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    SubjectRe: [PATCHv2] DMAEngine: Let dmac drivers to set chan_id
    On 28 July 2011 02:07, Russell King <> wrote:
    >> On a serious note, my proposal, and the reply, shows the possibility
    >> of having :-
    >> a) Client drivers that are truly platform agnostic -- no platform_data
    >> poking for
    >>       channel selection
    > I really doubt that's even possible.  Take this setup:

    I don't want to suggest anything wrong just because I didn't understand
    your h/w.
    I hope you will be kind enough to help me better understand your setup,
    so that I have a fair chance to present my proposal.

    A simple 'yes' or a 'no'(with clarification) is all I ask.

    > MMCI ---> DMAC
    > where the DMAC has 32 request signals, and 8 channels.
    The DMAC is similar to PL330.
    Only max 8 request-signals can be active at any time.
    Is my understanding right ?

    > The MMCI is connected to two of them.
    I don't know anything about MMCI.
    So I assume it is just another third party MMC controller.
    It simply needs 2 dma channels(for RX, TX each) - be it from a DMAC
    that has a programmable RequestSignal->Peripheral map or a fixed map.
    Is my understanding right ?

    > The DMAC can supply any of its physical channels for MMCI.
    The RequestSignal->Peripheral map is decided during board design
    and can not be changed later.
    Is my understanding right ?

    > Board 1 has the MMCI connected to request signals #1 and #3.
    > Board 2 has the MMCI connected to request signals #8 and #22.
    MMCI_RX -> #1
    MMCI_TX -> #3

    MMCI_RX -> #8
    MMCI_TX -> #22

    > Board 3 has the MMCI connected through an external FPGA mux, which can route the
    > MMCI requests to DMA request signals #1, #2 or #3.
    MMCI_RX -> #{1,2,3}
    MMCI_TX -> #{1,2,3}
    And you can't change the route(mapping) after the dmac driver has been loaded.
    Is my understanding right ?
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