linux-kernel - Re: [PATCH v2 7/9] ASoC: codecs: Add support for the generic IIO auxiliary devices

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Message-ID: <20230607152308.02b404e1@bootlin.com>
Date:   Wed, 7 Jun 2023 15:23:08 +0200
From:   Herve Codina <herve.codina@...tlin.com>
To:     andy.shevchenko@...il.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>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.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 7/9] ASoC: codecs: Add support for the generic IIO
 auxiliary devices

Hi Andy,

On Tue, 6 Jun 2023 15:54:04 +0200
Herve Codina <herve.codina@...tlin.com> wrote:

...
> >   
> > > +	platform_set_drvdata(pdev, iio_aux);    
> > 
> > Which callback is using this driver data?  
> 
> None -> I will remove platform_set_drvdata().
> 

My previous answer was not correct.
The platform_set_drvdata() call is needed.

In fact, the driver uses snd_soc_component_get_drvdata() 
  https://elixir.bootlin.com/linux/v6.4-rc5/source/include/sound/soc-component.h#L425
and this snd_soc_component_get_drvdata() get the driver data set by the
platform_set_drvdata() call.

I cannot use snd_soc_component_set_drvdata() to set the driver data because
I haven't got the struct snd_soc_component instance when I need to set the
driver data.

So, I will not remove the platform_set_drvdata() call.

The sequence is:
  --- 8< ---
  static int audio_iio_aux_probe(struct platform_device *pdev)
  {
	struct audio_iio_aux *iio_aux;

	iio_aux = devm_kzalloc(&pdev->dev, sizeof(*iio_aux), GFP_KERNEL);
	if (!iio_aux)
		return -ENOMEM;

	...

	platform_set_drvdata(pdev, iio_aux);

	return devm_snd_soc_register_component(iio_aux->dev,
					       &audio_iio_aux_component_driver,
					       NULL, 0);
  }
  --- 8< ---

The struct snd_soc_component instance will be create during the 
devm_snd_soc_register_component() call.

Regards,
Hervé

-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com