linux-kernel - Re: [v7 2/4] ASoC: mediatek: mt8192: refactor for I2S3 DAI link of speaker

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Date:   Thu, 31 Mar 2022 00:20:09 +0800
From:   Jiaxin Yu <jiaxin.yu@...iatek.com>
To:     "Nícolas F. R. A. Prado" <nfraprado@...labora.com>
CC:     <broonie@...nel.org>, <robh+dt@...nel.org>, <tzungbi@...gle.com>,
        <angelogioacchino.delregno@...labora.com>, <aaronyu@...gle.com>,
        <matthias.bgg@...il.com>, <trevor.wu@...iatek.com>,
        <linmq006@...il.com>, <alsa-devel@...a-project.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@...iatek.com>,
        Tzung-Bi Shih <tzungbi@...nel.org>
Subject: Re: [v7 2/4] ASoC: mediatek: mt8192: refactor for I2S3 DAI link of
 speaker

On Wed, 2022-03-30 at 11:20 -0400, Nícolas F. R. A. Prado wrote:

> > > >  static int mt8192_mt6359_dev_probe(struct platform_device
> > > > *pdev)
> > > >  {
> > > >  	struct snd_soc_card *card;
> > > > -	struct device_node *platform_node, *hdmi_codec;
> > > > +	struct device_node *platform_node, *hdmi_codec,
> > > > *speaker_codec;
> > > >  	int ret, i;
> > > >  	struct snd_soc_dai_link *dai_link;
> > > >  	struct mt8192_mt6359_priv *priv;
> > > >  
> > > > -	platform_node = of_parse_phandle(pdev->dev.of_node,
> > > > -					 "mediatek,platform",
> > > > 0);
> > > > -	if (!platform_node) {
> > > > -		dev_err(&pdev->dev, "Property 'platform'
> > > > missing or
> > > > invalid\n");
> > > > +	card = (struct snd_soc_card
> > > > *)of_device_get_match_data(&pdev-
> > > > > dev);
> > > > 
> > > > +	if (!card)
> > > >  		return -EINVAL;
> > > > +	card->dev = &pdev->dev;
> > > > +
> > > > +	platform_node = of_parse_phandle(pdev->dev.of_node,
> > > > "mediatek,platform", 0);
> > > > +	if (!platform_node) {
> > > > +		ret = -EINVAL;
> > > > +		dev_err_probe(&pdev->dev, ret, "Property
> > > > 'platform'
> > > > missing or invalid\n");
> > > > +		goto err_platform_node;
> > > >  	}
> > > >  
> > > > -	card = (struct snd_soc_card
> > > > *)of_device_get_match_data(&pdev-
> > > > > dev);
> > > > 
> > > > -	if (!card) {
> > > > +	hdmi_codec = of_parse_phandle(pdev->dev.of_node,
> > > > "mediatek,hdmi-codec", 0);
> > > > +	if (!hdmi_codec) {
> > > >  		ret = -EINVAL;
> > > > -		goto put_platform_node;
> > > > +		dev_err_probe(&pdev->dev, ret, "Property 'hdmi-
> > > > codec'
> > > > missing or invalid\n");
> > > > +		goto err_hdmi_codec;
> > > 
> > > You're making hdmi-codec a required property, since now the
> > > driver
> > > fails to
> > > probe without it. Is it really required though? The driver code
> > > still
> > > checks for
> > > the presence of hdmi_codec before using it, so shouldn't it be
> > > fine
> > > to let it be
> > > optional?
> > > 
> > > If it is really required now though, then I guess at least the
> > > dt-
> > > binding should
> > > be updated accordingly. (Although I think this would technically
> > > break the ABI?)
> > > 
> > > Thanks,
> > > Nícolas
> > 
> > Hi Nícolas,
> > 
> > Thanks for your comment. Indeed I made hdmi-codec a required
> > property,
> > because it is a must in this machine driver. I prefer to report
> > errors
> > during the registration rather than during the use.
> 
> But what do you mean that it is required in this machine driver? The
> code checks
> for presence of hdmi_codec and ignores it if it's not set, so it does
> really
> seem optional to me. Also, I have tested this driver on mt8192-
> asurada-spherion
> without hdmi-codec set in the DT and the speaker and headphone sound
> works just
> fine.
> 
> Besides, there might be machines using this driver that don't support
> HDMI, and
> requiring an hdmi-codec in the DT for them would not make any sense.
> So keeping
> hdmi-codec as optional seems like the most sensible solution to me,
> really.
> 
> Thanks,
> Nícolas

Yes, I agree with you. In the past, if there was a new board without
HDMI audio, we would choose to add a new machine driver and a new dt-
bindings. But now, in order to simplify the code, we tend to share one
machine driver for boards that use similar codecs. And we are doing
this now.

Thanks,
Jiaxin.Yu