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

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Message-ID: <20200219185302.GC37466@atomide.com>
Date:   Wed, 19 Feb 2020 10:53:02 -0800
From:   Tony Lindgren <tony@...mide.com>
To:     Sebastian Reichel <sebastian.reichel@...labora.com>
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,
        "Arthur D ." <spinal.by@...il.com>,
        Merlijn Wajer <merlijn@...zup.org>,
        Pavel Machek <pavel@....cz>,
        Jarkko Nikula <jarkko.nikula@...mer.com>
Subject: Re: [PATCH] ASoC: cpcap: Implement set_tdm_slot for voice call
 support

* Sebastian Reichel <sebastian.reichel@...labora.com> [200218 17:07]:
> On Tue, Feb 18, 2020 at 07:32:11AM -0800, Tony Lindgren wrote:
> > OK, but so what's the machine driver part in this case?
> 
> simple-graph-card is the current machine driver. We might have to
> introduce a Droid 4 specific driver instead. I used simple(-graph)-card
> instead of introducing a new driver, since the setup was simple enough
> without modem and bluetooth. The simple card was perfect to test the CPCAP
> codec driver. The TDM things might be complex enough to create
> a new machine driver (as I mentioned in the original patchset
> adding CPCAP codec support).

Well we do have the .set_tdm_slot to configure things. If it turns
out we only need to track the machine audio state in cpcap.c, then
we don't need a separate machine driver.

However, if it turns out that cpcap is not always active for
some audio paths, then yeah it seems that we need a custom
machine driver to keep track of the machine audio state.

> Note: Don't use Motorola's tree to learn about ASoC. Their soundcard
> and cpcap codec drivers are full of weird hacks. I'm pretty sure the
> author(s) did not really understand how ASoC works. From my
> experience you should only use their code to understand the
> hardware wiring. You might also want to look into the MC13783
> datasheet for the keyword "network mode".

Yeah nope. And just dumping out the cpcap registers in Android
seems to provide enough information to get the missing features
working.

Regards,

Tony