[alsa-devel] simple card, asymetrical configuration

[Kuninori Morimoto]

Hi Michael

> sound {
> 	compatible = "simple-audio-card";
> 	simple-audio-card,format = "i2s";
> [snip]
> 	simple-audio-card,bitclock-master = <&dailink0_master>;
> 	simple-audio-card,frame-master = <&dailink0_master>;
> 
> 	simple-audio-card,cpu at 0 {
> 		sound-dai = <&sai6>;
> 	};
> 
> 	simple-audio-card,cpu at 1 {
> 		sound-dai = <&sai5>;
> 	};
> 
> 	dailink0_master: simple-audio-card,codec {
> 		sound-dai = <&wm8904>;
> 	};
> };
> 
> Just for the background, I have hardware with the LS1028A which only
> have unidirectional SAIs. But two of those SAIs (one for playback and
> one for capture) are connected to one codec (with a shared bit and
> frame clock).
> 
> So I thought the example in the simple-card bindings makes sense for
> my case. Although I don't really know what "(Mixing)" means.
> 
> Nevertheless, using the fragment above, the kernel oopses or fails to
> probe the hardware. I've traced that back to the following:
>  - the count is correct: the kernel reports "link 2, dais 3, ccnf
> 0". please note the 3 dais here.
>  - but simple_dai_link_of() will always "allocate" two dais from the
> pool:
> 
>         cpu_dai                 =
>         dai_props->cpu_dai      = &priv->dais[li->dais++];
>         codec_dai               =
>         dai_props->codec_dai    = &priv->dais[li->dais++];
> 
> While this still works for the first link, the second one will fail
> because codec_dai will not be valid.
> 
> Btw, converting that to two explicit dai-link nodes, the dai count
> will be 4 and it will work.
> 
> Is my use case correct or should I use the two explicit dai-link
> nodes? But in any case there seems to be a bug in simple-card.

I guess you want to use "simple-scu-audio-card"
instead of "simple-audio-card" in this case ?

	sound {
-		compatible = "simple-audio-card";
+		compatible = "simple-scu-audio-card";


Thank you for your help !!
Best regards
---
Kuninori Morimoto