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

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Message-ID: <874ixltjzw.wl-kuninori.morimoto.gx@renesas.com>
Date: Fri, 16 May 2025 01:36:04 +0000
From: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To: Laurentiu Mihalcea <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 Laurentiu

Thank you for the patch

> An explicitly disabled link is a DAI link in which one of its device
> endpoints (e.g: codec or CPU) has been disabled in the DTS via the
> "status" property. Formally speaking:
> 
> 	OF_LINK_IS_DISABLED(lnk) = OF_NODE_IS_DISABLED(dev0) ||
> 	                           OF_NODE_IS_DISABLED(dev1);
> 
> where dev0 and dev1 are the two devices (CPU/codec) that make up the
> link.
> 
> If at least one link was explicitly disabled that means DAPM routes
> passed through the OF property "routing" can fail as some widgets might
> not exist. Consider the following example:
> 
> 	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.
> 
> If CODEC A's DT node is disabled via the 'status = "disabled"' property
> that means the A0 -> A1 route cannot be created. This doesn't affect the
> B0 -> B1 route though as CODEC B was never disabled in the DT.
> 
> This is why, if any explicitly disabled link is discovered, the
> "disable_of_route_checks" flag is turned on.
> 
> If all links were explicitly disabled the sound card creation will fail.
> Otherwise, if there's at least one link which wasn't explicitly disabled
> then the sound card creation will succeed.
> 
> Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@....com>
> ---

I think I could understand your situation, but the solution (= this patch) is
too much complicated for me. Indeed it might detect disabled device, but some
board might want to detect it as error, unlike your case.

You want to add "disable_of_route_checks" flag to the card, right ?
How about to add new property, like "force detect xxx", or
"DAI might not be detected", etc, etc, etc...

If we can have such property, it will be more simple code.

	if (it_has_flag("force_detect_xxx")) {
		dev_info(dev, "xxx");
		card->disable_of_route_checks = 1;
	}

Thank you for your help !!

Best regards
---
Kuninori Morimoto