Time Synchronization Between Independent Processors
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Solution Overview
Problem
Time synchronization between independently operable processors is complex due to different power and time domains, lack of a clear master-slave relationship, and variations in clock frequencies caused by manufacturing tolerances and low power modes, leading to issues in media playback and data processing accuracy.
Innovation Solution
A method and apparatus for synchronizing time references between independently operable processors involve suspending a coordinated state machine, transacting time measurements, and determining clock differences using inter-processor communication links, with mechanisms to capture timestamps and adjust clock rates to ensure accurate timing alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If independently operable processors use separate internal oscillators for timekeeping, then each processor can operate autonomously without master-slave dependency, but clock frequency variations due to manufacturing tolerances and power mode transitions cause time synchronization errors
Solution Approach 1:
The patent implements a feedback mechanism where processors exchange timestamp information through the IPC link to measure clock drift. Each processor records timestamps of received messages and calculates the difference between its local clock and the remote processor's clock. This feedback information is used to adjust timing operations and compensate for frequency variations, maintaining synchronization accuracy while preserving processor autonomy.
Solution Approach 2:
The patent dynamically adjusts timing parameters based on measured clock drift. By monitoring the frequency differences between processors and changing timing compensation parameters in real-time, the system adapts to manufacturing variations and power mode transitions, resolving the contradiction between autonomous operation and synchronization accuracy.
2Use of energy by moving object
If processors operate in low power modes independently, then energy consumption is reduced, but clock frequency changes during power mode transitions cause timing misalignment
Solution Approach 1:
The feedback mechanism continuously monitors clock drift even during power mode transitions. When a processor enters or exits low power mode, the IPC link exchanges timestamp information that captures the timing impact of the transition. This feedback allows the other processor to compensate for the frequency changes, maintaining timing alignment while allowing independent power management.
Solution Approach 2:
The system performs preliminary timing measurements and establishes baseline clock relationships before power mode transitions occur. By pre-characterizing the frequency behavior of processors in different power states, the system can apply appropriate compensation factors during transitions, ensuring timing reliability while enabling energy-efficient operation.
3Adaptability or versatility
If no clear master-slave relationship is defined, then processors can flexibly perform different functions, but time reference coordination becomes complex and difficult to manage
Solution Approach 1:
Instead of imposing a traditional master-slave hierarchy, the patent inverts the approach by treating both processors as equal peers that independently maintain their own time references. Each processor actively participates in synchronization by exchanging timestamps and calculating drift, transforming the complexity from hierarchical control to symmetric collaboration. This maintains functional flexibility while distributing the synchronization management burden.
Solution Approach 2:
Each processor independently measures its own clock drift relative to the other processor and autonomously adjusts its timing operations. The synchronization mechanism is self-service in that processors don't rely on external master control but rather on mutual information exchange and self-correction, reducing management complexity while preserving functional versatility.
Data Source
AI summary
Methods and apparatus for synchronization of time between independently operable processors. Time synchronization between independently operable processors is complicated by a variety of factors. For example, neither independently operable processor controls the other processor's task scheduling, power, or clocking. In one exemplary embodiment, a processor can initiates a time synchronization process by disabling power state machines and transacting timestamps for a commonly observed event. In one such embodiment, timestamps may be transferred via inter-processor communication (IPC) mechanisms (e.g., transfer descriptors (TDs), and completion descriptors (CDs)). Both processors may thereafter coordinate in time synchronization efforts (e.g., speeding up or slowing down their respective clocks, etc.).