the predetermined threshold value based on buffer depth and display requirements. By changing this parameter, the system can optimize the balance between maintaining display operation continuity and preventing display quality degradation, allowing flexible adaptation to different operating conditions.
3Reliability
If existing display control units use simple underrun mitigation techniques such as supplying previous pixels or averaging, then display operation is maintained, but no useful diagnostic information is provided to identify or rectify the cause of underruns
Solution Approach 1:
The patent introduces an intermediary diagnostic data register that captures and stores underrun information including the state of the FIFO buffer and timing data at the moment an underrun condition is detected. This intermediary structure preserves critical diagnostic information that would otherwise be lost, enabling subsequent analysis of underrun causes while maintaining display operation stability through the underrun detector's monitoring functions.
Solution Approach 2:
The patent applies copying by creating a duplicate record of the buffer state and timing information in the diagnostic data register whenever an underrun condition occurs. This copy preserves the exact conditions leading to the underrun, allowing developers to analyze and rectify the root cause without affecting the ongoing display operation or losing critical diagnostic details.
4Adaptability or versatility
If memory priorities serve other host units, then those units receive adequate bandwidth, but the memory cannot fill the buffers at the rate required by the display controller
Solution Approach 1:
The underrun detector creates a feedback loop that monitors the actual buffer fill rate versus the required display rate. When underrun conditions indicate that the buffer fill rate is insufficient, this feedback information can be used to adjust memory access timing, prioritize display-related memory transactions, or trigger alerts that enable real-time optimization of memory resource allocation between the display controller and other host units.
Data Source
AI summary
A diagnostic data generation apparatus for a display controller comprises an underrun detector arranged to monitor, when in use, buffer depletion in order to detect an underrun condition. The underrun condition results from a data feed lag associated with a mismatch between a buffer fill rate and a predetermined output data rate. The underrun detector is arranged to generate diagnostic data in response to detection of the underrun condition, the diagnostic data identifying the underrun condition and a location in an array of pixels associated with the underrun condition.