linux-kernel - RE: Problems with simple-card

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Date:	Thu, 16 Jan 2014 03:47:58 +0000
From:	"Li.Xiubo@...escale.com" <Li.Xiubo@...escale.com>
To:	Jean-Francois Moine <moinejf@...e.fr>,
	"broonie@...nel.org" <broonie@...nel.org>,
	Kuninori Morimoto <kuninori.morimoto.gx@...il.com>
CC:	"lgirdwood@...il.com" <lgirdwood@...il.com>,
	"alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: Problems with simple-card

Hi,

> I did a mistake in the v1 of my 'ASoC: simple-card: simplify code': I
> did not initialize the pointer to the asoc_simple_card_dai_init()
> function when DT. Then, I fixed that, and the simple card does not work
> for me.
> 
> First, without any 'format' in the DT, I get a fmt for each CPU / CODEC
> DAI: SND_SOC_DAIFMT_CBS_CFS is always set. Well, some code is executed
> for nothing, but this is not critical.
> 

This is the old issue that I have raised before, which is one limitation
of snd_soc_of_parse_daifmt(). As descript above, if without any fmt in the
DT node, and just using snd_soc_of_parse_daifmt() for each CPU/CODEC DAI fmt
the SND_SOC_DAIFMT_CBS_CFS (none zero) is always set.

@Mark and Morimoto-san, there has two ways to deal with this in my mind:
Fist, in the snd_soc_of_parse_daifmt(), modifying the
boolen : "[prefix]bitclock-master"
boolen : "[prefix]frame-master"
	==> 
[prefix]master = "XXX" and "XXX" is :
"cbm-cfm" --> SND_SOC_DAIFMT_CBM_CFM          
"cbs-cfm" --> SND_SOC_DAIFMT_CBS_CFM          
"cbm-cfs" --> SND_SOC_DAIFMT_CBM_CFS          
"cbs-cfs" --> SND_SOC_DAIFMT_CBS_CFS         

And the default value will be zero...

If this method is applied, and there is no need any masks for
snd_soc_of_parse_daifmt(), like in simple card driver:

/* get CPU/CODEC common format via simple-audio-card,format */
info->daifmt = snd_soc_of_parse_daifmt(node, "simple-audio-card,") &
           (SND_SOC_DAIFMT_FORMAT_MASK | SND_SOC_DAIFMT_INV_MASK);

Second, if there hasn't any DAI fmts in DT node and at the same time the CPU
and CODEC DAI devices don't need to care about of them, and set_dai() pointer
could be set to be NULL, and then snd_soc_dai_set_fmt() just returned -ENOTSUPP.

Thanks,