Most CF Cards Fail DMA Transfers

Posted by kdawson on Saturday July 12, 2008 @07:28AM 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.

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Re:Lexar and Sandisk should be good by LanceUppercut · 2008-07-12 07:49 · Score: 5, Interesting

How do you know that it indeed works in a full-fledged UDMA mode and not in some half-assed workaround mode, used specifically because of the problems in question existing in the cards' controllers. Did you reverse engineer the camera's firmware?