Re: [alsa-devel] [PATCH] ASoC: da7219: check SRM lock in trigger callback

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

On 2/10/20 2:16 AM, Brent Lu wrote:
> Intel sst firmware turns on BCLK/WCLK in START Ioctl call which timing is
> later than the DAPM SUPPLY event handler da7219_dai_event is called (in
> PREPARED state). Therefore, the SRM lock check always fail.
> 
> Moving the check to trigger callback could ensure the SRM is locked before
> DSP starts to process data and avoid possisble noise.

This codec is used quite a bit by Chromebooks across multiple 
generations and with both SST and SOF drivers, we need to be careful 
about changes.
I am personally not aware of any issues and never saw an 'SRM failed to 
lock message'. On which platform did you see a problem?

> 
> Signed-off-by: Brent Lu <brent.lu@intel.com>
> ---
>   sound/soc/codecs/da7219.c | 68 +++++++++++++++++++++++++++++++----------------
>   1 file changed, 45 insertions(+), 23 deletions(-)
> 
> diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
> index f83a6ea..0fb5ea5 100644
> --- a/sound/soc/codecs/da7219.c
> +++ b/sound/soc/codecs/da7219.c
> @@ -794,9 +794,7 @@ static int da7219_dai_event(struct snd_soc_dapm_widget *w,
>   	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
>   	struct da7219_priv *da7219 = snd_soc_component_get_drvdata(component);
>   	struct clk *bclk = da7219->dai_clks[DA7219_DAI_BCLK_IDX];
> -	u8 pll_ctrl, pll_status;
> -	int i = 0, ret;
> -	bool srm_lock = false;
> +	int ret;
>   
>   	switch (event) {
>   	case SND_SOC_DAPM_PRE_PMU:
> @@ -820,26 +818,6 @@ static int da7219_dai_event(struct snd_soc_dapm_widget *w,
>   		/* PC synchronised to DAI */
>   		snd_soc_component_update_bits(component, DA7219_PC_COUNT,
>   				    DA7219_PC_FREERUN_MASK, 0);
> -
> -		/* Slave mode, if SRM not enabled no need for status checks */
> -		pll_ctrl = snd_soc_component_read32(component, DA7219_PLL_CTRL);
> -		if ((pll_ctrl & DA7219_PLL_MODE_MASK) != DA7219_PLL_MODE_SRM)
> -			return 0;
> -
> -		/* Check SRM has locked */
> -		do {
> -			pll_status = snd_soc_component_read32(component, DA7219_PLL_SRM_STS);
> -			if (pll_status & DA7219_PLL_SRM_STS_SRM_LOCK) {
> -				srm_lock = true;
> -			} else {
> -				++i;
> -				msleep(50);
> -			}
> -		} while ((i < DA7219_SRM_CHECK_RETRIES) && (!srm_lock));
> -
> -		if (!srm_lock)
> -			dev_warn(component->dev, "SRM failed to lock\n");
> -
>   		return 0;
>   	case SND_SOC_DAPM_POST_PMD:
>   		/* PC free-running */
> @@ -1658,12 +1636,56 @@ static int da7219_hw_params(struct snd_pcm_substream *substream,
>   	return 0;
>   }
>   
> +static int da7219_set_dai_trigger(struct snd_pcm_substream *substream, int cmd,
> +				  struct snd_soc_dai *dai)
> +{
> +	struct snd_soc_component *component = dai->component;
> +	u8 pll_ctrl, pll_status;
> +	int i = 0;
> +	bool srm_lock = false;
> +
> +	switch (cmd) {
> +	case SNDRV_PCM_TRIGGER_START:
> +		/* Slave mode, if SRM not enabled no need for status checks */
> +		pll_ctrl = snd_soc_component_read32(component, DA7219_PLL_CTRL);
> +		if ((pll_ctrl & DA7219_PLL_MODE_MASK) != DA7219_PLL_MODE_SRM)
> +			return 0;
> +
> +		/* Check SRM has locked */
> +		do {
> +			pll_status = snd_soc_component_read32(component,
> +							DA7219_PLL_SRM_STS);
> +			if (pll_status & DA7219_PLL_SRM_STS_SRM_LOCK) {
> +				srm_lock = true;
> +			} else {
> +				++i;
> +				msleep(50);
> +			}
> +		} while ((i < DA7219_SRM_CHECK_RETRIES) && (!srm_lock));
> +
> +		if (!srm_lock)
> +			dev_warn(component->dev, "SRM failed to lock\n");
> +
> +		break;
> +	case SNDRV_PCM_TRIGGER_RESUME:
> +	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
> +	case SNDRV_PCM_TRIGGER_STOP:
> +	case SNDRV_PCM_TRIGGER_SUSPEND:
> +	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
> +	default:
> +		break;
> +	}
> +
> +	return 0;
> +}
> +
>   static const struct snd_soc_dai_ops da7219_dai_ops = {
>   	.hw_params	= da7219_hw_params,
>   	.set_sysclk	= da7219_set_dai_sysclk,
>   	.set_pll	= da7219_set_dai_pll,
>   	.set_fmt	= da7219_set_dai_fmt,
>   	.set_tdm_slot	= da7219_set_dai_tdm_slot,
> +	.trigger	= da7219_set_dai_trigger,
>   };
>   
>   #define DA7219_FORMATS (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S20_3LE |\
>