linux-kernel - Re: [PATCH v2 9/9] ASoC: simple-card: Handle additional devices

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Date:   Wed, 24 May 2023 00:08:50 +0000
From:   Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2 9/9] ASoC: simple-card: Handle additional devices


Hi

> An additional-devs subnode can be present in the simple-card top node.
> This subnode is used to declared some "virtual" additional devices.
> 
> Create related devices from this subnode and avoid this subnode presence
> to interfere with the already supported subnodes analysis.
> 
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> ---

simple-card is used in many boards, but is old.
Adding new feature on audio-graph-card/audio-graph-card2 instead of simple-card
is my ideal, but it is OK.

simple-card is possible to handle multiple DAI links by using
"dai-link" node on 1 Sound Card. see

	https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/sound/simple-card.yaml?h=v6.4-rc3#n294

Is this "additional-devs" available only one per 1 Card ?
If it is possible to use 1 additional-devs per 1 DAI link, I think this patch want to
care "dai-link".
Or adding temporally NOTE or FIXME message like /* NOTE: it doesn't support dai-link so far */
is good idea.

>  static int asoc_simple_probe(struct platform_device *pdev)
>  {
>  	struct asoc_simple_priv *priv;
> @@ -688,6 +731,11 @@ static int asoc_simple_probe(struct platform_device *pdev)
>  		return ret;
>  
>  	if (np && of_device_is_available(np)) {
> +		ret = simple_populate_aux(priv);
> +		if (ret < 0) {
> +			dev_err_probe(dev, ret, "populate aux error\n");
> +			goto err;
> +		}
>  
>  		ret = simple_parse_of(priv, li);
>  		if (ret < 0) {
> -- 
> 2.40.1
> 

Calling simple_populate_aux() before calling simple_parse_of() is possible,
but looks strange for me.
see below

> diff --git a/sound/soc/generic/simple-card.c b/sound/soc/generic/simple-card.c
> index 5a5e4ecd0f61..4992ab433d6a 100644
> --- a/sound/soc/generic/simple-card.c
> +++ b/sound/soc/generic/simple-card.c
(snip)
> @@ -359,6 +360,8 @@ static int __simple_for_each_link(struct asoc_simple_priv *priv,
>  		is_top = 1;
>  	}
>  
> +	add_devs = of_get_child_by_name(top, PREFIX "additional-devs");

I think better position to call simple_populate_aux() is here.
But __simple_for_each_link() will be called multiple times for CPU and for Codec.
So maybe you want to calling it under CPU turn.

	 /* NOTE: it doesn't support dai-link so far */
	add_devs = of_get_child_by_name(top, PREFIX "additional-devs");
	if (add_devs && li->cpu) {
		ret = simple_populate_aux(priv);
		...
	}

Thank you for your help !!

Best regards
---
Kuninori Morimoto