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    SubjectRe: [PATCHv4] DMAEngine: Define interleaved transfer request api
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    On Mon, 2011-10-10 at 15:23 +0530, Jassi Brar wrote:
    > On 10 October 2011 14:48, Vinod Koul <vinod.koul@intel.com> wrote:
    > > On Mon, 2011-10-10 at 14:46 +0530, Jassi Brar wrote:
    > >> On 10 October 2011 12:23, Vinod Koul <vinod.koul@intel.com> wrote:
    > >> >
    > >> > +struct dmaxfer_memcpy_template {
    > >> > + dma_addr_t src_start;
    > >> > + dma_addr_t dst_start;
    > >> > + bool src_inc;
    > >> > + bool dst_inc;
    > >> > + bool src_sgl;
    > >> > + bool dst_sgl;
    > >> > + size_t numf;
    > >> > + size_t frame_size;
    > >> > + struct data_chunk sgl[0];
    > >> > +};
    > >> > +
    > >> > +struct dmaxfer_slave_template {
    > >> > + dma_addr_t mem;
    > >> > + bool mem_inc;
    > >> > + size_t numf;
    > >> > + size_t frame_size;
    > >> > + struct data_chunk sgl[0];
    > >> > +};
    > >> >
    > >> (1) Please tell how is dmaxfer_slave_template supposed to work on
    > >> bi-directional channels?
    > >> Keeping in mind, dma_slave_config.direction is marked to go away
    > >> in future.
    > > I didn't use dma_slave_config.direction. There is direction field in
    > > corresponding prepare function.
    > >
    > ok but why not reduce 1 argument from api and embed that as
    > the transfer's property in dmaxfer_slave_template, as I did ?
    I am not religious about it, doesn't matter either way :)
    >
    > >>
    > >> (2)
    > >> * slave_template.mem <=> memcpy_template.src_start
    > >> * slave_template.mem_inc <=> memcpy_template.src_inc
    > >>
    > >> So essentially
    > >> memcpy_template := slave_template + src/dst_sgl + dst_start + dst_inc
    > >>
    > >> Even after this separation, there is nothing slave specific in
    > >> dmaxfer_slave_template. The slave client still needs DMA_SLAVE_CONFIG
    > >> to specify slave parameters of the transfer.
    > >> You only save a few bytes in a _copy_ of memcpy_template.
    > > Yes DMA_SLAVE_CONFIG is always required, this attempt was not aimed to
    > > remove that, but I would be interested in it :)
    > >
    > Sorry then I don't see this "ambiguity"(if there really is any) removal worth
    > adding an extra prepare when we already have 10 of them.
    For slave we have only two, and we can easily merge cyclic by adding a
    flag or something, I planning to do that for next merge cycle.

    IMO having one more for interleaved-slave should be okay.

    But I am fine if we find a common ground and merge the two where dmac
    can cleanly identify direction and mode it is operating.

    --
    ~Vinod



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