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Subject: Re: [RFC PATCH 3/5] HACK: ASoC: Tolerate N-cpus-to-M-codecs links
From:   =?utf-8?Q?Martin_Povi=C5=A1er?= <povik@cutebit.org>
In-Reply-To: <YmamSZKNtNai7KyM@sirena.org.uk>
Date:   Mon, 25 Apr 2022 15:55:32 +0200
Cc:     =?utf-8?Q?Martin_Povi=C5=A1er?= <povik+lin@cutebit.org>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>,
        Takashi Iwai <tiwai@suse.com>, alsa-devel@alsa-project.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Mark Kettenis <kettenis@openbsd.org>,
        Hector Martin <marcan@marcan.st>,
        Sven Peter <sven@svenpeter.dev>
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To:     Mark Brown <broonie@kernel.org>
Precedence: bulk


> On 25. 4. 2022, at 15:46, Mark Brown <broonie@kernel.org> wrote:
>=20
> On Mon, Apr 25, 2022 at 03:11:14PM +0200, Martin Povi=C5=A1er wrote:
>>> On 25. 4. 2022, at 14:55, Mark Brown <broonie@kernel.org> wrote:
>=20
>>> I am surprised that doesn't otherwise explode TBH - at the very =
least
>>> I'd expect it to show two PCMs to userspace which if I'm =
understanding
>>> your description correctly isn't really what's going on.
>=20
>> I fill in a single snd_soc_dai_link, it exposes a single PCM and =
works
>> like a charm. That is as long as I patch the playback/capture check =
in
>> question.
>=20
>> I read that to be the clear intention of ASoC code: a DAI link =
becomes
>> one snd_soc_pcm_runtime.
>=20
> Yes, so long as you boil it down to a single link it works fine but =
the
> bit on top of the binding where you tie the two CPU DAIs to what is
> actually exposed is all in code.  The reason this stuff isn't filled =
in
> is that connecting the thing that applications see to the physical =
links
> isn't at all obvious and needs at least some driver sitting in the
> middle to make the links - I'd imagine there's a DSP sitting there =
which
> probably has quite a bit of flexability about how the various hardware
> components available are actually related.  This makes figuring out =
what
> to do with the relationship between the multiple CPU DAIs hard.

I get the gist. Anyway unless you tell me otherwise I will assume I need
to move to DPCM with the platform/machine driver.