[alsa-devel] [PATCH] ASoC: dmaengine_pcm: Consider DMA cache caused delay in pointer callback

[Mark Brown]

On Mon, Feb 10, 2020 at 04:28:44PM +0200, Peter Ujfalusi wrote:
> On 10/02/2020 16.21, Takashi Iwai wrote:

> >>  	delay += codec_delay;
> >>  
> >> -	runtime->delay = delay;
> >> +	runtime->delay += delay;

> > Is it correct?
> > delay already takes runtime->delay as its basis, so it'll result in a
> > double.

> The delay here is coming from the DAI and the codec.
> The runtime->delay hold the PCM (DMA) caused delay.

I think Takashi's point here (and a query I have) is that we end up with

	delay = runtime->delay;
	delay += stuff;
	runtime->delay += delay;

which is equivalent to

	runtime->delay = (runtime->delay * 2) + stuff;

and that's a bit surprising.
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