Re: [alsa-devel] Question about OF-graph ports

20 Jan 2017


      Hi Rob
Thank you for your feedback
...
...
    SoC.0              Codec0
    SoC.1 <-> Card <-> Codec1
    SoC.2              Codec2

(snip)
...
The card should only have the entry (or exit) points of the graph.
That may not even need to be graph nodes. It could just be a list of
CPU DAI phandles (which then have graph nodes).
Look at the display side use of OF graph. We have display subsystem
nodes (like a card) with a poorly named ports property (nothing to do
with OF graph) listing display channels. Each phandle there is the
entry point to the graph and is typically the front end display
controller (perhaps a CSC and scaling unit). The graph then goes to a
backend controller (for display timing), then to interface PHY
(DSI/HDMI), then possibly and external bridge chip, then to a
connector or panel node. That's a complex example. In simple cases, we
just have a display controller connected to a panel.
If my understanding here was correct, do you mean like this ?
sound_dai0 {
    	ports {
    		port { /* Card.0  */ }
    		port { /* SoC.0  */ }
    		port { /* Codec0 */ }
    	};
    };
sound_dai1 {
    	ports {
    		port { /* Card.1  */ }
    		port { /* SoC.1  */ }
    		port { /* Codec1 */ }
    	};
    };
sound_dai2 {
    	ports {
    		port { /* Card.2  */ }
    		port { /* SoC.2  */ }
    		port { /* Codec2 */ }
    	};
    };
card {
    	ports {
    		port { /* sound_dai0 */ }
    		port { /* sound_dai1 */ }
    		port { /* sound_dai2 */ }
    	};
    };
Or this ?
sound_dai0 {
    	ports {
    		port { /* SoC.0  */ }
    		port { /* Codec0 */ }
    	};
    };
sound_dai1 {
    	ports {
    		port { /* SoC.1  */ }
    		port { /* Codec1 */ }
    	};
    };
sound_dai2 {
    	ports {
    		port { /* SoC.2  */ }
    		port { /* Codec2 */ }
    	};
    };
card {
    	dais = <&sound_dai0
    		&sound_dai1
    		&sound_dai2>;
    };
Best regards
---
Kuninori Morimoto