Subject: Re: [PATCH V2] ASoC: fsl_esai: fix channel swap issue when stream starts

From: Nicolin Chen <[email-masked]>
Date: Mon, 25 Feb 2019 13:14:41 -0800

On Mon, Feb 25, 2019 at 02:48:18AM +0000, S.j. Wang wrote:
> There is very low possibility ( < 0.1% ) that channel swap happened
> in beginning when multi output/input pin is enabled. The issue is
> that hardware can't send data to correct pin in the beginning with
> the normal enable flow.
> 
> This is hardware issue, but there is no errata, the workaround flow
> is that: Each time playback/recording, firstly clear the xSMA/xSMB,
> then enable TE/RE, then enable xSMB and xSMA (xSMB must be enabled
> before xSMA). Which is to use the xSMA as the trigger start register,
> previously the xCR_TE or xCR_RE is the bit for starting.
> 
> Fixes 43d24e76b698 ("ASoC: fsl_esai: Add ESAI CPU DAI driver")
> Cc: <[email-masked]>
> Reviewed-by: Fabio Estevam <[email-masked]>
> Signed-off-by: Shengjiu Wang <[email-masked]>
> ---
> Changes in v2
> - update commit comments.
> 
>  sound/soc/fsl/fsl_esai.c | 32 ++++++++++++++++++++++----------
>  1 file changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/sound/soc/fsl/fsl_esai.c b/sound/soc/fsl/fsl_esai.c
> index afe67c865330..23bd0ad4ac31 100644
> --- a/sound/soc/fsl/fsl_esai.c
> +++ b/sound/soc/fsl/fsl_esai.c
> @@ -54,6 +54,8 @@ struct fsl_esai {
>  	u32 fifo_depth;
>  	u32 slot_width;
>  	u32 slots;
> +	u32 tx_mask;
> +	u32 rx_mask;
>  	u32 hck_rate[2];
>  	u32 sck_rate[2];
>  	bool hck_dir[2];
> @@ -361,21 +363,13 @@ static int fsl_esai_set_dai_tdm_slot(struct snd_soc_dai *dai, u32 tx_mask,
>  	regmap_update_bits(esai_priv->regmap, REG_ESAI_TCCR,
>  			   ESAI_xCCR_xDC_MASK, ESAI_xCCR_xDC(slots));
>  
> -	regmap_update_bits(esai_priv->regmap, REG_ESAI_TSMA,
> -			   ESAI_xSMA_xS_MASK, ESAI_xSMA_xS(tx_mask));
> -	regmap_update_bits(esai_priv->regmap, REG_ESAI_TSMB,
> -			   ESAI_xSMB_xS_MASK, ESAI_xSMB_xS(tx_mask));
> -
>  	regmap_update_bits(esai_priv->regmap, REG_ESAI_RCCR,
>  			   ESAI_xCCR_xDC_MASK, ESAI_xCCR_xDC(slots));
>  
> -	regmap_update_bits(esai_priv->regmap, REG_ESAI_RSMA,
> -			   ESAI_xSMA_xS_MASK, ESAI_xSMA_xS(rx_mask));
> -	regmap_update_bits(esai_priv->regmap, REG_ESAI_RSMB,
> -			   ESAI_xSMB_xS_MASK, ESAI_xSMB_xS(rx_mask));
> -
>  	esai_priv->slot_width = slot_width;
>  	esai_priv->slots = slots;
> +	esai_priv->tx_mask    = tx_mask;
> +	esai_priv->rx_mask    = rx_mask;

The two masks only got values here. If a machine driver doesn't
have a set_dai_tdm_slot() call, they will be remained as 0 and
then will seemly clean those four registers.

Thanks
Nicolin

>  
>  	return 0;
>  }
> @@ -596,6 +590,7 @@ static int fsl_esai_trigger(struct snd_pcm_substream *substream, int cmd,
>  	bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
>  	u8 i, channels = substream->runtime->channels;
>  	u32 pins = DIV_ROUND_UP(channels, esai_priv->slots);
> +	u32 mask;
>  
>  	switch (cmd) {
>  	case SNDRV_PCM_TRIGGER_START:
> @@ -611,12 +606,23 @@ static int fsl_esai_trigger(struct snd_pcm_substream *substream, int cmd,
>  		regmap_update_bits(esai_priv->regmap, REG_ESAI_xCR(tx),
>  				   tx ? ESAI_xCR_TE_MASK : ESAI_xCR_RE_MASK,
>  				   tx ? ESAI_xCR_TE(pins) : ESAI_xCR_RE(pins));
> +		mask = tx ? esai_priv->tx_mask : esai_priv->rx_mask;
> +
> +		regmap_update_bits(esai_priv->regmap, REG_ESAI_xSMB(tx),
> +				   ESAI_xSMB_xS_MASK, ESAI_xSMB_xS(mask));
> +		regmap_update_bits(esai_priv->regmap, REG_ESAI_xSMA(tx),
> +				   ESAI_xSMA_xS_MASK, ESAI_xSMA_xS(mask));
> +
>  		break;
>  	case SNDRV_PCM_TRIGGER_SUSPEND:
>  	case SNDRV_PCM_TRIGGER_STOP:
>  	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
>  		regmap_update_bits(esai_priv->regmap, REG_ESAI_xCR(tx),
>  				   tx ? ESAI_xCR_TE_MASK : ESAI_xCR_RE_MASK, 0);
> +		regmap_update_bits(esai_priv->regmap, REG_ESAI_xSMA(tx),
> +				   ESAI_xSMA_xS_MASK, 0);
> +		regmap_update_bits(esai_priv->regmap, REG_ESAI_xSMB(tx),
> +				   ESAI_xSMB_xS_MASK, 0);
>  
>  		/* Disable and reset FIFO */
>  		regmap_update_bits(esai_priv->regmap, REG_ESAI_xFCR(tx),
> @@ -906,6 +912,12 @@ static int fsl_esai_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	/* Clear the TSMA, TSMB, RSMA, RSMB */
> +	regmap_write(esai_priv->regmap, REG_ESAI_TSMA, 0);
> +	regmap_write(esai_priv->regmap, REG_ESAI_TSMB, 0);
> +	regmap_write(esai_priv->regmap, REG_ESAI_RSMA, 0);
> +	regmap_write(esai_priv->regmap, REG_ESAI_RSMB, 0);
> +
>  	ret = devm_snd_soc_register_component(&pdev->dev, &fsl_esai_component,
>  					      &fsl_esai_dai, 1);
>  	if (ret) {
> -- 
> 1.9.1
>