linux-kernel - Re: [PATCH v4 12/23] ASoC: simple-card: Support DPCM DAI link with multiple Codecs

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Message-ID: <87ftadyrec.wl-kuninori.morimoto.gx@renesas.com>
Date:   30 Jun 2020 15:55:40 +0900
From:   Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:     Sameer Pujar <spujar@...dia.com>
Cc:     <broonie@...nel.org>, <perex@...ex.cz>, <tiwai@...e.com>,
        <robh+dt@...nel.org>, <lgirdwood@...il.com>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <digetx@...il.com>, <alsa-devel@...a-project.org>,
        <linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <sharadg@...dia.com>, <mkumard@...dia.com>,
        <viswanathl@...dia.com>, <rlokhande@...dia.com>,
        <dramesh@...dia.com>, <atalambedu@...dia.com>,
        <nwartikar@...dia.com>, <swarren@...dia.com>,
        <nicoleotsuka@...il.com>
Subject: Re: [PATCH v4 12/23] ASoC: simple-card: Support DPCM DAI link with multiple Codecs


Hi Sameer

Thank you for explaining detail at off-list mail.

Your issue happen on (C) case, and you are tring to solve it.
It is easy to understand if it was indicated at log area.
I have imagined other system from "multiple CPU/Codec support".

	(A)    (B)
	FE <-> BE

	(C)    (D)
	BE <-> BE

> > I'm not sure, this is just my guess.
> > I'm happy if we can support it more easily :)
> Right now I am trying re-use simple-card driver as much as possible
> and still make it work for flexible sound cards. I will be happy to
> discuss and improve the patch wherever necessary. Please help me
> understand which part you think looks to be hacky.

> > But, if it was difficult to keep compatibility on simple-card,
> > we/you need to have new one.
> Patch 17/23 and 18/23 introduce new compatible
> 'simple-cc-audio-card'. Idea was to use component chaining which
> allows connection of FE<->BE and multiple BE<->BE components along the
> DAPM path (patch 16/23). Do you think it would be fine?

This seems very complex system for current simple-card.
"concept" of simple-card is simple (but "code" is not so simple...)
Because of it, it doesn't assume flexible connection.

Maybe your patch works for you, but might breaks other systems.
Or, makes code or DT settings more complex/ununderstandable.
Not sure, but my guess.

Using cpu@0 node for BE is the 1st confusable point for me.
Using fe/be instead of cpu/codec is easy to understand.

Thank you for your help !!

Best regards
---
Kuninori Morimoto