[PATCH] ASoC: dmaengine: Document support for TX only or RX only streams

[Andy Shevchenko]

On Mon, Oct 12, 2020 at 04:48:03PM +0100, Mark Brown wrote:
> On Mon, Oct 12, 2020 at 04:55:27PM +0300, Andy Shevchenko wrote:
> 
> > Currently those drivers need to do something like:
> 
> > 	if (of_property_is_present("dma-names"))
> > 		ret = try DMA mode;
> > 	else
> > 		ret = try PIO mode;
> 
> > but this seems to me a bit stricter than needed. What if DMA mode fails, shall
> > we fail the probe of the driver?
> 
> They can also just try registering DMA and fall back to PIO.

There is no possibility to do like this right now.

> > If ASoC supports optional DMA resources, above can be simplified to something
> > like:
> 
> > 	ret = try DMA mode;
> > 	if (ret != DMA mode ok)
> > 		ret = try PIO mode;
> 
> > which makes OF dependent parts gone along with relying on the properties rather
> > than real resource availability.
> 
> I don't understand the blocker to writing that code at the minute?

Return code in both cases DMA okay, DMA is not okay is 0.

-- 
With Best Regards,
Andy Shevchenko