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

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Date:   Thu, 20 Feb 2020 21:47:33 +0100
From:   Sebastian Reichel <sre@...nel.org>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     Tony Lindgren <tony@...mide.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.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

Hi,

On Thu, Feb 20, 2020 at 04:15:22PM +0200, Peter Ujfalusi wrote:
> > I suppose in the end its a question if generic card can provide TDM
> > support.
> 
> Sure it can, but can it handle the switching between the paths based on
> use cases?
> There should be machine level DAPM widgets to kick codec2codec (MDM6600
> - CPAC_voice for example) and also to make sure that when you switch
> between them the system is not going to get misconfigured.
> Switching between CPAC and BT route during call?
> Not allowing VoIP while on call, etc.

I think the main issue is, that based on the route configuration
(which could be a simple DAPM widget generated by the simple-graph-card),
we may need to configure different bitrates. Tony's hack adding
this knowledge to the cpcap driver is very ugly.

> >> 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 got the datasheet from NXP (thanks for the pointer!), I try to look at
> it in a coming days.

FWIW the datasheet is not for the same chip, but for a similar one.
The audio part seems to be very similar though.

-- Sebastian

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