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Most CF Cards Fail DMA Transfers

Posted by kdawson on from the it's-all-in-the-controller dept.

Anomalyst writes "In his quest to create an open source video camera, Andrey Filippov of elphel.com has determined that most Compact Flash devices, although claiming to be DMA capable, do not perform Direct Memory Access transfers correctly. This means successful movement of data to and from the device takes much more time with DMA disabled." The culprit appears to be the controller chip packaged with most of the CF cards Filippov tried. We last visited Elphel and their work on open source digital cameras in 2002. Filippov gave a Tech Talk at Google last year.

3 of 140 comments (clear)

  1. Slower with DMA disabled? by foobrain · · Score: 0, Troll

    "This means successful movement of data to and from the device takes much more time with DMA disabled."

    Oh, really? If so, the devices works as they should.

  2. Re:Good work by Anonymous Coward · · Score: -1, Troll

    Hello,
    OP here. You are deluded. Try plugging a Canon S3 into a computer that never had any Canon hardware on it. Perhaps your ass is so slack from pulling such stupidities out of it so often.

    1) You need the correct USB cable because the camera tries to act as a host (so it can drive a printer). Thing is, all these cables look exactly the same.
    2) You need to install Canon's sheisse to access the camera.

    Try it. I did. Did you? Or is your turd cutter doing all the typing again?

  3. I think I hear Violins by billcopc · · Score: -1, Troll

    Cheap Chinese mass-produced gadgets fail to perform as advertised, C-list Slashdot editor posts trollish story, film at 11!

    --
    -Billco, Fnarg.com