linux-kernel - Re: [PATCH] ASoC: cpcap: Implement set_tdm

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Message-ID: <8fc1dded-6d28-f5cd-f2f9-3a6810571119@ti.com>
Date:   Tue, 18 Feb 2020 17:15:52 +0200
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     Tony Lindgren <tony@...mide.com>
CC:     Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, <alsa-devel@...a-project.org>,
        <linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
        "Arthur D ." <spinal.by@...il.com>,
        Merlijn Wajer <merlijn@...zup.org>,
        Pavel Machek <pavel@....cz>,
        Sebastian Reichel <sre@...nel.org>,
        Jarkko Nikula <jarkko.nikula@...mer.com>
Subject: Re: [PATCH] ASoC: cpcap: Implement set_tdm_slot for voice call
 support

Hi Tony,

On 18/02/2020 1.23, Tony Lindgren wrote:
> * Peter Ujfalusi <peter.ujfalusi@...com> [200214 13:30]:
>> Hi Tony,
>>
>> On 12/02/2020 16.46, Tony Lindgren wrote:
>>> * Peter Ujfalusi <peter.ujfalusi@...com> [200212 09:18]:
>>>> On 11/02/2020 20.10, Tony Lindgren wrote:
>>>>> +static int cpcap_voice_set_tdm_slot(struct snd_soc_dai *dai,
>>>>> +				    unsigned int tx_mask, unsigned int rx_mask,
>>>>> +				    int slots, int slot_width)
>>>>> +{
>>>>> +	struct snd_soc_component *component = dai->component;
>>>>> +	struct cpcap_audio *cpcap = snd_soc_component_get_drvdata(component);
>>>>> +	int err, ts_mask, mask;
>>>>> +	bool voice_call;
>>>>> +
>>>>> +	/*
>>>>> +	 * Primitive test for voice call, probably needs more checks
>>>>> +	 * later on for 16-bit calls detected, Bluetooth headset etc.
>>>>> +	 */
>>>>> +	if (tx_mask == 0 && rx_mask == 1 && slot_width == 8)
>>>>> +		voice_call = true;
>>>>> +	else
>>>>> +		voice_call = false;
>>>>
>>>> You only have voice call if only rx slot0 is in use?
>>>
>>> Yeah so it seems. Then there's the modem to wlcore bluetooth path that
>>> I have not looked at. But presumably that's again just configuring some
>>> tdm slot on the PMIC.
>>>
>>>> If you record mono on the voice DAI, then rx_mask is also 1, no?
>>>
>>> It is above :) But maybe I don't follow what you're asking here
>>
>> If you arecrod -Dvoice_pcm -c1 -fS8 > /dev/null
>> then it is reasonable that the machine driver will set rx_mask = 1
>>
>>> and maybe you have some better check in mind.
>>
>> Not sure, but relying on set_tdm_slots to decide if we are in a call
>> case does not sound right.
> 
> OK yeah seems at least bluetooth would need to be also handled
> in the set_tdm_slots.

set_tdm_slots() is for setting how the TDM slots supposed to be used by
the component and not really for things to configure different operating
modes.

If you hardwire things in set_tdm_slots() for the droid4 then how the
codec driver can be reused in other setups?

>>>> You will also set the sampling rate for voice in
>>>> cpcap_voice_hw_params(), but that is for normal playback/capture, right?
>>>
>>> Yeah so normal playback/capture is already working with cpcap codec driver
>>> with mainline Linux. The voice call needs to set rate to 8000.
>>
>> But if you have a voice call initiated should not the rate be set by the
>> set_sysclk()?
> 
> Hmm does set_sysclk called from modem codec know that cpcap codec
> is the clock master based on bitclock-master and set the rate
> for cpcap codec?

Neither component should call set_sysclk, set_tdm_slots. The machine
driver should as it is the only one who know how things are wired...

> 
>>>> It feels like that these should be done via DAPM with codec to codec route?
>>>
>>> Sure if you have some better way of doing it :) Do you have an example to
>>> point me to?
>>
>> Something along the lines of:
>> https://mailman.alsa-project.org/pipermail/alsa-devel/2020-February/162915.html
>>
>> The it is a matter of building and connecting the DAPM routes between
>> the two codec and with a flip of the switch you would have audio flowing
>> between them.
> 
> Sounds good to me.
> 
> Tony
> 

- Péter

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