Re: [PATCHv4] DMAEngine: Define interleaved transfer request api

From: Vinod Koul
Date: Mon Oct 10 2011 - 05:26:04 EST


On Mon, 2011-10-10 at 14:46 +0530, Jassi Brar wrote:
> On 10 October 2011 12:23, Vinod Koul <vinod.koul@xxxxxxxxx> 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.

>
> (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 :)

--
~Vinod

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