Stream Context Cache System for USB Data Transfer

Solution Overview

Problem

Conventional USB systems experience time delays and increased power consumption due to repetitive readings of stream contexts from system memory, leading to inefficiencies in data transfer.

Innovation Solution

A stream context cache system that includes a cache for storing pre-fetched stream contexts, a mapping table with valid bits, and a conversion table using a HASH function to index stream context addresses, allowing direct retrieval from the cache instead of system memory.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the host controller reads stream context from system memory whenever data is transferred, then data transfer can be maintained, but time delay and power consumption increase

Engineering Contradiction:

Improvedata transfer efficiencyVSAvoidread time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The system pre-fetches stream contexts into the cache before they are needed for data transfer. The host controller proactively loads stream contexts into the cache memory in advance, so that when data transfer is required, the stream context is already available in the cache rather than needing to be read from system memory at the moment of need. This preliminary action eliminates the read time delay and reduces power consumption associated with frequent memory reads.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the host controller reads stream context from system memory whenever data is transferred, then data transfer can be maintained, but power consumption increases

Engineering Contradiction:

Improvedata transfer efficiencyVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The system pre-fetches stream contexts into the cache before they are needed for data transfer. The host controller proactively loads stream contexts into the cache memory in advance, so that when data transfer is required, the stream context is already available in the cache rather than needing to be read from system memory at the moment of need. This preliminary action eliminates the read time delay and reduces power consumption associated with frequent memory reads.

Inventive Principle:

Principle #10Preliminary action

3Loss of time

If a cache system is introduced to store stream contexts, then read time is reduced, but device complexity increases

Engineering Contradiction:

Improveread timeVSAvoidsystem structure

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent introduces a cache memory as an intermediary component between the host controller and system memory. The cache acts as a mediator that stores frequently accessed stream contexts, allowing the host controller to read from the cache rather than directly from system memory. This intermediary approach reduces read time while the complexity is managed through a straightforward cache architecture with valid bits and hash indexing, keeping the added complexity minimal and manageable.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8645630B2Stream context cache system

Publication Date: 2014.02.04 VIA TECH INC

AI summary

The present invention is directed to a stream context cache system, which primarily includes a cache and a mapping table. The cache stores plural stream contexts, and the mapping table stores associated stream context addresses in a system memory. Consequently, a host may, according to the content of the mapping table, directly retrieve the stream context that is pre-fetched and stored in the cache, rather than read the stream context from the system memory.