DMA transfer help

[dhanisch]

All,

I am attempting to DMA transfer a block of data from a FIFO in a Virtex 4.  I'm attempting to write a device driver that performs this transfer from a custom peripheral to local memory.  Any relative examples available that specifically use the DMA controller that is built-in to the custom peripheral.  I thought the xilinx_emac driver would be a good example, but I'm unsure.  Any help would be appreciated.

Thanks,

David

[Anonymous]

Hi David - Sounds like you may be using older tools. The more "modern" way of doing DMA is by using the SDMA PIM built into the MPMC, which is connected to a peripheral with a locallink interface. Please see the following app notes - the first talks about building a custom localllink peripheral, the second talks about integrating a locallink peripheral into Linux. http://www.xilinx.com/support/documentation/application_notes/xapp1126.pdf http://www.xilinx.com/support/documentation/application_notes/xapp1129.pdf Now if you already have a older hardware system that you can't change, that's a different story.. Please elaborate on your hardware configuration. Terry

[dhanisch]

I'm using EDK 10.1 but am using an older EDK project making use of the OPB and PLB(version 3.4?) bus.  I have a custom peripheral that writes data to a FIFO.  When this FIFO fills, I want to DMA all that data from the peripheral to local memory without use of the CPU to prevent overtaxing the CPU. Please let me know if you need further elaboration as to my hardware setup.

Thanks,

David

[Anonymous]

Does your custom peripheral have a PLB master interface? What are you using for the memory controller?

[dhanisch]

The custom peripheral has a master OPB interface and the overall project has an OPB-to-PLB bridge.  The memory controller being used is the plb_ddr (version 2.00.a).  I appear to have it working by simply mapping the peripheral's memory and being careful about writing to the particular registers necessary for the DMA transfer.

Thanks,

David