From: Arun Raghavan <arun@asymptotic.io>

On an imx8mm platform with an external clock provider, when running the
receiver (arecord) and triggering an xrun with xrun_injection, we see a
channel swap/offset. This happens sometimes when running only the
receiver, but occurs reliably if a transmitter (aplay) is also
concurrently running.

It seems that the SAI loses track of frame sync during the trigger stop
-> trigger start cycle that occurs during an xrun. Doing just a FIFO
reset in this case does not suffice, and only a software reset seems to
get it back on track.

This looks like the same h/w bug that is already handled for the
producer case, so we now do the reset unconditionally on config disable.

Signed-off-by: Arun Raghavan <arun@asymptotic.io>
Reported-by: Pieterjan Camerlynck <p.camerlynck@televic.com>
Fixes: 3e3f8bd56955 ("ASoC: fsl_sai: fix no frame clk in master mode")
Cc: stable@vger.kernel.org
---

v4
- Add Fixes and cc stable

v3
- Incorporate feedback from Shengjiu Wang to consolidate with the
  existing handling of this issue in producer mode

v2 (no longer relevant)
- Address build warning from kernel test robot

 sound/soc/fsl/fsl_sai.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index af1a168d35e3..50af6b725670 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -803,13 +803,15 @@ static void fsl_sai_config_disable(struct fsl_sai *sai, int dir)
 	 * anymore. Add software reset to fix this issue.
 	 * This is a hardware bug, and will be fix in the
 	 * next sai version.
+	 *
+	 * In consumer mode, this can happen even after a
+	 * single open/close, especially if both tx and rx
+	 * are running concurrently.
 	 */
-	if (!sai->is_consumer_mode[tx]) {
-		/* Software Reset */
-		regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), FSL_SAI_CSR_SR);
-		/* Clear SR bit to finish the reset */
-		regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), 0);
-	}
+	/* Software Reset */
+	regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), FSL_SAI_CSR_SR);
+	/* Clear SR bit to finish the reset */
+	regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), 0);
 }
 
 static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
-- 
2.49.0

On Thu, 26 Jun 2025 09:08:25 -0400, Arun Raghavan wrote:
> On an imx8mm platform with an external clock provider, when running the
> receiver (arecord) and triggering an xrun with xrun_injection, we see a
> channel swap/offset. This happens sometimes when running only the
> receiver, but occurs reliably if a transmitter (aplay) is also
> concurrently running.
> 
> It seems that the SAI loses track of frame sync during the trigger stop
> -> trigger start cycle that occurs during an xrun. Doing just a FIFO
> reset in this case does not suffice, and only a software reset seems to
> get it back on track.
> 
> [...]

Applied to

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

Thanks!

[1/1] ASoC: fsl_sai: Force a software reset when starting in consumer mode
      commit: dc78f7e59169d3f0e6c3c95d23dc8e55e95741e2

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

On Thu, Jun 26, 2025 at 9:09 PM Arun Raghavan <arun@arunraghavan.net> wrote:
>
> From: Arun Raghavan <arun@asymptotic.io>
>
> On an imx8mm platform with an external clock provider, when running the
> receiver (arecord) and triggering an xrun with xrun_injection, we see a
> channel swap/offset. This happens sometimes when running only the
> receiver, but occurs reliably if a transmitter (aplay) is also
> concurrently running.
>
> It seems that the SAI loses track of frame sync during the trigger stop
> -> trigger start cycle that occurs during an xrun. Doing just a FIFO
> reset in this case does not suffice, and only a software reset seems to
> get it back on track.
>
> This looks like the same h/w bug that is already handled for the
> producer case, so we now do the reset unconditionally on config disable.
>
> Signed-off-by: Arun Raghavan <arun@asymptotic.io>
> Reported-by: Pieterjan Camerlynck <p.camerlynck@televic.com>
> Fixes: 3e3f8bd56955 ("ASoC: fsl_sai: fix no frame clk in master mode")
> Cc: stable@vger.kernel.org

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

Best regards
Shengjiu Wang
> ---
>
> v4
> - Add Fixes and cc stable
>
> v3
> - Incorporate feedback from Shengjiu Wang to consolidate with the
>   existing handling of this issue in producer mode
>
> v2 (no longer relevant)
> - Address build warning from kernel test robot
>
>  sound/soc/fsl/fsl_sai.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
> index af1a168d35e3..50af6b725670 100644
> --- a/sound/soc/fsl/fsl_sai.c
> +++ b/sound/soc/fsl/fsl_sai.c
> @@ -803,13 +803,15 @@ static void fsl_sai_config_disable(struct fsl_sai *sai, int dir)
>          * anymore. Add software reset to fix this issue.
>          * This is a hardware bug, and will be fix in the
>          * next sai version.
> +        *
> +        * In consumer mode, this can happen even after a
> +        * single open/close, especially if both tx and rx
> +        * are running concurrently.
>          */
> -       if (!sai->is_consumer_mode[tx]) {
> -               /* Software Reset */
> -               regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), FSL_SAI_CSR_SR);
> -               /* Clear SR bit to finish the reset */
> -               regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), 0);
> -       }
> +       /* Software Reset */
> +       regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), FSL_SAI_CSR_SR);
> +       /* Clear SR bit to finish the reset */
> +       regmap_write(sai->regmap, FSL_SAI_xCSR(tx, ofs), 0);
>  }
>
>  static int fsl_sai_trigger(struct snd_pcm_substream *substream, int cmd,
> --
> 2.49.0
>

On Thu, Jun 26, 2025 at 10:09 AM Arun Raghavan <arun@arunraghavan.net> wrote:
>
> From: Arun Raghavan <arun@asymptotic.io>
>
> On an imx8mm platform with an external clock provider, when running the
> receiver (arecord) and triggering an xrun with xrun_injection, we see a
> channel swap/offset. This happens sometimes when running only the
> receiver, but occurs reliably if a transmitter (aplay) is also
> concurrently running.
>
> It seems that the SAI loses track of frame sync during the trigger stop
> -> trigger start cycle that occurs during an xrun. Doing just a FIFO
> reset in this case does not suffice, and only a software reset seems to
> get it back on track.
>
> This looks like the same h/w bug that is already handled for the
> producer case, so we now do the reset unconditionally on config disable.
>
> Signed-off-by: Arun Raghavan <arun@asymptotic.io>
> Reported-by: Pieterjan Camerlynck <p.camerlynck@televic.com>
> Fixes: 3e3f8bd56955 ("ASoC: fsl_sai: fix no frame clk in master mode")
> Cc: stable@vger.kernel.org

Reviewed-by: Fabio Estevam <festevam@gmail.com>