linux-kernel - Re: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock

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Date:   Sun, 14 Feb 2021 23:26:36 +0530
From:   Sameer Pujar <spujar@...dia.com>
To:     Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
CC:     <broonie@...nel.org>, <robh@...nel.org>,
        <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>
Subject: Re: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock

Hi Morimoto-san,


On 2/12/2021 5:14 AM, Kuninori Morimoto wrote:
>> diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c
>> index bc0b62e..0754d70 100644
>> --- a/sound/soc/generic/simple-card-utils.c
>> +++ b/sound/soc/generic/simple-card-utils.c
>> @@ -173,16 +173,15 @@ int asoc_simple_parse_clk(struct device *dev,
>>         *  or device's module clock.
>>         */
>>        clk = devm_get_clk_from_child(dev, node, NULL);
>> -     if (!IS_ERR(clk)) {
>> -             simple_dai->sysclk = clk_get_rate(clk);
>> +     if (IS_ERR(clk))
>> +             clk = devm_get_clk_from_child(dev, dlc->of_node, NULL);
>>
>> +     if (!IS_ERR(clk)) {
>>                simple_dai->clk = clk;
>> -     } else if (!of_property_read_u32(node, "system-clock-frequency", &val)) {
>> +             simple_dai->sysclk = clk_get_rate(clk);
>> +     } else if (!of_property_read_u32(node, "system-clock-frequency",
>> +                                      &val)) {
>>                simple_dai->sysclk = val;
>> -     } else {
>> -             clk = devm_get_clk_from_child(dev, dlc->of_node, NULL);
>> -             if (!IS_ERR(clk))
>> -                     simple_dai->sysclk = clk_get_rate(clk);
>>        }
> The comment is indicating that that the clock parsing order,
> but this patch exchanges it.
> This comment also should be updated, I think.
>
>          /*
>           * Parse dai->sysclk come from "clocks = <&xxx>"
>           * (if system has common clock)
>           *  or "system-clock-frequency = <xxx>"
>           *  or device's module clock.
>           */

Yes, this can be rephrased now.

> asoc_simple_set_clk_rate() will be called if it has simple_dai->clk.
> CPU or Codec component clock rate will be exchanged by this patch, I think.
> I'm not sure the effect of this patch to existing boards.

If CPU or Codec node does not specifiy "mclk-fs" factor, 
asoc_simple_set_clk_rate() won't be called. So I don't think there would 
be any effect w.r.t clock rate. With this patch clocks would get 
enabled/disabled.

>
> And also, this patch has too many unneeded exchange,
> thus it was difficult to read for me.
> I think it can be simply like this ?
> It is understandable what it want to do.

I think the patch does exactly the same thing as what you are suggesting 
below. Am I missing anything?

>
> diff --git a/sound/soc/generic/simple-card-utils.c b/sound/soc/generic/simple-card-utils.c
> index 8c423afb9d2e..d441890de4dc 100644
> --- a/sound/soc/generic/simple-card-utils.c
> +++ b/sound/soc/generic/simple-card-utils.c
> @@ -168,16 +168,14 @@ int asoc_simple_parse_clk(struct device *dev,
>           *  or device's module clock.
>           */
>          clk = devm_get_clk_from_child(dev, node, NULL);
> +       if (IS_ERR(clk))
> +               clk = devm_get_clk_from_child(dev, dlc->of_node, NULL);
> +
>          if (!IS_ERR(clk)) {
>                  simple_dai->sysclk = clk_get_rate(clk);
> -
>                  simple_dai->clk = clk;
>          } else if (!of_property_read_u32(node, "system-clock-frequency", &val)) {
>                  simple_dai->sysclk = val;
> -       } else {
> -               clk = devm_get_clk_from_child(dev, dlc->of_node, NULL);
> -               if (!IS_ERR(clk))
> -                       simple_dai->sysclk = clk_get_rate(clk);
>          }
>
>          if (of_property_read_bool(node, "system-clock-direction-out"))