linux-kernel - Re: [PATCH RFC 2/3] ASoC: audio-graph-card2: support explicitly disabled links

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Message-ID: <871psls8nw.wl-kuninori.morimoto.gx@renesas.com>
Date: Mon, 19 May 2025 01:15:16 +0000
From: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To: Mihalcea Laurentiu <laurentiumihalcea111@...il.com>
Cc: Mark Brown <broonie@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-sound@...r.kernel.org
Subject: Re: [PATCH RFC 2/3] ASoC: audio-graph-card2: support explicitly disabled links


Hi Mihalcea

Thank you for clarify details.

> [snippet from base.dts]
> 
> 	my_card: card {
> 		compatible = "audio-graph-card2";
> 		links = <&l2>; /* here, we're only allowed to specify links that exist */
> 		routing = "Headphones", "C20",
> 			  "Headphones", "C21",
> 			  "Line", "C01";
> 	};
(snip)
> &my_card {
> 	/* here we're forced to also specify l2 even if this is already done
>          * in base.dts. This is because DT overlays don't support appending to
> 	 * properties.
>          */
> 	remote-endpoint = <&l0>, <&l1>, <&l2>;
> };

This is very nit pickking, but I need to confirm.
You want to indicate here is this ?

	&my_card {
-		remote-endpoint = <&l0>, <&l1>, <&l2>;
+		links = <&l0>, <&l1>, <&l2>;
	};

> &l0_ep {
> 	remote-endpoint = <&c1_ep>;
> };
> 
> &l1_ep {
> 	remote-endpoint = <&c2_ep>;
> };
> 
> c0: codec@0 {
> 	port { c0_ep: endpoint { remote-endpoint = <&l0_ep>; } };
> };
> 
> c1: codec@1 {
> 	port { c1_ep: endpoint { remote-endpoint = <&l1_ep>; } };
> };

This is also nit pickking, but I think above is wrong.
I guess you want to indicate is...

	&l0_ep {
-		remote-endpoint = <&c1_ep>;
+		remote-endpoint = <&c0_ep>;
	};

	&l1_ep {
-		remote-endpoint = <&c2_ep>;
+		remote-endpoint = <&c1_ep>;
	};


Your are indicating very confusable naming, so I want to understand
correctly as much as possible.

> >> 	CODEC A has widgets A0, A1.
> >> 	CODEC B has widgets B0, B1.
> >>
> >> 	my-card {
> >> 		compatible = "audio-graph-card2":
> >> 		label = "my-label";
> >> 		links = <&cpu0_port>, <&cpu1_port>;
> >> 		routing = "A0", "A1",
> >> 		          "B0", "B1";
> >> 	};
> >>
> >> 	CODEC A's DT node was disabled.
> >> 	CODEC B's DT node is enabled.
> >> 	CPU0's DT node is enabled.
> >> 	CPU1's DT node is enabled.
(snip)
> Assume that we also have BASE1 that is compatible with PLUGIN but
> C0 and C1 are connected to BASE1's D0 and D5. Since there's no D1-C1
> connection that means you'll have to create another DT overlay. Thus,
> the scalability of plugin.dtso decreases.
> 
> Now, for our particular case, we have BASE0 and BASE1 with the following
> DAIs and CODECS (these are physically present on the base boards):
> 
> BASE0 has DAIs D0, D1 and CODEC C0
> BASE1 has DAIs D0, D1 and CODEC C1
> 
> Both of these boards are compatible with plugin PLUGIN that has codec C2.
> The possible DAI links are:
> 
> For BASE0:
> 
> D0 <----> C0
> D1 <----> C2 (only possible with PLUGIN connected)
> 
> For BASE1:
> 
> D0 <----> C1
> D1 <----> C2 (only possible with PLUGIN connected)
> 
> Since the D1 <---> C2 connection is valid for both BASE0-PLUGIN and
> BASE1-PLUGIN combinations I think we can make do without the support
> for explicitly disabled links. But I don't think this is ideal because:

Let's avoid BASE3 case here to avoid _if_ story.
You are now indicating too many complex/cofusable situations with wrong
setting samples (D0/D1/D2..., C0/C1/C2. BASEx has no D1-C1..., etc, etc...)

I noticed that why you need to add disabled Codec routing on BASE DT ?
It is the reason why you can't detect BASE only sound card, right ?

	---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ----
[snippet from base.dts]

	my_card: card {
		compatible = "audio-graph-card2";
		links = <&l2>; /* here, we're only allowed to specify links that exist */
		routing = "Headphones", "C20",
			  "Headphones", "C21",
=>			  "Line", "C01";
	};

	---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ----

If my understanding was correct, your system can be indicated like below
(It is not same as your D0/D1/D2 sample, but I think same things, and
 not confusable sample)

	BASE			  PLUGIN
	+-----------------+
	| CPU0 <-> Codec0 |     +--------+
	| CPU1		  | <-> | Codec1 |
	| CPU2		  | <-> | Codec2 |
	+-----------------+     +--------+

How it works by below ?

BASE
	/*
	 * detect CPU0-Codec0 connection only
	 * Codec1/2 are disabled, but not related to BASE
	 */
	my_card: card {
		links = <&cpu0>;
		routing = "Headphone0", "Codec0"; /* for CPU0-Codec0 */
	};

PLUGIN
	/* detect all
	 * CPU0-Codec0 connection
	 * CPU1-Codec1 connection
	 * CPU2-Codec2 connection, and its routings */
	&my_card {
		links = <&cpu0>, <&cpu1>, <&cpu2>;
		routing = "Headphone0", "Codec0", /* for CPU0-Codec0 */
			  "Headphone1", "Codec1", /* for CPU1-Codec1 */
			  "Headphone2", "Codec2"; /* for CPU2-Codec2 */
	};


And/Or your situation is similar as mine (I should have noticed
about this sooner).

	d70be079c3cf34bd91e1c8f7b4bc760356c9150c
	("arm64: dts: renesas: ulcb/kf: Use multi Component sound")

	547b02f74e4ac1e7d295a6266d5bc93a647cd4ac
	("ASoC: rsnd: enable multi Component support for Audio Graph Card/Card2")

	45655ec69cb954d7fa594054bec33d6d5b99f8d5
	("ASoC: soc-core.c: enable multi Component")

My board is handling above sample as 2 cards, by using "multi Component"

	BASE			  PLUGIN
	+-----------------+			^
	| CPU0 <-> Codec0 |			| Card1
	|		  |			v
	|		  |     +--------+	^
	| CPU1		  | <-> | Codec1 |	| Card2
	| CPU2		  | <-> | Codec2 |	|
	+-----------------+     +--------+	v


Thank you for your help !!

Best regards
---
Kuninori Morimoto