Hi Geert
It is used on "Simple Audio Card". We need <0> if the board is using SSI x 1, and need <1> if the board is using SSI x N. It is not mandatory if the board is using "Audio Graph Card/Card2".
So #sound-dai-cells should be in the board DTS, and never in the SoC .dtsi? Hence it should be moved out of arch/arm/boot/dts/{r8a7740,sh73a0}.dtsi and arch/arm64/boot/dts/renesas/r9a07g0{43,44,54}.dtsi?
Hmm, it is difficult to explain via text...
On rsnd case, how many DAIs exist is based on the board, and its connection (= R-Car SoC). But FSI has fixed DAIs (= SH), thus having #sound-dai-cells on SoC is not strange (= r8a7740/sh73a0).
And I'm not sure how it works on r9a07g0xx, it is not my drivers.
Thank you for your help !!
Best regards --- Kuninori Morimoto