The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 19, 2004
Filed:
Oct. 23, 2000
James Murray, Mountain View, CA (US);
Jean-Didier Allegrucci, Sunnyvale, CA (US);
Xilinx Inc., San Jose, CA (US);
Abstract
A method for ensuring data coherency in buffered direct memory access (DMA) data transfers. The DMA controller realizes the last piece of data is being transferred to the write buffer. The DMA controller then sends a “Last Write Data” signal to the external memory access arbitration unit. The external memory access arbitration unit then allows completion of all pending memory operations. If a memory request occurs, a wait line is asserted such that memory operations (i.e., reading from, or writing to, the memory) are prevented for all sources other than the DMA channel associated with the “Last Write Data” signal. The external memory access arbitration unit also grants priority to the DMA channel associated with the “Last Write Data” signal. This effectively flushes the write buffer and completes the buffered DMA data transfer. The external memory access arbitration unit then deasserts any asserted wait lines and memory operations are no longer prevented.