Hi device-tree and sound Maintainers,
I have a question regarding multi-lane i2S representation.
On the Allwinner SoC the I2S/PCM Interface can handle up to four lanes as output or input. For each lane we can enable up to sixteen slots. And for each output slot we can choose which slot to map.
The only representation I found is for Amlogic device-tree they did the following sound node : /* 8ch hdmi interface */ dai-link-7 { sound-dai = <&tdmif_b>; dai-format = "i2s"; dai-tdm-slot-tx-mask-0 = <1 1>; dai-tdm-slot-tx-mask-1 = <1 1>; dai-tdm-slot-tx-mask-2 = <1 1>; dai-tdm-slot-tx-mask-3 = <1 1>; mclk-fs = <256>;
codec { sound-dai = <&tohdmitx TOHDMITX_I2S_IN_B>; }; };
This kind of representation gives the information that 2 slots should be enabled as TX per lane but don't give which slot to map. I was thinking about a representation per lane but maybe it's a bit complicated ?
dai-format = "dsp_a"; dai-tdm-slot-width = <32>; // Lane 0 : Output 8 channels 0-7 using TDM dai-tdm-slot-tx-mask-0 = <1 1 1 1 1 1 1 1>; dai-tdm-slot-chmap-0 = <0 1 2 3 4 5 6 7>; // Lane 1 : Output 3 channels 5-7 using TDM dai-tdm-slot-tx-mask-1 = <1 1 1>; dai-tdm-slot-chmap-1 = <5 6 7>;
I will only start to support HDMI, so 4 I2S lanes for now it should look like this
dai-format = "i2s"; dai-tdm-slot-width = <32>; frame-inversion; // Lane 0 : Output channels 0,1 dai-tdm-slot-tx-mask-0 = <1 1>; dai-tdm-slot-chmap-0 = <0 1>; // Lane 1: Output channels 2,3 dai-tdm-slot-tx-mask-1 = <1 1>; dai-tdm-slot-chmap-1 = <2 3>; // Lane 2: Output channels 4,5 dai-tdm-slot-tx-mask-2 = <1 1>; dai-tdm-slot-chmap-2 = <4 5>; // Lane 3: Output channels 6,7 dai-tdm-slot-tx-mask-3 = <1 1>; dai-tdm-slot-chmap-3 = <6 7>;
What do you think? Do you have any remark / idea about this ?
Thanks for your help Clement