linux-kernel - Re: [RFC PATCH] soc: audio-graph-card2: use correct endpoint when getting link parameters

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Message-ID: <87y0zdsxme.wl-kuninori.morimoto.gx@renesas.com>
Date: Tue, 14 Jan 2025 06:44:25 +0000
From: Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>
To: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
Cc: lgirdwood@...il.com,
	broonie@...nel.org,
	perex@...ex.cz,
	tiwai@...e.com,
	tony@...mide.com,
	alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH] soc: audio-graph-card2: use correct endpoint when getting link parameters


Hi Ivaylo

Sorry for the late review.

> We may have multiple links between ports, with each link
> having different parameters. Currently, no matter the topology,
> it is always port endpoint 0 that is used when setting parameters.
> 
> On a complex sound system, like the one found on Motorola droid4,
> hifi and voice DAIs require differents formats (i2s vs dsp_a)
> and curently it is impossible to use DT to set that.
>  
> Implementing the change leads to partially dropping of at least
> 0dedbde5062d (ASoC: cpcap: Implement set_tdm_slot for voice call
> support), as core does most of what is needed to configure voice DAI.
> 
> We (on Maemo Leste ) use the patch (along with few others) to have
> voice calls working properly on d4 through UCM.
> 
> The patch is for linux 6.6, I want to know whether the
> approach would be accepted before sending a proper patch for
> current master.
> 
> the original commit message follows:
> 
> When link parameters are parsed, it is always endpoint@0 that is used and
> parameters set to other endpoints are ignored.
> 
> Fix that by using endpoint that is set in DT when parsing link parameters.
> 
> Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
> ---
(snip)
> @@ -684,7 +683,6 @@ int audio_graph2_link_dpcm(struct asoc_simple_priv *priv,
>  {
>  	struct device_node *ep = port_to_endpoint(lnk);
>  	struct device_node *rep = of_graph_get_remote_endpoint(ep);
> -	struct device_node *rport = of_graph_get_remote_port(ep);
>  	struct snd_soc_dai_link *dai_link = simple_priv_to_link(priv, li->link);
>  	struct simple_dai_props *dai_props = simple_priv_to_props(priv, li->link);
>  	int is_cpu = asoc_graph_is_ports0(lnk);
> @@ -718,7 +716,7 @@ int audio_graph2_link_dpcm(struct asoc_simple_priv *priv,
>  		dai_link->dynamic		= 1;
>  		dai_link->dpcm_merged_format	= 1;
>  
> -		ret = graph_parse_node(priv, GRAPH_DPCM, rport, li, 1);
> +		ret = graph_parse_node(priv, GRAPH_DPCM, rep, li, 1);

Please correct me if I was misunderstanding
Is the main issue "remote" side endpoint ?

You want to parse "remote" endpoint (= rep) directly, but the function
requests "port" (= rport), and it will use endpoint0 ( != rep).
Is this the main issue you want to fix ?

Thank you for your help !!

Best regards
---
Kuninori Morimoto