[alsa-devel] [PATCH 1/1] ASoC: TWL4030: Add support Voice DAI

[Peter Ujfalusi]

On Thursday 09 April 2009 16:54:37 ext Joonyoung Shim wrote:
> Add Voice DAI to support the PCM voice interface of the twl4030 codec.
>
> The PCM voice interface can be used with 8-kHz(voice narrowband) or 16-kHz
> (voice wideband) sampling rates, and 16bits, and mono RX and mono TX or
> stereo TX.
>
> If the system master clock is not 26MHz, the voice PCM interface is not
> available.
>
> The PCM voice interface has two modes
> - PCM mode1 : This uses the rising edge of the clock signal
> - PCM mode2 : This uses the falling edge of the clock signal
>
> PCM mode1 and mode2 have a look of DSP_A and DSP_B, so we used DSP_A and
> DSP_B.

Both of the PCM mode1 and mode2 is actually DSP_A, but the FS polarity is 
inverted and also the data is shifted/sampled on the opposite edge of the 
bitclock.

> +static int twl4030_voice_startup(struct snd_pcm_substream *substream,
> +				struct snd_soc_dai *dai)
> +{
> +	struct snd_soc_pcm_runtime *rtd = substream->private_data;
> +	struct snd_soc_device *socdev = rtd->socdev;
> +	struct snd_soc_codec *codec = socdev->card->codec;
> +	u8 infreq;
> +
> +	/* If the system master clock is not 26MHz, the voice PCM interface is
> +	 * not avilable.
> +	 */
> +	infreq = twl4030_read_reg_cache(codec, TWL4030_REG_APLL_CTL)
> +		& TWL4030_APLL_INFREQ;
> +
> +	if (infreq != TWL4030_APLL_INFREQ_26000KHZ)
> +		return -EPERM;

Would it be feasible to add a check here against the CODEC_MODE:OPT_MODE and 
if the codec is not in Option2 mode, than return with error?


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