[alsa-devel] [RFC 4/7] ASoC: Add dmaengine PCM helper functions

Kuninori Morimoto kuninori.morimoto.gx at renesas.com
Wed Mar 7 01:38:30 CET 2012

Hi Lars, Mark

> > > It would also be good to update FSI to use this library as it's also
> > > using dmaengine (the patch having been merged just before this one it
> > > got missed in the updates I expect).
> > I've had a look at the FSI dmaengine driver and it is not straight forward
> > to convert. For one it does not use cyclic dma transfers so it is more
> > something for Russel's patch and on the other hand the FSI PCM driver
> > introduces another layer of indirection which is used to be able to switch
> > between PIO and DMA. But as a result the functions the dmaengine PCM
> > framework provides don't really fit anymore.
> OK, fair enough.

FSI can switch PIO/DMA, but it will be decided on _probe() timing, not runtime switch.
PIO/DMA is depend on SuperH CPU/platform supporting status.

And yes, it doesn't use cyclic dma transfer since I don't know how to use it :)

I forgot detail, but I used sound/soc/sh/siu_pcm.c and sound/soc/txx9/txx9aclc.c
as sample code when I created FSI DMAEngine support.

If ASoC layer supports dmaengine helper functions, I can switch to it by my incremental patch.

Best regards
Kuninori Morimoto

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