linux-kernel - Re: [PATCH 07/13] ASoC: ti: davinci-i2s: Add TDM support

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Date: Wed, 20 Mar 2024 08:31:10 +0100
From: Bastien Curutchet <bastien.curutchet@...tlin.com>
To: Péter Ujfalusi <peter.ujfalusi@...il.com>,
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>,
 Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>, Jaroslav Kysela <perex@...ex.cz>,
 Takashi Iwai <tiwai@...e.com>
Cc: linux-sound@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, herve.codina@...tlin.com,
 christophercordahi@...ometrics.ca
Subject: Re: [PATCH 07/13] ASoC: ti: davinci-i2s: Add TDM support

Hi Péter,

>> +static int davinci_i2s_set_tdm_slot(struct snd_soc_dai *cpu_dai,
>> +				    unsigned int tx_mask,
>> +				    unsigned int rx_mask,
>> +				    int slots, int slot_width)
>> +{
>> +	struct davinci_mcbsp_dev *dev = snd_soc_dai_get_drvdata(cpu_dai);
>> +
>> +	dev_dbg(dev->dev, "%s - slots %d, slot_width %d\n", __func__, slots, slot_width);
> 
> The __func__ can be ommited, it is better to leave it for dynamic
> debugging by adding "dyndbg=+pmf" module parameter if needed.
> 

True, I'll remove the __func__.

>> +
>> +	if (slots > 128 || !slots) {
>> +		dev_err(dev->dev, "Invalid number of slots\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	if (rx_mask != (1 << slots) - 1) {
>> +		dev_err(dev->dev, "Invalid RX mask (0x%08x) : all slots must be used by McBSP\n",
>> +			rx_mask);
>> +		return -EINVAL;
> 
> This is only a restriction for RX?
> 

Nope you're right, I'll add the same for tx_mask.

>> +	}
>> +
>> +	if (davinci_i2s_tdm_word_length(slot_width) < 0) {
>> +		dev_err(dev->dev, "%s: Unsupported slot_width %d\n", __func__, slot_width);
>> +		return -EINVAL;
>> +	}
>> +
>> +	dev->tdm_slots = slots;
>> +	dev->slot_width = slot_width;
>> +
>> +	return 0;
>> +}
>> +
>>   #define DEFAULT_BITPERSAMPLE	16
>>   
>>   static int davinci_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
>> @@ -228,6 +282,13 @@ static int davinci_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
>>   		DAVINCI_MCBSP_SRGR_FWID(DEFAULT_BITPERSAMPLE - 1);
>>   
>>   	dev->fmt = fmt;
>> +
>> +	if ((dev->tdm_slots || dev->slot_width) &&
>> +	    ((fmt & SND_SOC_DAIFMT_CLOCK_PROVIDER_MASK) != SND_SOC_DAIFMT_BP_FC)) {
>> +		dev_err(dev->dev, "TDM is only supported for BP_FC format\n");
>> +		return -EINVAL;
> 
> I think this is not a valid statement, Fsync can be generated internally
> or coming from external source in TDM mode also.
> 

My hardware allow me to only test BP_FC so I wished to put some
'barriers' in front of untested things.


Best regards,
Bastien