[alsa-devel] [PATCH 0/3] ASoC: DPCM can care FE/BE merged format

[Kuninori Morimoto]

Hi Takashi, Mark

Thank you for your feedback

>>     .dpcm_merged_foramt
>>     .dpcm_merged_rate
>>     .dpcm_merged_chan
>
>Better to have bit flags.
> 
>> Maybe I'm misunderstanding, but if this feature
>> refines above all hw_params, it will conflicts
>> with .be_hw_params_fixup ?
>
>Yeah, there it'll need to clear the flag.

.dpcm_merged_foramt is using bit field, like this

	unsigned int dpcm_merged_foramt:1;

I think we don't need flag control, but should I ?
(many other options are same style in struct snd_soc_dai_link)

> > There are indeed cases where a BE takes incompatible hw configuration,
> > which needs be_hw_params_fixup.  But, in general, the FE's hw_params
> > is just copied to BE.  That is, we assume here blindly that FE's
> > configuration is compatible with BE's.  And, now this assumption isn't
> > true in rcar's case, so we face the issue.
> 
> Well, it's as much that we're assuming there's rewriting going on which
> handles things - in many of these systems everything will be going
> through a DSP which rewrites everything on the way.

I guess we can use .be_hw_params_fixup if it is
"special rewrite" (ex 48kHz -> 44.1kHz, 8ch -> 2ch etc...).
But like this case (= it needs rewrite but normally we assume it)
using general method is useful.

I'm happy to create/send v2 patch, but, it will be "flag" fixup ?