Re: [PATCH v2 0/6] ASoC: extra format on each DAI

[Stephen Gordon <gordoste@xxxxxxxxxxxx>]

On 27/12/2024 11:21 pm, Stephen Gordon wrote:
> On 23/12/2024 1:01 pm, Kuninori Morimoto wrote:
> > > [   27.333830] asoc-audio-graph-card2 soc@107c000000:sound: probe with
> > > driver asoc-audio-graph-card2 failed with error -12

> However, when graph_get_next_multi_ep() is called to get the next 
> endpoint, it returns null. 

Hello Morimoto-san.

I reproduced this using the test components with the attached DTS.

I found that this is because the sibling field of the 
/soc@107c000000/sound/multi/ports@0/port@0 node is null, which means 
that of_graph_get_next_child returns null.

In turn, this is because the linked list of siblings is actually in 
reverse order due to the way populate_node() (drivers/of/fdt.c) adds 
them. This means that when the driver uses remote-endpoint to navigate 
from the endpoint in the cpu node to the endpoint in the multi node, it 
is actually arriving at the last child (with address 0). When calling 
next_child(), it gets null.

[   30.196250] asoc-audio-graph-card2 soc@107c000000:sound: ports 
parent:/soc@107c000000/sound/multi 
child:/soc@107c000000/sound/multi/ports@0/port@2
[   30.196256] asoc-audio-graph-card2 soc@107c000000:sound: sib #0: 
/soc@107c000000/sound/multi/ports@0/port@2
[   30.196260] asoc-audio-graph-card2 soc@107c000000:sound: sib #1: 
/soc@107c000000/sound/multi/ports@0/port@1
[   30.196264] asoc-audio-graph-card2 soc@107c000000:sound: sib #2: 
/soc@107c000000/sound/multi/ports@0/port@0

After finding this, I reversed the order of the port nodes inside 
multi/ports (i.e. the cpu link is now last) and the overlay loads 
without errors.

I get a playback DAI visible in aplay, however the capture DAI is not 
visible in arecord. If I swap the order of the codec ports in 
multi/ports, then I get a capture DAI visible in arecord, but the 
playback DAI is missing :)

I will keep experimenting to see if I can find a way to make them both 
work, but I think some changes are needed to ensure all of the nodes get 
processed.


Regards
Stephen



//Device tree overlay for multi-channel I2S in clock consumer mode
/dts-v1/;
/plugin/;

/ {
    // Pi5 only
    compatible = "brcm,bcm2712";

    fragment@2 {
        target = <&sound>;
        __overlay__ {
	    compatible = "audio-graph-card2";
            label = "ezsound";
            status = "okay";

            links = <&link0>;
            
            multi {
                #address-cells = <1>;
                #size-cells = <0>;
		/*
		 *			+---+
		 *   cpu_i2s <-@------->|X A|-> codec_dac
		 *			|  B|-> codec_adc
		 *			+---+
		 */
		ports@0 {
			reg = <0>;
			#address-cells = <1>;
			#size-cells = <0>;
			port@0 { reg = <0>; link_cpu: endpoint { remote-endpoint = <&cpu_i2s>;    };};
			port@1 { reg = <1>; link_dac: endpoint { remote-endpoint = <&codec_dac>;  };};
			port@2 { reg = <2>; link_adc: endpoint { remote-endpoint = <&codec_adc>;  };};
                };
            };
        };
    };

    // Bring the I2S clock consumer block up
    fragment@4 {
        target-path = "/";
        __overlay__ {
            test-cpu {
                compatible = "test-cpu-verbose";
                #sound-dai-cells = <0>;
                status = "okay";
	        ports {
                    #address-cells = <1>;
                    #size-cells = <0>;
		    link0: port@0 {
                        reg = <0>;
                        cpu_i2s: endpoint {
                            dai-tdm-slot-num = <2>;
                            dai-tdm-slot-width = <32>;
                            remote-endpoint = <&link_cpu>;
                        };
                    };
                };
            };
        };
    };

    fragment@5 {
        target-path = "/";
        __overlay__ {
            test-codec {
                compatible = "test-codec-verbose";
                #sound-dai-cells = <1>;
                status = "okay";
		ports {
			#address-cells = <1>;
			#size-cells = <0>;
                        prefix = "pcm3168a";

			port@0 {
                            reg = <0>;
                            codec_dac: endpoint {
                                playback-only;
                                dai-tdm-slot-num = <2>;
                                dai-tdm-slot-width = <32>;
                                remote-endpoint = <&link_dac>;
                            };
                        };
			port@1 {
                            reg = <1>;
                            codec_adc: endpoint {
                                bitclock-master;
                                frame-master;
                                capture-only;
                                dai-tdm-slot-num = <2>;
                                dai-tdm-slot-width = <32>;
                                remote-endpoint = <&link_adc>;
                            };
                        };
                };
            };
        };
    };
};