On Thu, Jun 26, 2025 at 9:09 PM Arun Raghavan <a...@arunraghavan.net> wrote:
>
> From: Arun Raghavan <a...@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 <a...@asymptotic.io>
> Reported-by: Pieterjan Camerlynck <p.camerly...@televic.com>
> Fixes: 3e3f8bd56955 ("ASoC: fsl_sai: fix no frame clk in master mode")
> Cc: sta...@vger.kernel.org
Acked-by: Shengjiu Wang <shengjiu.w...@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
>
