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

Mark Brown broonie at kernel.org
Mon Oct 12 17:48:03 CEST 2020


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.

> 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?
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