Integrated Device Technology, Inc.

Jiann Liao

Jeffrey Lukanc

Cesar A Talledo

Ming Tang

Agha B Hussain

In PCI-Express and alike communications systems, number of lanes used per channel or port can vary as a result of negotiated lane aggregation during network bring-up. Disclosed are systems and methods for efficiently realigning packet data and stripping out control bytes in a by-eight port configuration as the packet data ingresses from the physical layer (PL), past the data link layer (DL) and into the transaction layer (TL). It is shown that data routing can be reduced to just two, mux-selectable permutations based on whether the STP (start of packet) character arrives in an even numbered double-word side (DW) or an odd-numbered double-word side (DW) of a physical layer register.

Efficient strip-down and re-alignment of ingressing physical layer/data layer packets in an aggregated PCI-express port having eight lanes

A computer system is provided that includes a direct memory access (DMA) controller, a memory control device and a slave device, all coupled to a system bus. The DMA controller is configured to implement fly-by read and fly-by write operations between the memory control device and the slave device. The memory control device and the slave device each include read and write aligners. During a fly-by read, data is read from slave device and aligned to the system bus using a peripheral read aligner. The memory control device re-aligns the data received on the system bus using a write aligner and writes the data to a main memory. During a fly-by write, data is read from the main memory and aligned to the system bus using a read aligner in memory control device. A write aligner in the slave device then re-aligns the data received on the system bus.

Transaction aligner microarchitecture

A method and apparatus for reducing latency due to set up time between DMA transfers are described. The method comprises initiating arbitration of DMA channel requests prior to completion of a current DMA transfer; and initiating set up for a next DMA transfer prior to completion of the current DMA transfer according to the arbitration. One implementation of the apparatus includes one or more DMA channel interfaces providing a series of DMA channel requests such that a DMA channel request for a next DMA transfer is provided before a current DMA transfer is completed; and a DMA controller that initiates arbitration of DMA channel requests after they are provided by the one or more DMA channel interfaces and before the current DMA transfer is completed, and initiates set up for the next DMA transfer prior to completion of the current DMA transfer according to the arbitration.

Method and apparatus for reducing latency due to set up time between DMA transfers

A system is provided that includes a bus master, a bus slave and a fly-by slave interface, all coupled to a peripheral bus. A peripheral device is coupled to the fly-by slave interface. The bus master is configured to control fly-by transfer of data between the bus slave and the peripheral device without buffering the data. The fly-by slave interface is configured to isolate the peripheral device from the peripheral bus during fly-by transfer of data between the bus slave and the peripheral device. In addiction, the bus slave is configured to provide a set of control signals on the peripheral bus, wherein the control signals regulate the flow of data on the peripheral bus during fly-by transfer of data between the bus slave and the peripheral device. Fly-by transfers can be fully synchronous, and burst operation at the rate of one data value per clock cycle is supported.

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Campbell, CA, United States of America

Jiann Liao