[alsa-devel] of_dma_request_slave_channel() failed ?

[Kuninori Morimoto]

Hi Geert

> > Before 6c92d5a2744e2761 patch, driver will forcibly ignore
> > non-SSI modules, and try to use PIO mode.
> > I'm not sure it is "kindly support" or "overkill support".
> >
> > After this patch, it needs DMA, otherwise, probe will be failed.
> > DT shouldn't have non-SSI modules if you want to use PIO mode.
> >
> >         + /* use PIO mode */
> >         - playback = <&ssi0 &src0 &dvc0>;
> >         + playback = <&ssi0>;
> >
> 
> OK, so falling back to PIO was really a "best effort" fallback, and the user
> should really enable DMA?

Yeah, I'm thinking this is better.
PIO fallback is of course "nice to have" if possible.
But, because of this new iommu patch, keeping this feature
needs "big complicated patch", and we can get "small effect" I think.
Thus, I think this is the time to remove this feature.
Can you agree ?

Best regards
---
Kuninori Morimoto