[alsa-devel] Question about OF-graph ports

19 Jan 2017


      Hi Rob, Mark
and ALSA SoC ML
I'm working for OF-graph base sound card support.
Now I want to know 1 things which can't solve by myself.
It is OF-graph ports
ALSA SoC needs CPU, Codec, and Sound Card.
If CPU <-> Card <-> Codec case, OF-graph will be
card {
    	ports {
    		port@0 {
    			card_in: endpoint {
    				remote-endpoint = <&cpu_out>;
    			};
    		};
    		port@1 {
    			card_out: endpoint {
    				remote-endpoint = <&codec_in>;
    			};
    		};
    	};
    };
cpu {
    	port {
    		cpu_out: endpoint {
    			remote-endpoint = <&card_in>;
    		};
    	};
    };
codec {
    	port {
    		codec_in: endpoint {
    			remote-endpoint = <&card_out>;
    		};
    	};
    };
This is OK.
If CPU has many ports, then ALSA SoC requests 1 Card which has many
DAIs (= Digital Audio Interface).
This case, cpu will have "ports" and many "port", this is OK.
SoC.0              Codec0
    SoC.1 <-> Card <-> Codec1
    SoC.2              Codec2
In "card", CPU/Codec pair is indicated by "ports" now
(= port0 is CPU, port1 is Codec, etc)
My question is in this case, how to know CPU/Codec pair on "card" ?
Can we have *multi ports*, like this ?
card {
    ports {
    	ports@0 {
    		port@0 { /* SoC.0 */ };
    		port@1 { /* Codec0*/ };
    	};
    	ports@1 {
    		port@0 { /* SoC.1 */ };
    		port@1 { /* Codec1*/ };
    	};
    	ports@2 {
    		port@0 { /* SoC.2 */ };
    		port@1 { /* Codec2*/ };
    	};
    };
};
Or can I use grouping, like this ?
card {
    group =	<port@0 port@1>,
    	<port@2 port@3>,
    	<port@4 port@5>;
    ports {
    	port@0 { /* SoC.0 */ };
    	port@1 { /* SoC.1 */ };
    	port@2 { /* SoC.2 */ };
    	port@3 { /* Codec0*/ };
    	port@4 { /* Codec1*/ };
    	port@5 { /* Codec2*/ };
    };
};
Best regards
---
Kuninori Morimoto