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

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Date:   Tue, 18 Feb 2020 07:32:11 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Peter Ujfalusi <peter.ujfalusi@...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

* Peter Ujfalusi <peter.ujfalusi@...com> [200218 15:16]:
> 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?

Right, I'm all go for better solutions :)

> >>>> 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...

OK, but so what's the machine driver part in this case?

Regards,

Tony