Lsi Logic Corporation

Lsi Corporation

David A Thomas

Fataneh F Ghodrat

Judy M Gehman

Christopher D Paulson

David O Sluiter

Timothy D Thompson

Mark Buchanan

Michael R Stein

A method for discarding perpetually-rejected packets in a fabric-based interconnect having a reliable physical layer is disclosed. A transmitting component keeps a count of the number of negative acknowledgements (NAKs) it receives from the receiving component for packets the transmitting component sends. If the transmitting component receives a number of consecutive NAKs for the same packet that exceeds some pre-determined threshold, the packet is not resent, but is, instead, treated as having been acknowledged, and subsequent packets are allowed to be transmitted. Higher-level processes are then notified of the problem so as to allow the error to be dealt with at a higher level, but without obstructing the flow of packets on the physical layer.

Method for discarding corrupted data packets in a reliable transport fabric

A hardware-controlled data protection scheme can be used on a device providing buffering between two different protocols, especially where at least one of the protocols does not use fixed length blocks. A fixed block size is arbitrarily imposed on the data in order to calculate a cyclical redundancy code (CRC) for the block. Block sizes are restricted to a value of 2, e.g., 2, 4, 8, 16, etc. The device is able to time-share and to receive or send data on more than one port while sharing the CRC engine between the ports. Intermediate values of the CRC for a given port are temporarily saved in a CRC register file. As a block of data for a given port is completed, a final CRC value for the block is saved to a CRC random access memory (RAM) located on the device and the entry in the register file is cleared. When the data is then output from the device, the CRC for the block is recalculated and checked against the saved value to be sure that they match.

CRC data protection scheme for non-block-oriented data

Isochronous data transfers guarantee data packets are received at a particular frequency and within a prespecified jitter-tolerance. Asynchronous data transfers guarantee data integrity by allowing missed or errant packets to be resent as many times as needed until an error-free packet may be reconstructed at the receiver. Isochronous transfers address real-time needs but do not address the data integrity issue. Asynchronous transfers address the data integrity issue but cannot guarantee error-free data packets will be available so as to meet a real-time constraint. The present invention provides method and apparatus enable isochronous data transfers with improved data integrity. Various link layer and transaction layer mechanisms are taught. An embodiment involving the IEEE 1394 bus specification is addressed in detail.

Method and apparatus for isochronous data transfer with retry capability

A method and apparatus for processing data packets through direct memory access (DMA) in transferring data packets between a bus and an apparatus containing DMA engines. The DMA engines process different contexts, also referred to as distinct logical data streams. The phase of a bus along with the status of DMA transactions are monitored. The phase and the status are used to dynamically allocate priorities to the DMA engines to maximize the efficiency in processing data.

Method for allocating priorities to plurality of DMA engines for processing data packets based on bus phase and transactions status

System for transferring data packets of different context utilizing single interface and concurrently processing data packets of different contexts

A method and apparatus for receiving packets from a bus. A packet is received at an interface to the bus. The packet is parsed, and a determination is made whether to retain the packet from the parsing of the packet. The packet is placed in a buffer with a header. The packet is moved from the buffer to another bus using information located within the header, wherein repeated parsing of the packet to move the packet to another bus is unnecessary.

Growing community of inventors

Fort Collins, CO, United States of America

David A Thomas