One idea is to confirm that your I2S LR clock and bit clock line is wired in as expected, then set the “rockchip,clk-trcm” appropriately in the device tree.
Check out my setup for the dummy soundcard (this repo branch) which uses the rock3a (i2s bus 3).
It uses the rock3a as bus master - so that would have to change.
It sets up the dts like so (in this patch) :
+ sound {
+ status = "okay";
+ compatible = "simple-audio-card";
+ simple-audio-card,name = "test";
+ simple-audio-card,format="i2s";
+
+ simple-audio-card,bitclock-master = <&cpu_dai>;
+ simple-audio-card,frame-master = <&cpu_dai>;
+ simple-audio-card,mclk-fs = <256>;
+
+ cpu_dai: simple-audio-card,cpu {
+ sound-dai = <&i2s3_2ch>;
+ };
+
+ codec_dai: simple-audio-card,codec {
+ sound-dai = <&i2s3_out>;
+ };
+
+ };
+
+ i2s3_out: i2s3-out {
+ #sound-dai-cells = <0>;
+ compatible = "flatmax,bare";
+ status = "okay";
+ };
+
+
+ i2s3_2ch {
+ status = "okay";
+ };
+