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    SubjectRe: Question about DMA
    On 01/27/2008 09:51 PM, Francis Moreau wrote:
    > Hello,
    >
    > I have 2 questions regarding set_dma_addr(unsigned int channel,
    > unsigned int addr) helper.
    >
    > 1/ Why does the function take only one address ? I would expect it
    > to take both a source and a destination address for the dma controller
    > to transfer data.

    since your device is responsible for sending data from/to local memory. ISA dma
    controller has only 2 registers -- 16-bit address to put incoming data to (get
    outcoming from) + 8-bit nonincrementing page and 16-bit counter.

    > 2/ The type of address parameter is an unsigned int. Why isn't it a dma_addr_t
    > type ?

    since isa dma controller can address up to 2^24 (16-bit address + 8-bit page)
    bytes of memory, i.e. 16M.

    Are you sure, you want use this API?



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