Re: [PATCH 0/6] dmaengine: Add common dma_slave_config and split it into src and dst parts

[Frank Li]

On Mon, Mar 09, 2026 at 12:24:33PM +0100, Vinod Koul wrote:
> On 14-01-26, 12:12, Frank Li wrote:
> > Many DMA engine drivers store a dma_slave_config per channel. Propagate
> > this configuration into struct dma_chan to avoid duplicating the same
> > code in each driver.
> >
> > Much of dma_slave_config is identical for source and destination. Split
> > the configuration into src and dst groups and use a union to preserve
> > backward compatibility. This reduces the need for drivers to repeatedly
> > check the DMA transfer direction.
>
> The reason why we had both the src/dstn sides was intended method to
> allow upport ofr device to device dma. Some interest was shown for that
> at that time.
> I dont think we have such a user even now...

My means is the field name is identical, not value identical although most
case is the identical. but it is possible, especial FIFO space windows,

sound/soc/fsl/fsl_asrc_dma.c use DEV_TO_DEV, at least src and addr use
differece address.

Frank

>
>
> --
> ~Vinod