linux-kernel - Re: [PATCH] ASoC: q6apm-dai: schedule all the periods before we start streaming

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Message-ID: <35cf66a2-05ef-4e49-a146-ca96ab19fcf8@linaro.org>
Date: Mon, 3 Feb 2025 14:30:26 +0000
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Mark Brown <broonie@...nel.org>
Cc: lgirdwood@...il.com, perex@...ex.cz, tiwai@...e.com,
 krzysztof.kozlowski@...aro.org, pierre-louis.bossart@...ux.dev,
 linux-sound@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 linux-kernel@...r.kernel.org, dmitry.baryshkov@...aro.org
Subject: Re: [PATCH] ASoC: q6apm-dai: schedule all the periods before we start
 streaming



On 03/02/2025 14:17, Mark Brown wrote:
> On Mon, Feb 03, 2025 at 12:49:45PM +0000, srinivas.kandagatla@...aro.org wrote:
>> From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>>
>> With the existing code, we are only setting up one period at a time, in a
>> ping-pong buffer style. This tiggers lot of underruns in the dsp
>> leading to jitter noise during audio playback.
>>
>> Fix this by scheduling all the periods, this will ensure that the dsp
>> has enough buffer feed and ultimatley fixing the underruns and audio
>> distortion.
> 
> Should we be writing all periods or just the minimum number of periods
> that's configured?  Userspace might not have filled the whole buffer
> yet.
Just minimum number of periods or 1 period. We are queuing up all the 
periods to the DSP, so that we do not have to wait for period interrupt 
to queue the next one. This significantly reduces the latency in queuing 
the periods to dsp.

--srini