Re: More Generic Audio Graph Sound Card idea

From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
To: Sameer Pujar <spujar@nvidia.com>
Cc: Linux-ALSA <alsa-devel@alsa-project.org>,
	Mark Brown <broonie@kernel.org>,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	jonathanh@nvidia.com
Subject: Re: More Generic Audio Graph Sound Card idea
Date: 21 Aug 2020 16:14:36 +0900	[thread overview]
Message-ID: <87imdczd4i.wl-kuninori.morimoto.gx@renesas.com> (raw)
In-Reply-To: <097e3fc4-4a84-e101-e6b6-045c3e9e5bfc@nvidia.com>

Hi Sameer
Cc Mark

Thank you for your feedback

> > Current audio-graph-card driver has DPCM support,
> > but it is limited (= Mix/Mux/TDM-split/rate-convert/channel-convert).
> > It was expanded forcibly expanded.
> 
> Yes it appears to be so. Right now it does not seem to be supporting
> 'demux' kind of use case.

I'm not sure how to do demux.
By DPCM ? by multi-Codec ?
I'm happy to consider it if there was sample code.

> Please note that asoc_simple_init_dai_link_params() makes the link
> codec-to-codec if any component involved has 'non_legacy_dai_naming'
> flag enabled. It is used by both audio-graph and simple-card. So it is
> a combination of three (DPCM, normal and codec-to-codec). To avoid all
> this complication, I am treating all links as DPCM in the series [0] I
> sent.

Ahh, we want to consider codec-to-codec..
And I noticed multi-CPU / multi-Codec case too (= for normal connection).
Do we have sample code ? > Mark

> If we encode use case information in DT, it would become regid and is
> not flexible when the HW is giving us the all flexibility (at least in
> my case). Thus may lead to complications. If there is a way to
> configure PCM parameters from the user space it would help to simplify
> things. Then DT can just describe the HW links.

What kind of PCM parameters you want to get from user-space ?

Mark, this is question from me.
In my understanding,
CPU - Codec are merging each parameter automatically at runtime,
for example rates / channels / formats (= snd_soc_runtime_calc_hw()).
And system-clock / TDM-slot / DAI-format are specified via Sound Card.

I can understand that system-clock is specified via Sound Card,
but TDM-slot / DAI-format can be adjusted from CPU / Codec driver
automatically same as rates / channels / formats ?
I'm not sure it is possible, or not, but I've been wondering for a long time.

Thank you for your help !!

Best regards
---
Kuninori Morimoto