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Date:   Tue, 18 Feb 2020 22:16:31 +0100
From:   Sebastian Reichel <sre@kernel.org>
To:     Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc:     Tony Lindgren <tony@atomide.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
        Mark Brown <broonie@kernel.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org,
        Aaro Koskinen <aaro.koskinen@iki.fi>,
        "Arthur D ." <spinal.by@gmail.com>,
        Jarkko Nikula <jarkko.nikula@bitmer.com>,
        Merlijn Wajer <merlijn@wizzup.org>, Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH] ASoC: ti: Allocate dais dynamically for TDM and audio
 graph card
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Hi,

On Tue, Feb 18, 2020 at 02:43:19PM +0200, Peter Ujfalusi wrote:
> On 18/02/2020 1.10, Tony Lindgren wrote:
> > * Peter Ujfalusi <peter.ujfalusi@ti.com> [200217 12:10]:
> >> On 14/02/2020 19.03, Tony Lindgren wrote:
> >>> But right now in droid4 voice call case mcbsp is just the i2s transpo=
rt,
> >>> and everything happens betwee the modem and the cpcap pmic.
> >>
> >> Iow you don't need McBSP DAI at all. If you would have added the dummy
> >> codec to McBSP !3 and use that, it would work in a same way, or to DMIC
> >> or McPDM...
> >>
> >> The McBSP ops are NULL for the dummy dai, so McBSP is turned off.
> >=20
> > Hmm yeah I don't know if the cpcap codec on the same mcbsp needs
> > mcbsp for voice call.
> >=20
> > According to Sebastian sounds like mcbsp can be idle at that point.
> >=20
> > But what about capture of voice call at the mcbsp from the
> > TDM slot? In that case mcbsp would be active.
>=20
> Sure, but with the dummy dai it won't....
>=20
> If I understand correctly the HW setup:
> McBSP2 -> CPCAP_hifi (only playback)
>
> CPCAP_voice is the i2s clock master.
> McBSP3, CPCAP_voice, MDM6600 and WL1285 are all connected together via
> i2s lines.
>=20
> In case of Voice call with analog mic/speaker only CPCAP_voice and
> MDM6600 is used.
> In case of Voice call with BT only MDM6600 and WL1285 is used (but
> CPCAP_voice must provide the clocks?)
> In case you would have any algorithm running on OMAP4 for the calls,
> then you will have McBSP3 inserted and used between MDM6600 and
> CPAC_voice/WL1285.
> Similarly, if you would like to tap in and record the data from the bus
> you will have McBSP3 enabled.
>=20
> The simplest use cases you want to support:
> A. McBSP3 <-> CPCAP_voice (playback/capture)
> B. MDM6600 <-> CPCAP_voice (handset mic/speaker voice call)
> C. MDM6600 <-> WL1285 (BT voice call)
> D. McBSP3 <-> BT (VoIP?)

Your description matches my understanding of the hardware setup.

> I would not bother with recording the call as you would need tom
> reconfigure the McBSP playback pin (is it even possible) as input to
> OMAP4, I think..
>=20
> B/C is codec2codec, McBSP3 is not involved at all.
> A/D is when McBSP3 is used only.
>=20
> Imho this can be represented as
> McBSP2: 1 port
> 	1.1: to CPCAP_hifi
>=20
> McBSP3: 1 port, 2 endpoint
> 	2.1: to CPCAP_voice
> 	2.2: to WL1285
> CPCAP: 2 ports
> 	hifi:	3.1: to McBSP2
> 	voice:	4.1: to McBSP3
> 		4.2: to MDM6600
> MDM6600: 2 ports

I suppose you mean 1 port, 2 endpoints?

> 	5.1: to CPAC_voice
> 	5.2: to WL1285
> WL1285: 2 ports

and here too?

> 	6.1: to McBSP3
> 	6.2: to MDM6600
>=20
> The machine driver should switch between the graph links based on the
> use case for the interconnected devices:
> A: 2.2 <-> 4.1
> B: 4.2 <-> 5.1
> C: 6.2 <-> 5.1
> D: 2.2 <-> 6.1
>=20
> Can a generic card provide such a functionality?

I suppose in the end its a question if generic card can provide TDM
support.

> In case of B/C you should not have a running stream imho.

I would expect, that MDM6600 codec marks itself as running/stopped
based on call state. That should enable DAPM widgets automatically
when CPCAP_voice is routed to MDM6600?

> In all cases CPCAP_voice should be able to run the clocks on i2s,
> even if it is not used by the audio setup.
> Not sure if you can just turn Wl1285 as master, but it is possible
> that it is master, but silent when it is not used?

I provided CPCAP registers for BT call, which should be enough to
figure this out (I did not yet analyze the results myself).

> I'm not sure if we should span out dummy dais for endpoints within a
> port. Imho the port _is_ the dai. Different endpoints might use
> different TDM slots on the port (or the same slot, which makes them
> exclusive).

Makes sense to me.

-- Sebastian

> >>>>>> I know it was discussed, but can not find the mail:
> >>>>>> Can you brief again on the audio connection?
> >>>>>
> >>>>> Below is a link to a mailing list thread where Sebastian describes
> >>>>> the audio connection:
> >>>>>
> >>>>> https://lkml.org/lkml/2018/3/28/881
> >>>>
> >>>> Thanks!
> >>>> =20
> >>>>>> Do you have branch with working code?
> >>>>>
> >>>>> Yeah I have slightly older set of the patches in my droid4-pending-=
v5.5
> >>>>> kernel.org git branch with voice calls working.
> >>>>
> >>>> I think I should put my droid4 out and try to get it working...
> >>>> Do you have a link for dummies to follow to get started? ;)
> >>>
> >>> Probably the easiest one to use right now is the Maemo-leste devuan b=
ased
> >>> test image using v5.5 kernel + modem and audio patches:
> >>>
> >>> https://leste.maemo.org/Motorola_Droid_4
> >>>
> >>> Just use a decent speed micro-sd card rated "a1" for example.
> >>
> >> Cool. Now I can dual boot the droid4 :D
> >> I needed to rewrite the /etc/shadow to get a known root password so I
> >> can log in.
> >=20
> > Not sure if you mean password for the droid4-kexecboot or the
> > Linux distro you installed..
>=20
> It was for the maemo-leste.
> Bringing up Gentoo will be a bit harder as I don't have wifi stuff in my
> reference image...
>=20
> > But for droid4-kexecboot, you
> > can configure it to automatically download new kernels over wlan.
> > There's some info on the machine specific password and how to
> > configure wlan in the droid4-kexecboot buildroot commits here:
> >=20
> > https://github.com/tmlind/buildroot/commits/droid4-kexecboot-2017.11
> >=20
> >> Wifi is up, so in theory I can scp kernel/dtb to /boot/boot/ and update
> >> the /boot/boot/boot.cfg to boot my kernel, right?
> >=20
> > Yeah you can update kernels and modules over wlan from the distro(s)
> > you have configured, and also from droid4-kexecboot as above.
>=20
> I need to try droid4-kexecboot's wifi support then.
>=20
> > And note that kexecboot looks for a boot/boot.cfg file to use on
> > every usable parition it finds and uses all the found entries
> > based on the priority configured for the boot.cfg entry.
>=20
> OK, thanks!
>=20
> >=20
> > Regards,
> >=20
> > Tony
> >=20
>=20
> - P=E9ter
>=20
> Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
> Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

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