linux-kernel - Re: [PATCH v2 2/3] bindings: sound: Add documentation for TI j721e EVM (CPB and IVI)

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Message-ID: <d0496765-918c-766b-825c-76eb2f76c274@ti.com>
Date:   Wed, 20 May 2020 12:59:57 +0300
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     Rob Herring <robh@...nel.org>
CC:     <broonie@...nel.org>, <lgirdwood@...il.com>,
        <alsa-devel@...a-project.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/3] bindings: sound: Add documentation for TI j721e
 EVM (CPB and IVI)

Hi Rob,

On 20/05/2020 1.42, Rob Herring wrote:
> On Tue, May 12, 2020 at 04:16:32PM +0300, Peter Ujfalusi wrote:
>> The audio support on the Common Processor Board board is using
>> pcm3168a codec connected to McASP10 serializers in parallel setup.
>>
>> The Infotainment board plugs into the Common Processor Board, the support
>> of the extension board is extending the CPB audio support by adding
>> the two codecs on the expansion board.
>>
>> The audio support on the Infotainment Expansion Board consists of McASP0
>> connected to two pcm3168a codecs with dedicated set of serializers to each.
>> The SCKI for pcm3168a is sourced from j721e AUDIO_REFCLK0 pin.
> 
> Would the audio graph card work for you on this?

Unfortunately not.
The CPB and IVI while using different McASP (10 for CPB, 0 for IVI) and
different clock pin is used for the SCKI of the codecs on CPB and IVI,
they are actually coming from the same source from within the SoC.
The inter-dependency between the two audio domains are fragile and I
have spent countless hours to figure out a way to masquerade the unique
setup as generic. Did not worked out, it needs a custom machine driver
to be able to handle the setup.

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

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