Date: Wed, 27 May 2015 19:55:55 +0530 From: Pratik Singhal <ps06756@gmail.com> To: FreeBSD Questions <freebsd-questions@freebsd.org> Subject: How do we use the bus_dma interface ? Message-ID: <CAGf2gkPyiq2rZ-5dGQ0zMYRLf67%2BbmXwJs32ZQ_UvckG%2BdwB6Q@mail.gmail.com>
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Hello, I have to program the Cubieboard's DMA controller. So far, after the initialization of the driver, to perform DMA transfer I was trying to pass the actual physical address to the DMA controller which I came to know that, is not the correct way to program the DMA controller. Instead, I should try using the bus_dma(9) interface. I have read the relevant parts of the DMA from the book FreeBSD Device Driver, but I am unable to understand the bus_dma interface. (How to use it ? ) . Can someone please give a overview of the whole process (tags and maps) so that I can at least get started on the programming part. for ex, How should I use the interface to start the DMA transfer ? Regards, Pratik Singhal
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