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Date: Thu, 12 Nov 2020 08:57:06 +0100
From: Kirill Marinushkin <kmarinushkin@...dec.com>
To: Peter Ujfalusi <peter.ujfalusi@...com>
Cc: Mark Brown <broonie@...nel.org>, Takashi Iwai <tiwai@...e.com>,
Liam Girdwood <lgirdwood@...il.com>,
Matthias Reichl <hias@...us.com>,
Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: pcm512x: Add support for data formats RJ and LJ
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@...dec.com>
>>>> Cc: Mark Brown <broonie@...nel.org>
>>>> Cc: Takashi Iwai <tiwai@...e.com>
>>>> Cc: Liam Girdwood <lgirdwood@...il.com>
>>>> Cc: Matthias Reichl <hias@...us.com>
>>>> Cc: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
>>>> Cc: Peter Ujfalusi <peter.ujfalusi@...com>
>>>> Cc: alsa-devel@...a-project.org
>>>> Cc: linux-kernel@...r.kernel.org
>>>> ---
>>>> 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
>
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