linux-kernel - Re: [PATCH v3 10/13] ASoC: tegra: Add audio graph based card driver

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Date:   Fri, 2 Oct 2020 14:38:24 +0530
From:   Sameer Pujar <spujar@...dia.com>
To:     Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
CC:     <broonie@...nel.org>, <lgirdwood@...il.com>, <robh+dt@...nel.org>,
        <pierre-louis.bossart@...ux.intel.com>, <perex@...ex.cz>,
        <tiwai@...e.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <alsa-devel@...a-project.org>,
        <devicetree@...r.kernel.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 v3 10/13] ASoC: tegra: Add audio graph based card driver


>> Add Tegra audio machine driver which is based on generic audio graph card
>> driver. It re-uses most of the common stuff from audio graph driver and
>> uses the same DT binding. Required Tegra specific customizations are done
>> in the driver.
> (snip)
>> +static const struct snd_soc_ops tegra_audio_graph_ops = {
>> +     .startup        = asoc_simple_startup,
>> +     .shutdown       = asoc_simple_shutdown,
>> +     .hw_params      = tegra_audio_graph_hw_params,
>> +};
> This is just an idea,
> but can we use hooks here somehow ?
>
>          .ops_hook_pre
>          .ops_hook_func
>          .ops_hook_post
>
>          if (priv->ops_hook_pre->func)
>                  priv->ops_hook_pre->func_pre(...);
>
>          if (priv->ops_hook_func->func)
>                  priv->ops_hook_func->func(...); /* driver's function */
>          else
>                  graph_func(...);        /* audio-graph function */
>
>          if (priv->ops_hook_post->func)
>                  priv->ops_hook_post->func(...);

Right now I just required to populate some flags or structures and do 
not have any specific pre()/post() functions to be called. Can this be 
reserved for later?

>
>
>> +static int tegra_audio_graph_probe(struct platform_device *pdev)
>> +{
>> +     struct asoc_simple_priv *priv;
>> +     struct device *dev = &pdev->dev;
>> +     struct snd_soc_card *card;
>> +     struct link_info li;
>> +     int err;
>> +
>> +     /* Allocate the private data and the DAI link array */
>> +     priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> +     if (!priv)
>> +             return -ENOMEM;
>> +
>> +     priv->data = (struct tegra_audio_graph_data *)
>> +             devm_kzalloc(dev, sizeof(*priv->data), GFP_KERNEL);
>> +     if (!priv->data)
>> +             return -ENOMEM;
>> +
>> +     card = simple_priv_to_card(priv);
>> +
>> +     card->owner = THIS_MODULE;
>> +     card->dev = dev;
>> +     card->component_chaining = true;
>> +     card->probe = tegra_audio_graph_card_probe;
>> +
>> +     priv->ops = &tegra_audio_graph_ops;
>> +     priv->force_dpcm = 1;
>> +
>> +     memset(&li, 0, sizeof(li));
>> +     graph_get_dais_count(priv, &li);
>> +     if (!li.link || !li.dais)
>> +             return -EINVAL;
>> +
>> +     err = asoc_simple_init_priv(priv, &li);
>> +     if (err < 0)
>> +             return err;
>> +
>> +     err = graph_parse_of(priv);
>> +     if (err < 0) {
>> +             if (err != -EPROBE_DEFER)
>> +                     dev_err(dev, "Parse error %d\n", err);
>> +             goto cleanup;
>> +     }
>> +
>> +     snd_soc_card_set_drvdata(card, priv);
>> +
>> +     asoc_simple_debug_info(priv);
>> +
>> +     err = devm_snd_soc_register_card(dev, card);
>> +     if (err < 0)
>> +             goto cleanup;
>> +
>> +     return 0;
>> +
>> +cleanup:
>> +     asoc_simple_clean_reference(card);
>> +
>> +     return err;
>> +}

> These are almost same as graph_probe().
> Maybe we can separate graph_probe() and export function ?

Yes possible, I can move more stuff into graph_parse_of() which is 
already an exported function in the current series. This can be utilized 
by both generic audio graph and Tegra audio graph.

Something like below,

static int tegra_audio_graph_probe(struct platform_device *pdev)
{
         struct tegra_audio_priv *priv;
         struct device *dev = &pdev->dev;
         struct snd_soc_card *card;

         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
         if (!priv)
                 return -ENOMEM;

         card = simple_priv_to_card(&priv->simple);

         card->owner = THIS_MODULE;
         card->dev = dev;
         card->probe = tegra_audio_graph_card_probe;

         /* graph_parse_of() depends on below */
         card->component_chaining = 1;
         priv->simple.ops = &tegra_audio_graph_ops;
         priv->simple.force_dpcm = 1;

         return graph_parse_of(&priv->simple);
}

Does this sound fine?