linux-kernel - Re: [alsa-devel] [PATCH] ASoC: soc-pcm: Use delay set in pointer function

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Date:   Tue, 31 Jul 2018 06:55:06 +0530
From:   "Agrawal, Akshu" <Akshu.Agrawal@....com>
To:     Mark Brown <broonie@...nel.org>, Takashi Iwai <tiwai@...e.de>
Cc:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@...a-project.org>, Alexander.Deucher@....com,
        djkurtz@...omium.org, Liam Girdwood <lgirdwood@...il.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [alsa-devel] [PATCH] ASoC: soc-pcm: Use delay set in pointer
 function



On 7/30/2018 9:20 PM, Mark Brown wrote:
> On Mon, Jul 30, 2018 at 05:32:21PM +0200, Takashi Iwai wrote:
> 
>> That said, if delay callback of CPU dai provides the additional delay,
>> the patch does correct thing.  OTOH, if CPU dai provides the base
>> delay instead, we need to clarify that it's rather a must; the delay
>> calculation in pointer callback becomes bogus in this scenario.
> 
> Part of the theory here is that every component might have a delay
> independently of the rest and we need to add them all together to figure
> out what the system as a whole will see.  Personally I'd rather just
> have everything use a callack consistently to avoid confusion.
> 

For consistency we can add a delay callback in snd_pcm_ops and modify
the drivers which directly assigning runtime->delay to use the callback.
Apart from the 2 drivers mentioned in commit message I also found
sound/usb to be doing the same and its delay getting lost.

Thanks,
Akshu