ASoC: fsl_sai: Constrain sample rates from audio PLLs only in master mode

[PATCH] ASoC: fsl_sai: Constrain sample rates from audio PLLs only in master mode

Posted by Chancel Liu 3 days, 20 hours ago

If SAI works in master mode it will generate clocks for external codec
from audio PLLs. Thus sample rates should be constrained according to
audio PLL clocks. While SAI works in slave mode which means clocks are
generated externally then constraints are independent of audio PLLs.

Fixes: 4edc98598be4 ("ASoC: fsl_sai: Add sample rate constraint")
Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
---
 sound/soc/fsl/fsl_sai.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 72bfc91e21b9..86730c214914 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -917,8 +917,14 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
 					   tx ? sai->dma_params_tx.maxburst :
 					   sai->dma_params_rx.maxburst);
 
-	ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
-					 SNDRV_PCM_HW_PARAM_RATE, &sai->constraint_rates);
+	if (sai->is_consumer_mode[tx])
+		ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
+						 SNDRV_PCM_HW_PARAM_RATE,
+						 &fsl_sai_rate_constraints);
+	else
+		ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
+						 SNDRV_PCM_HW_PARAM_RATE,
+						 &sai->constraint_rates);
 
 	return ret;
 }
-- 
2.50.1

Re: [PATCH] ASoC: fsl_sai: Constrain sample rates from audio PLLs only in master mode

Posted by Shengjiu Wang 2 days, 16 hours ago

On Wed, Dec 10, 2025 at 2:21 PM Chancel Liu <chancel.liu@nxp.com> wrote:
>
> If SAI works in master mode it will generate clocks for external codec
> from audio PLLs. Thus sample rates should be constrained according to
> audio PLL clocks. While SAI works in slave mode which means clocks are
> generated externally then constraints are independent of audio PLLs.
>
> Fixes: 4edc98598be4 ("ASoC: fsl_sai: Add sample rate constraint")
> Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
> ---
>  sound/soc/fsl/fsl_sai.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> index 72bfc91e21b9..86730c214914 100644
> --- a/sound/soc/fsl/fsl_sai.c
> +++ b/sound/soc/fsl/fsl_sai.c
> @@ -917,8 +917,14 @@ static int fsl_sai_startup(struct snd_pcm_substream *substream,
>                                            tx ? sai->dma_params_tx.maxburst :
>                                            sai->dma_params_rx.maxburst);
>
> -       ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
> -                                        SNDRV_PCM_HW_PARAM_RATE, &sai->constraint_rates);
> +       if (sai->is_consumer_mode[tx])

The sai->is_consumer_mode[tx] can be changed after startup(),
then there may be an issue for the constraint.

It looks like there is no perfect solution here.

Best regards
Shengjiu Wang

> +               ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
> +                                                SNDRV_PCM_HW_PARAM_RATE,
> +                                                &fsl_sai_rate_constraints);
> +       else
> +               ret = snd_pcm_hw_constraint_list(substream->runtime, 0,
> +                                                SNDRV_PCM_HW_PARAM_RATE,
> +                                                &sai->constraint_rates);
>
>         return ret;
>  }
> --
> 2.50.1
>