[Orange Pi 5 Plus] I2S output with 40 pin GPIO header on 24.10 builds (mainline-6.11 oracular)

[arun-511]

RK3588 has total 4 i2s interfaces (i2s0/i2s1 with 8 channels and i2s2/i2s3 with 2 channels).

Orange Pi 5 Plus GPIO Pinout diagrams on the internet don't have any specific clue if any of these i2s interfaces are exposed via the 40 pin GPIO header.

However the Orange Pi 5 Plus schematics on the official downloads has something interesting

The Pins 40, 38, 35, 31, 12 seems to have some PCM functionalities.

Further diving into the dts files in the oracular branch

from rk3588-base-pinctrl.dtsi we conform that these are indeed i2s3 pins.

again in rk3588-base.dtsi the i2s3_2c interface is already there with proper pins assigned.

So with my zero knowledge with dts, after a lot of trial and errors, I made this overlay to add a pcm5102 node, for simple i2s output.

/dts-v1/;
/plugin/;

/ {
	compatible = "xunlong,orangepi-5-plus", "rockchip,rk3588";

	/* Simple I2S output can be used with with PCM5102a DAC */
	fragment@0 {
		target-path = "/";

		__overlay__ {
			pcm5102 {
				compatible = "simple-audio-card";

				status = "okay";

				simple-audio-card,name = "PCM5102";
				simple-audio-card,format = "i2s";
				simple-audio-card,bitclock-master = <&pcm5102_cpu>;
				simple-audio-card,frame-master = <&pcm5102_cpu>;

				simple-audio-card,widgets =
							"Headphone", "Headphone",
							"Speaker", "Speaker",
							"Microphone", "Microphone";

				pcm5102_cpu: simple-audio-card,cpu {
					sound-dai = <&i2s3_2ch>;
					/* system-clock-frequency = <12288000>; */
				};

				pcm5102_codec: simple-audio-card,codec {
					sound-dai = <&pcm5102_master>;
					/* system-clock-frequency = <12288000>; */
				};
			};

			/* Simple Codec PCM5102a doesn't have a I2C control interface */
			pcm5102_master: pcm5102a {
				#sound-dai-cells = <0>;
				compatible = "ti,pcm5102a";
			};
		};
	};
};

compile it with device-tree-compiler

dtc -@ -I dts -O dtb i2s3-overlay.dts -o i2s3-overlay.dtbo

copy the .dtbo to the path /lib/firmware/$(uname -r)/device-tree/rockchip/overlay (create the path if not exists) and then edit the /etc/default/u-boot like this.

## /etc/default/u-boot - configuration file for u-boot-update(8)

#U_BOOT_UPDATE="true"

#U_BOOT_ALTERNATIVES="default recovery"
#U_BOOT_DEFAULT="l0"
#U_BOOT_PROMPT="1"
#U_BOOT_ENTRIES="all"
#U_BOOT_MENU_LABEL="Debian GNU/Linux"
#U_BOOT_PARAMETERS="ro earlycon"
#U_BOOT_ROOT=""
#U_BOOT_TIMEOUT="50"
#U_BOOT_FDT=""
#U_BOOT_FDT_DIR="/lib/firmware/"
U_BOOT_FDT_OVERLAYS="device-tree/rockchip/overlay/i2s3-overlay.dtbo"
#U_BOOT_FDT_OVERLAYS_DIR="/lib/firmware/"
#U_BOOT_SYNC_DTBS="false"

Tip
don't forget to run sudo u-boot-update after saving the u-boot.

Result appear as alsa_output.platform-pcm5102.stereo-fallback and Built-in Audio Stereo alongside the onboard es8328 that doesn't seem to work for on the mainline builds.

With the same procedure I am able to add I2C, SPI, PWM overlays as well, which are missing from the mainline but still has every thing defined in the rk3588-base.dtsi & rk3588-base-pinctrl.dtsi.

I have been looking for i2s on Orange Pi 5 Plus for more than a year. There is very little documentation on this topic, I hope this would help someone out.