Abstract: A method and apparatus for reclaiming bus bandwidth on a full duplex bus. A source node sends a primary packet toward a destination node along a full duplex bus. If the destination node identifies an inability to accept the primary packet, it sends a NAK in the opposite direction along the full duplex bus towards the source node. Upon receiving the NAK, the source node aborts packet transmission of the primary packet which by virtue of the NAK has been identified as futile. Accordingly, the bandwidth, which would have otherwise have been used for the futile packet transmission, can be reclaimed and used for some other purpose.

Abstract: Distributed arbitration in a full-duplex bus system. By distributing the arbitration function among the nodes of a tree topology full-duplex bus system such that arbitration at any particular time is handled by a node holding a grant of the bus at that time (the nominal root node), a reverse flow direction towards the nominal root node is available for arbitration flow. This allows the discrete arbitration phase to be eliminated and generally improves bus efficiency.

Abstract: A method and apparatus for early arbitration in a full duplex bus system. Early arbitration in a distributed arbitration serial bus system permits the resolution of requests for a next fairness interval during a current fairness interval such that the grant of the highest priority request in the next fairness interval may immediately follow a last packet of a last subaction in a current fairness interval. In this way, the bandwidth previously wasted propagating an arbitration reset token and waiting for arbitration requests can be substantially eliminated.

Abstract: Distributed arbitration in a full-duplex bus system. By distributing the arbitration function among the nodes of a tree topology full-duplex bus system such that arbitration at any particular time is handled by a node holding a grant of the bus at that time (the nominal root node), a reverse flow direction towards the nominal root node is available for arbitration flow. This allows the discrete arbitration phase to be eliminated and generally improves bus efficiency.

Abstract: Distributed arbitration in a full-duplex bus system. By distributing the arbitration function among the nodes of a tree topology full-duplex bus system such that arbitration at any particular time is handled by a node holding a grant of the bus at that time (the nominal root node), a reverse flow direction towards the nominal root node is available for arbitration flow. This allows the discrete arbitration phase to be eliminated and generally improves bus efficiency.

Abstract: A method and apparatus of improving serial bus efficiency. Improvement of bus efficiency through the reduction of enforced subaction gaps can be accomplished by attaching an explicit end of subaction (EOS) token to packets that are the last packet of a subaction. The EOS should be selected to be an encoding that is not easily confused with any encoding used for normal data encoding. The presence of the EOS token permits arbitration to begin without waiting for a subaction gap after the EOS token is seen on the bus. Additionally, it permits fly by concatenation with packets containing an EOS token. In some cases multiple concatenations are possible. Because the EOS token is independent of subaction type, this technique expands readily as new subactions are developed. Employing the features overall bus efficiency can be increased.

Abstract: A method for hindering a first type of node from becoming an arbitration controller during a tree identification process is described. The method includes sending a first request from a first node to a second node. The response to the first request is delayed by establishing a parent-child relationship between a third node and the second node, the second and third nodes being the first type of node. A response is then sent, establishing the second node as the child of the first node. Afterward, the first node is designated as the bus arbitration controller.

Abstract: A method and apparatus for early arbitration in a full duplex bus system. Early arbitration in a distributed arbitration serial bus system permits the resolution of requests for a next fairness interval during a current fairness interval such that the grant of the highest priority request in the next fairness interval may immediately follow a last packet of a last subaction in a current fairness interval. In this way, the bandwidth previously wasted propagating an arbitration reset token and waiting for arbitration requests can be substantially eliminated.

Abstract: An arbitration method for access to a serial bus includes the steps of monitoring for the presence of an arbitration reset gap on the serial bus, and arbitrating for an access, if needed, upon recognizing the presence of an arbitration reset gap on the serial bus. The method further comprises the steps of determining if immediately arbitrating for an additional access without waiting for the presence of another arbitration reset gap on the serial bus is authorized, upon successfully arbitrating for an access. If immediately arbitrating for an additional access is authorized, and the additional access is needed, arbitration for the additional access is immediately made. A method for controlling arbitration for access to a serial bus includes the step of programming bus agents with information for the bus agents to determine whether immediately arbitrating for additional accesses to the serial bus are authorized.