[alsa-devel] simple card, asymetrical configuration

[alsa-devel] simple card, asymetrical configuration

[Michael Walle]

Hi Kuninori,

there seems to be a problem in the simple-card using the following 
device tree fragment:

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@0 {
		sound-dai = <&sai6>;
	};

	simple-audio-card,cpu@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.

-michael
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Re: [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@0 {
> 		sound-dai = <&sai6>;
> 	};
> 
> 	simple-audio-card,cpu@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
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Re: [alsa-devel] simple card, asymetrical configuration

[Michael Walle]

Hi Kuninori,

Am 2019-12-03 01:54, schrieb 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@0 {
>> 		sound-dai = <&sai6>;
>> 	};
>> 
>> 	simple-audio-card,cpu@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";

Thanks, I'll try that tomorrow.

But nevertheless, shouldn't there be a check for a misconfiguration? At 
least the bindings document should mention that this configuration is 
only valid for for the "scu" case. Oh and I've just had a look, the 
compatible string of this configuration is "simple-audio-card" in 
Documentation/devicetree/bindings/sound/simple-card.txt.

-michael
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Re: [alsa-devel] simple card, asymetrical configuration

[Kuninori Morimoto]

Hi Michael

> But nevertheless, shouldn't there be a check for a misconfiguration?

Yeah, maybe.

> At least the bindings document should mention that this configuration
> is only valid for for the "scu" case. Oh and I've just had a look, the
> compatible string of this configuration is "simple-audio-card" in
> Documentation/devicetree/bindings/sound/simple-card.txt.

Between ourselves, historically, "scu" user was only me, and was used locally.
At one point, "simple-audio-card" had been handled both, but noticed that
it is impossible or will be super very complex.
Because I was the only user of "scu", it is separated.

"scu" is for DPCM, but is covering only one part.
It is not enough for generic use case...

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