linux-kernel - Re: [alsa-devel] [PATCH 4/4] ASoC: da7213: Improve 32KHz mode PLL locking

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Date:	Fri, 5 Aug 2016 11:04:51 +0200 (CEST)
From:	Peter Meerwald-Stadler <pmeerw@...erw.net>
To:	Adam Thomson <Adam.Thomson.Opensource@...semi.com>
cc:	Mark Brown <broonie@...nel.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
	Support Opensource <support.opensource@...semi.com>,
	linux-kernel@...r.kernel.org, c.huber@...-electronic.com
Subject: Re: [alsa-devel] [PATCH 4/4] ASoC: da7213: Improve 32KHz mode PLL
 locking


> To aid PLL in locking on to a 32KHz MCLK, some register mods
> are made during PLL configuration, and when enabling the DAI,
> to achieve the full range of sample rates.

thanks for the patch series; we are about to test...

some comments below
 
> Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@...semi.com>
> ---
>  sound/soc/codecs/da7213.c | 25 ++++++++++++++++++++++++-
>  1 file changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/sound/soc/codecs/da7213.c b/sound/soc/codecs/da7213.c
> index 79b8324..095fe40 100644
> --- a/sound/soc/codecs/da7213.c
> +++ b/sound/soc/codecs/da7213.c
> @@ -750,11 +750,18 @@ static int da7213_dai_event(struct snd_soc_dapm_widget *w,
>  		snd_soc_update_bits(codec, DA7213_PC_COUNT,
>  				    DA7213_PC_FREERUN_MASK, 0);
> 
> -		/* Slave mode, if SRM not enabled no need for status checks */
> +		/* If SRM not enabled then nothing more to do */
>  		pll_ctrl = snd_soc_read(codec, DA7213_PLL_CTRL);
>  		if (!(pll_ctrl & DA7213_PLL_SRM_EN))
>  			return 0;
> 
> +		/* Assist 32KHz mode PLL lock */
> +		if (pll_ctrl & DA7213_PLL_32K_MODE) {

these registers cannot not found in the datasheet;
maybe add descriptive #defines in da7213.h

> +			snd_soc_write(codec, 0xF0, 0x8B);
> +			snd_soc_write(codec, 0xF2, 0x03);
> +			snd_soc_write(codec, 0xF0, 0x00);
> +		}
> +
>  		/* Check SRM has locked */
>  		do {
>  			pll_status = snd_soc_read(codec, DA7213_PLL_STATUS);
> @@ -771,6 +778,14 @@ static int da7213_dai_event(struct snd_soc_dapm_widget *w,
> 
>  		return 0;
>  	case SND_SOC_DAPM_POST_PMD:
> +		/* Revert 32KHz PLL lock udpates if applied previously */
> +		pll_ctrl = snd_soc_read(codec, DA7213_PLL_CTRL);
> +		if (pll_ctrl & DA7213_PLL_32K_MODE) {
> +			snd_soc_write(codec, 0xF0, 0x8B);
> +			snd_soc_write(codec, 0xF2, 0x01);
> +			snd_soc_write(codec, 0xF0, 0x00);
> +		}
> +
>  		/* PC free-running */
>  		snd_soc_update_bits(codec, DA7213_PC_COUNT,
>  				    DA7213_PC_FREERUN_MASK,
> @@ -1428,6 +1443,14 @@ static int da7213_set_dai_pll(struct snd_soc_dai *codec_dai, int pll_id,
>  			    DA7213_PLL_INDIV_MASK | DA7213_PLL_MODE_MASK,
>  			    pll_ctrl);
> 
> +	/* Assist 32KHz mode PLL lock */
> +	if (source == DA7213_SYSCLK_PLL_32KHZ) {
> +		snd_soc_write(codec, 0xF0, 0x8B);
> +		snd_soc_write(codec, 0xF1, 0x03);
> +		snd_soc_write(codec, 0xF1, 0x01);
> +		snd_soc_write(codec, 0xF0, 0x00);
> +	}
> +
>  	return 0;
>  }

-- 

Peter Meerwald-Stadler
+43-664-2444418 (mobile)