linux-kernel - Re: [alsa-devel] [PATCH v2] ASoC: da7219: read fmw property to get mclk for non-dts systems

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Date:   Tue, 1 May 2018 20:01:24 +0530
From:   "Agrawal, Akshu" <Akshu.Agrawal@....com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     "moderated list:SOUND" <alsa-devel@...a-project.org>,
        Support Opensource <support.opensource@...semi.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        open list <linux-kernel@...r.kernel.org>,
        Takashi Iwai <tiwai@...e.com>, djkurtz@...omium.org,
        Mark Brown <broonie@...nel.org>, Alexander.Deucher@....com,
        Adam.Thomson.Opensource@...semi.com
Subject: Re: [alsa-devel] [PATCH v2] ASoC: da7219: read fmw property to get
 mclk for non-dts systems



On 4/30/2018 9:54 PM, Pierre-Louis Bossart wrote:
> On 4/30/18 4:23 AM, Akshu Agrawal wrote:
>> Non-dts based systems can use ACPI DSDT to pass on the mclk
>> to da7219.
>> This enables da7219 mclk to be linked to system clock.
>> Enable/Disable of the mclk is already handled in the codec so
>> platform drivers don't have to explicitly do handling of mclk.
>>
>> Signed-off-by: Akshu Agrawal <akshu.agrawal@....com>
>> ---
>> v2: Fixed kbuild error
>>   include/sound/da7219.h    | 2 ++
>>   sound/soc/codecs/da7219.c | 7 ++++++-
>>   2 files changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/sound/da7219.h b/include/sound/da7219.h
>> index 1bfcb16..df7ddf4 100644
>> --- a/include/sound/da7219.h
>> +++ b/include/sound/da7219.h
>> @@ -38,6 +38,8 @@ struct da7219_pdata {
>>       const char *dai_clks_name;
>> +    const char *mclk_name;
>> +
>>       /* Mic */
>>       enum da7219_micbias_voltage micbias_lvl;
>>       enum da7219_mic_amp_in_sel mic_amp_in_sel;
>> diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
>> index 980a6a8..aed68a4 100644
>> --- a/sound/soc/codecs/da7219.c
>> +++ b/sound/soc/codecs/da7219.c
>> @@ -1624,6 +1624,8 @@ static struct da7219_pdata 
>> *da7219_fw_to_pdata(struct snd_soc_component *compone
>>           dev_warn(dev, "Using default clk name: %s\n",
>>                pdata->dai_clks_name);
>> +    device_property_read_string(dev, "dlg,mclk-name", 
>> &pdata->mclk_name);
>> +
>>       if (device_property_read_u32(dev, "dlg,micbias-lvl", &of_val32) 
>> >= 0)
>>           pdata->micbias_lvl = da7219_fw_micbias_lvl(dev, of_val32);
>>       else
>> @@ -1905,7 +1907,10 @@ static int da7219_probe(struct 
>> snd_soc_component *component)
>>       da7219_handle_pdata(component);
>>       /* Check if MCLK provided */
>> -    da7219->mclk = devm_clk_get(component->dev, "mclk");
>> +    if (da7219->pdata->mclk_name)
>> +        da7219->mclk = clk_get(NULL, da7219->pdata->mclk_name);
>> +    if (!da7219->mclk)
>> +        da7219->mclk = devm_clk_get(component->dev, "mclk");
> 
> this looks weird, why are you using different clk functions depending on 
> the existence of a _DSD property? Why not just change the name and keep 
> the same flow, e.g something like
> 
> if(!da7219->pdata->mclk_name)
>      da7219->pdata->mclk_name = "mclk";
> da7219->mclk = devm_clk_get(component->dev, da7219->pdata->mclk_name);
> 
> 

We can't use devm_clk_get as the value of dev argument has to be NULL, 
which can not be used with devm_clk_get.
System clock which are linked to mclk are registered by a separate ACPI 
device. And this exposing of DSD property is for all those platforms 
which are non-dts based.

>>       if (IS_ERR(da7219->mclk)) {
>>           if (PTR_ERR(da7219->mclk) != -ENOENT) {
>>               ret = PTR_ERR(da7219->mclk);
>>
>