Re: More Generic Audio Graph Sound Card idea

25 Sep 2020


      Hi
For more generic Auido Graph Sound Card, I'm thinking about
Multi-CPU/Codec now.
(Need to think about Codec-to-Codec later, but it is next task)
I want to know your idea, opinion, etc, etc...
...
...
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
First idea is using "ports".
In such case, I think multi-CPU side is not big issue,
because "dais" selects "port" (and "ports") instead of "endpoint".
(Note: here have no compatible to "-scu-" of audio-graph)
CPU0-1 <------> Codec0
    CPU0-2 <---/
    CPU0-3 <---/
sound {
    	compatible = "audio-graph-card2";
=>		dais = <&cpu0>;
    };
cpu-device {
    	/*
    	 * use "ports" for Multi-CPU
    	 */
=>		cpu0: ports {
    		port@0 { cpu0_1: endpoint { remote-endpoint = <&codec0_1>; }; };
    		port@1 { cpu0_2: endpoint { remote-endpoint = <&codec0_2>; }; };
    		port@2 { cpu0_3: endpoint { remote-endpoint = <&codec0_3>; }; };
    	};
/*
    	 * According to graph.txt, 
    	 * we can use other "port" and/or "ports" for non multi-CPU.
    	 */
    	port@x { };
    	port@x { };
    	ports {
    		port { };
    		...
    	};
    };
codec-device {
    	port {	codec0_1: endpoint@0 { remote-endpoint = <&cpu0_1>; };
    		codec0_2: endpoint@0 { remote-endpoint = <&cpu0_2>; }; 
    		codec0_3: endpoint@0 { remote-endpoint = <&cpu0_3>; }; };
    };
But multi-Codec side is difficult.
Because it is selected via "endpoint" via CPU.
No way to select it via "port" and/or "ports".
CPU1 <------> Codec1-1
            ---> Codec1-2
            ---> Codec1-3
sound {
    	compatible = "audio-graph-card2";
dais = <&cpu1>;
    };
cpu-device {
    	/*
    	 * CPU selects Codec by "endpoints".
    	 */
    	cpu1: port {	cpu1_1: endpoint { remote-endpoint = <&codec1_1>; };
    			cpu1_2: endpoint { remote-endpoint = <&codec1_2>; };
    			cpu1_3: endpoint { remote-endpoint = <&codec1_3>; };
    	};
    };
codec-device {
    	/*
    	 * Codec is selected via CPU.
    	 * It is best if we can select "codec1" (= port / ports) from CPU.
    	 * But is selected via "endpoint" in reality,
    	 * using "ports" is not enough for Multi-Codec.
    	 * because see below
    	 */
    	codec1: ports {
    		port@0 { codec1_1: endpoint { remote-endpoint = <&dai0_0>; }; };
    		port@1 { codec1_2: endpoint { remote-endpoint = <&dai0_1>; }; };
    		port@2 { codec1_3: endpoint { remote-endpoint = <&dai0_2>; }; };
    	};
/*
    	 * Because "ports" is used to for non Multi-xxx too.
    	 * How to know the "ports" was for Multi-xxx or not ?
    	 */
    	ports {
    		port@1 { for device1 };
    		port@2 { for device2 };
    		port@3 { for device3 };
    	};
    };
We might want to select Multi-CPU/Codec by using multi deivces ?
in such case, using "ports" idea is not enough.
Using extra device like DSP can be more generic ?
<--- multi-CPU --->
                *******
    CPU0-1 <--> *     * <--> Codec0
    CPU0-2 <--> *     *
    CPU0-3 <--> *     *
                *******
sound {
    	compatible = "audio-graph-card2";
dais = <&cpu0>;
    };
cpu-device {
    	ports {
    		/* for multi-CPU */
    		port@0 { cpu0_1: endpoint { remote-endpoint = <&multi_cpu_1>; }; };
    		port@1 { cpu0_2: endpoint { remote-endpoint = <&multi_cpu_2>; }; };
    		port@2 { cpu0_3: endpoint { remote-endpoint = <&multi_cpu_3>; }; };
/* for others */
    		port@3 { ... };
    	};
    };
multi-cpu {
    	compatible = "audio-graph-card2-multi";
/* CPU side */
    	cpu0: ports@0 {
    		port@0 { multi_cpu_1: endpoint { remote-endpoint = <&cpu0_1>; }; };
    		port@1 { multi_cpu_2: endpoint { remote-endpoint = <&cpu0_2>; }; };
    		port@2 { multi_cpu_3: endpoint { remote-endpoint = <&cpu0_3>; }; };
    	};
/* Codec side */
    	ports@1 {
    		port@0 { multi_cpu0: endpoint { remote-endpoint = <&codec0>; }; };
    	};
    };
codec-device {
    	ports {
    		port@0 { codec0: endpoint { remote-endpoint = <&multi_cpu0>; }; };
    		port@1 { ... };
    	};
    };
<--- multi-Codec --->
              *******
    CPU1 <--> *     * <--> Codec1-1
              *     * <--> Codec1-2
              *     * <--> Codec1-3
              *******
sound {
    	compatible = "audio-graph-card2";
dais = <&cpu1>;
    };
cpu-device {
    	ports {
    		cpu1: port@0 { cpu1_0: endpoint { remote-endpoint = <&multi_codec1>; }; };
    		      port@1 { ... };
    	};
    };
multi-cpu {
    	compatible = "audio-graph-card2-multi";
/* Front End */
    	ports@0 {
    		port { multi_codec1: endpoint { remote-endpoint = <&cpu1_0>; }; };
    	};
/* Back End */
    	ports@1 {
    		port@0 { multi_codec1_1: endpoint { remote-endpoint = <&codec1_1>; }; };
    		port@1 { multi_codec1_2: endpoint { remote-endpoint = <&codec1_2>; }; };
    		port@2 { multi_codec1_3: endpoint { remote-endpoint = <&codec1_3>; }; };
    	};
    };
codec-device {
    	ports {
    		port@0 { codec1_1: endpoint { remote-endpoint = <&multi_codec1_1>; }; };
    		port@0 { codec1_2: endpoint { remote-endpoint = <&multi_codec1_2>; }; };
    		port@0 { codec1_3: endpoint { remote-endpoint = <&multi_codec1_3>; }; };
    		port@1 { ... };
    	};
    };
Thank you for your help !!
Best regards
---
Kuninori Morimoto