Re: [PATCH v2] ASoC: pcm3168a: Add option to force clock consumer

[Stephen Gordon <gordoste@xxxxxxxxxxxx>]

>  From "Sound Card" point of view, setup directly Bx_Fx base instead of
> CBx_CFx base is not a big deal. But if we do it, we need to have such
> setting for each DAI, instead of common dai_link.
>
> Now dai_link->dai_fmt is including 4 type of info
>
> 	1. DAI hardware audio formats
> 	2. DAI Clock gating
> 	3. DAI hardware signal polarity
> 	4. DAI hardware clock providers/consumers
>
> I think we want to separate 4 (and maybe 2 too ?) from it to support
> more flexible system ?
>
> Legacy system
> 	dai_link->dai_fmt		// include all 1, 2, 3, 4
>
> New system
> 	dai_link->dai_fmt		// include 1, 2, 3 (or 1, 3)
> 	dai_link->cpus[idx].fmt		// include 4       (or 2, 4)
>
> 	fmt = dai_link->dai_fmt | dai_link->cpus[i].fmt
>
> "flip" has effect to 4 only, so New system has no issue with flipping
> on dai_link->dai_fmt.

Hi Morimoto-san,

This is a great idea. I'd add that #4 could still be in 
dai_link->dai_fmt, but the new field in CPU/codec 
(snd_soc_dai_link_component.fmt) should override the setting (not a 
simple OR). This would preserve backward compatibility (I think). It 
greatly improves support for multiple codecs sharing clock lines, where 
1 codec is the producer and others are consumers. The bit/frame logic in 
simple/graph cards should be able to be changed to handle this properly too.

Without this type of override, the original patch is needed (or the card 
driver needs to write registers directly, which seems bad).

I will wait to hear Mark's opinion.

Stephen