[PATCH] ASoC: fsl_sai: Fix sync error in consumer mode

[PATCH] ASoC: fsl_sai: Fix sync error in consumer mode

[Maarten Zanders]

When configured for default synchronisation (Rx syncs to Tx) and the
SAI operates in consumer mode (clocks provided externally to Tx), a
synchronisation error occurs on Tx on the first attempt after device
initialisation when the playback stream is started while a capture
stream is already active. This results in channel shift/swap on the
playback stream.
Subsequent streams (ie after that first failing one) always work
correctly, no matter the order, with or without the other stream active.

This issue was observed (and fix tested) on an i.MX6UL board connected
to an ADAU1761 codec, where the codec provides both frame and bit clock
(connected to TX pins).

To fix this, always initialize the 'other' xCR4 and xCR5 registers when
we're starting a stream which is synced to the opposite one, irregardless
of the producer/consumer status.

Fixes: 51659ca069ce ("ASoC: fsl-sai: set xCR4/xCR5/xMR for SAI master mode")

Signed-off-by: Maarten Zanders <maarten@zanders.be>
---
 sound/soc/fsl/fsl_sai.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 757e7868e322..178a6e8fbe2c 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -653,12 +653,12 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 		val_cr4 |= FSL_SAI_CR4_CHMOD;
 
 	/*
-	 * For SAI provider mode, when Tx(Rx) sync with Rx(Tx) clock, Rx(Tx) will
-	 * generate bclk and frame clock for Tx(Rx), we should set RCR4(TCR4),
-	 * RCR5(TCR5) for playback(capture), or there will be sync error.
+	 * When Tx(Rx) sync with Rx(Tx) clock, Rx(Tx) will provide bclk and
+	 * frame clock for Tx(Rx). We should set RCR4(TCR4), RCR5(TCR5)
+	 * for playback(capture), or there will be sync error.
 	 */
 
-	if (!sai->is_consumer_mode[tx] && fsl_sai_dir_is_synced(sai, adir)) {
+	if (fsl_sai_dir_is_synced(sai, adir)) {
 		regmap_update_bits(sai->regmap, FSL_SAI_xCR4(!tx, ofs),
 				   FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK |
 				   FSL_SAI_CR4_CHMOD_MASK,
-- 
2.51.0

Re: [PATCH] ASoC: fsl_sai: Fix sync error in consumer mode

[Shengjiu Wang]

On Fri, Oct 24, 2025 at 9:58 PM Maarten Zanders <maarten@zanders.be> wrote:
>
> When configured for default synchronisation (Rx syncs to Tx) and the
> SAI operates in consumer mode (clocks provided externally to Tx), a
> synchronisation error occurs on Tx on the first attempt after device
> initialisation when the playback stream is started while a capture
> stream is already active. This results in channel shift/swap on the
> playback stream.
> Subsequent streams (ie after that first failing one) always work
> correctly, no matter the order, with or without the other stream active.
>
> This issue was observed (and fix tested) on an i.MX6UL board connected
> to an ADAU1761 codec, where the codec provides both frame and bit clock
> (connected to TX pins).
>
> To fix this, always initialize the 'other' xCR4 and xCR5 registers when
> we're starting a stream which is synced to the opposite one, irregardless
> of the producer/consumer status.
>
> Fixes: 51659ca069ce ("ASoC: fsl-sai: set xCR4/xCR5/xMR for SAI master mode")
>
> Signed-off-by: Maarten Zanders <maarten@zanders.be>

Reviewed-by: Shengjiu Wang <shengjiu.wang@gmail.com>

Best regards
Shengjiu wang
> ---
>  sound/soc/fsl/fsl_sai.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> index 757e7868e322..178a6e8fbe2c 100644
> --- a/sound/soc/fsl/fsl_sai.c
> +++ b/sound/soc/fsl/fsl_sai.c
> @@ -653,12 +653,12 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
>                 val_cr4 |= FSL_SAI_CR4_CHMOD;
>
>         /*
> -        * For SAI provider mode, when Tx(Rx) sync with Rx(Tx) clock, Rx(Tx) will
> -        * generate bclk and frame clock for Tx(Rx), we should set RCR4(TCR4),
> -        * RCR5(TCR5) for playback(capture), or there will be sync error.
> +        * When Tx(Rx) sync with Rx(Tx) clock, Rx(Tx) will provide bclk and
> +        * frame clock for Tx(Rx). We should set RCR4(TCR4), RCR5(TCR5)
> +        * for playback(capture), or there will be sync error.
>          */
>
> -       if (!sai->is_consumer_mode[tx] && fsl_sai_dir_is_synced(sai, adir)) {
> +       if (fsl_sai_dir_is_synced(sai, adir)) {
>                 regmap_update_bits(sai->regmap, FSL_SAI_xCR4(!tx, ofs),
>                                    FSL_SAI_CR4_SYWD_MASK | FSL_SAI_CR4_FRSZ_MASK |
>                                    FSL_SAI_CR4_CHMOD_MASK,
> --
> 2.51.0
>

Re: [PATCH] ASoC: fsl_sai: Fix sync error in consumer mode

[Mark Brown]

On Fri, 24 Oct 2025 15:57:15 +0200, Maarten Zanders wrote:
> When configured for default synchronisation (Rx syncs to Tx) and the
> SAI operates in consumer mode (clocks provided externally to Tx), a
> synchronisation error occurs on Tx on the first attempt after device
> initialisation when the playback stream is started while a capture
> stream is already active. This results in channel shift/swap on the
> playback stream.
> Subsequent streams (ie after that first failing one) always work
> correctly, no matter the order, with or without the other stream active.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] ASoC: fsl_sai: Fix sync error in consumer mode
      commit: b2dd1d0d322dce5f331961c927e775b84014d5ab

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark