Re: [PATCH] ASoC: pcm512x: Add support for data formats RJ and LJ

[Kirill Marinushkin]

Hello Peter,

On 11/12/2020 08:41 AM, Peter Ujfalusi wrote:
> Hi Kirill,
> 
> On 11/11/2020 9.54, Kirill Marinushkin wrote:
>> Hello Peter,
>>
>> than you for your review!
>>
>>> The bus format and
>>>
>>>>  	switch (pcm512x->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
>>>
>>>>  	case SND_SOC_DAIFMT_CBS_CFS:
>>>>  		ret = regmap_update_bits(pcm512x->regmap,
>>>
>>> the clock generation role should be set in pcm512x_set_fmt(), in that
>>> way you can deny specific setups earlier.
>>
>> I think we could move both checks for`SND_SOC_DAIFMT_FORMAT_MASK` and
>> `SND_SOC_DAIFMT_MASTER_MASK` into `pcm512x_set_fmt()`. But it would be a
>> different scope, and I didn't intend to do that level of refactoring.
> 
> Right, I was just saying what would make sense.
> 
>> Looking at other codecs in kernel, I would say, that doing those checks in
>> `pcm512x_hw_params()`, as they are done currently, is an equally valid approach.
> 
> The exception proves the rule
> 
>> As technically keeping checs where they are now doesn't break anything
> 
> They are just in a wrong place.
> 
>> and is
>> aligned with ASoC codecs design, I suggest to keep the checks where they are.
> 
> The set_fmt callback is there to set the bus format, it has nothing to
> do (in most cases) with the sample format (hw_params). Bus coding, clock
> source has nothing to do with hw_params.
> 
> When you bind a link you will use set_fmt for the two sides to see if
> they can agree, that both can support what has been asked.
> 
> The pcm512x driver just saves the fmt and say back to that card:
> whatever, I'm fine with it. But runtime during hw_params it can fail due
> to unsupported bus format, which it actually acked to be ok.
> 
> This is the difference.
> 
> Sure, some device have constraint based on the fmt towards the hw_params
> and it is perfectly OK to do such a checks and rejections or build
> rules/constraints based on fmt, but failing hw_params just because
> set_fmt did not checked that the bus format is not even supported is not
> a nice thing to do.

Those are good arguments

>> Would you agree?
> 
> I don't have a device to test, I'm just trying to point out what is the
> right thing to do.

I have a device to test. I will move format checks into `pcm512x_set_fmt()`,
ensure that it works properly, and submit as patch v3.

> I don't buy the argument that the sequencing is important here for the
> register writes. The fmt is set only once and those registers will be
> only written once.
> 
>>> I would also add DSP_A and DSP_B modes at the same time, DSP_A would
>>> need a write of 1 to register 41 (PCM512x_I2S_2, offset = 1), other
>>> formats should set the offset to 0.
>>
>> That's a good idea, than you for technical details! I just didn't know how to
>> use DSP_A and DSP_B. I will add them, and submit as patch v2
> 
> Great!
> Thanks
> - Péter
> 
>> Best regards,
>> Kirill
>>
>> On 11/10/2020 07:59 AM, Peter Ujfalusi wrote:
>>>
>>>
>>> On 09/11/2020 23.21, Kirill Marinushkin wrote:
>>>> Currently, pcm512x driver supports only I2S data format.
>>>> This commit adds RJ and LJ as well.
>>>>
>>>> I don't expect regression WRT existing sound cards, because:
>>>>
>>>> * default value in corresponding register of pcm512x codec is 0 ==  I2S
>>>> * existing in-tree sound cards with pcm512x codec are configured for I2S
>>>> * i don't see how existing off-tree sound cards with pcm512x codec could be
>>>>   configured differently - it would not work
>>>> * tested explicitly, that there is no regression with Raspberry Pi +
>>>>   sound card `sound/soc/bcm/hifiberry_dacplus.c`
>>>>
>>>> Signed-off-by: Kirill Marinushkin <kmarinushkin@xxxxxxxxxx>
>>>> Cc: Mark Brown <broonie@xxxxxxxxxx>
>>>> Cc: Takashi Iwai <tiwai@xxxxxxxx>
>>>> Cc: Liam Girdwood <lgirdwood@xxxxxxxxx>
>>>> Cc: Matthias Reichl <hias@xxxxxxxxx>
>>>> Cc: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
>>>> Cc: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
>>>> Cc: alsa-devel@xxxxxxxxxxxxxxxx
>>>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>>>> ---
>>>>  sound/soc/codecs/pcm512x.c | 24 ++++++++++++++++++++++++
>>>>  1 file changed, 24 insertions(+)
>>>>
>>>> diff --git a/sound/soc/codecs/pcm512x.c b/sound/soc/codecs/pcm512x.c
>>>> index 8153d3d01654..c6e975fb4a43 100644
>>>> --- a/sound/soc/codecs/pcm512x.c
>>>> +++ b/sound/soc/codecs/pcm512x.c
>>>> @@ -1167,6 +1167,7 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
>>>>  	struct snd_soc_component *component = dai->component;
>>>>  	struct pcm512x_priv *pcm512x = snd_soc_component_get_drvdata(component);
>>>>  	int alen;
>>>> +	int afmt;
>>>>  	int gpio;
>>>>  	int clock_output;
>>>>  	int master_mode;
>>>> @@ -1195,6 +1196,22 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
>>>>  		return -EINVAL;
>>>>  	}
>>>>  
>>>> +	switch (pcm512x->fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
>>>> +	case SND_SOC_DAIFMT_I2S:
>>>> +		afmt = PCM512x_AFMT_I2S;
>>>> +		break;
>>>> +	case SND_SOC_DAIFMT_RIGHT_J:
>>>> +		afmt = PCM512x_AFMT_RTJ;
>>>> +		break;
>>>> +	case SND_SOC_DAIFMT_LEFT_J:
>>>> +		afmt = PCM512x_AFMT_LTJ;
>>>> +		break;
>>>> +	default:
>>>> +		dev_err(component->dev, "unsupported DAI format: 0x%x\n",
>>>> +			pcm512x->fmt);
>>>> +		return -EINVAL;
>>>> +	}
>>>> +
>>>
>>> The bus format and
>>>
>>>>  	switch (pcm512x->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
>>>
>>>>  	case SND_SOC_DAIFMT_CBS_CFS:
>>>>  		ret = regmap_update_bits(pcm512x->regmap,
>>>
>>> the clock generation role should be set in pcm512x_set_fmt(), in that
>>> way you can deny specific setups earlier.
>>>
>>> I would also add DSP_A and DSP_B modes at the same time, DSP_A would
>>> need a write of 1 to register 41 (PCM512x_I2S_2, offset = 1), other
>>> formats should set the offset to 0.
>>>
>>>> @@ -1236,6 +1253,13 @@ static int pcm512x_hw_params(struct snd_pcm_substream *substream,
>>>>  		return ret;
>>>>  	}
>>>>  
>>>> +	ret = regmap_update_bits(pcm512x->regmap, PCM512x_I2S_1,
>>>> +				 PCM512x_AFMT, afmt);
>>>> +	if (ret != 0) {
>>>> +		dev_err(component->dev, "Failed to set data format: %d\n", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>>  	if (pcm512x->pll_out) {
>>>>  		ret = regmap_write(pcm512x->regmap, PCM512x_FLEX_A, 0x11);
>>>>  		if (ret != 0) {
>>>>
>>>
>>> - Péter
>>>
>>> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
>>> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>>>
> 
> 
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
>