linux-kernel - Re: [PATCH] ASoC: ti: Allocate dais dynamically for TDM and audio graph card

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Date:   Fri, 14 Feb 2020 09:09:46 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Sebastian Reichel <sre@...nel.org>
Cc:     Peter Ujfalusi <peter.ujfalusi@...com>,
        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,
        Aaro Koskinen <aaro.koskinen@....fi>,
        "Arthur D ." <spinal.by@...il.com>,
        Jarkko Nikula <jarkko.nikula@...mer.com>,
        Merlijn Wajer <merlijn@...zup.org>, Pavel Machek <pavel@....cz>
Subject: Re: [PATCH] ASoC: ti: Allocate dais dynamically for TDM and audio
 graph card

* Sebastian Reichel <sre@...nel.org> [200214 13:05]:
> On Thu, Feb 13, 2020 at 05:34:54PM -0800, Tony Lindgren wrote:
> > And bluetooth would be similar to cpcap_audio and mot_mdm6600_audio
> > above.
> 
> My understanding is, that CPU is not involved for calls (except for
> setting up cpcap registers correctly). Basically McBSP3 should
> remain idle for a call and data goes directly from modem to cpcap.
> The same should work for modem <-> BT, except that CPCAP seems to
> always provide the clock. That would imply a direct link between
> modem and codec / BT?

Yes the direct link is i2s. I'm ot sure if mcbsp can be idle during
voice call though, I guess it should be doable since mcbsp is not
the clock master :)

> > My guess is that only cpcap registers and clock rate needs to be
> > changed for bluetooth audio BTW, so if somebody havs a bluetooth
> > headset just do the following in Android:
> > 
> > # cpcaprw --all > /tmp/before
> > configure bluetooth headset for audio in android and start
> > playing some music or make a phone call
> > ...
> > # cpcaprw --all > /tmp/after
> > stop playing music or phone call
> > ...
> > diff -u /tmp/before /tmp/after
> > 
> > The registers will be different for a bluetooth phone call and
> > playing music.
> 
> I can provider register values once I find some time.

OK great.

Regards,

Tony