[alsa-devel] WM8731 using I2S on omap3 McBSP2 issues

[Peter Ujfalusi]

On Friday 25 September 2009 09:03:06 Ujfalusi Peter (Nokia-D/Tampere) wrote:
> Hello,
> 
> On Thursday 24 September 2009 20:06:07 ext Rick Bronson wrote:
> > Hi,
> >
> >   I'm working on getting a WM8731 (in SLAVE) working using I2S on
> > omap3 McBSP2 (in MASTER).
> >
> >
> > static int omap3csb740_hw_params(struct snd_pcm_substream *substream,
> > ...
> >  ret = snd_soc_dai_set_fmt(codec_dai, SND_SOC_DAIFMT_I2S |
> >   SND_SOC_DAIFMT_NB_NF |  SND_SOC_DAIFMT_CBS_CFS);
> >  ret = snd_soc_dai_set_fmt(cpu_dai,  SND_SOC_DAIFMT_I2S |
> >   SND_SOC_DAIFMT_NB_NF |  SND_SOC_DAIFMT_CBS_CFS);
> >  ret = snd_soc_dai_set_sysclk(codec_dai, 0, 12288000,  
> > SND_SOC_CLOCK_IN); ret = snd_soc_dai_set_sysclk(cpu_dai,
> > OMAP_MCBSP_SYSCLK_CLKS_EXT, 0, SND_SOC_CLOCK_IN);
> 
> I think the problem is here.
> The MCBSP_CLKS pin is connected to CLK256FS pin of TWL4030 (or TPA).

This applies for the Beagle board, which I thought that you are using that from 
this line:
> 4 beagle:~# aplay test48000.wav

Can you check that the clock is running between
CLKOUT (WM8731) -> McBSP_CLKS (OMAP3) pins?

If the clock is missing, than the functional clock is not running.

> Since you are not using the TWL codec, there will be no clock on the
>  MCBSP_CLKS pin, thus no functional clock for McBSP, thus no bits are
>  shifted in or out. You can try to use the internal functional clock:
> 
>   ret = snd_soc_dai_set_sysclk(cpu_dai, OMAP_MCBSP_SYSCLK_CLKS_FCLK, 0,
>     SND_SOC_CLOCK_IN);
> 
> Than set the correct divider, which depends on the frequency you would like
>  to play. The source for the CLKS_FCLK is (in case of McBSP2) PER_96M_FCLK,
>  so 96MHz. Now you have to divide this to get the correct value, as I
>  recall quite a long time ago there were some discussion about this here,
>  and I have sent some 'formula' to calculate it, but I can not find it now
>  :(
> 
> >  ret = snd_soc_dai_set_clkdiv(cpu_dai, OMAP_MCBSP_CLKGDV, 256);
> >
> >   Any help is greatly appreciated.
> >
> >   Rick Bronson
> 

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