Re: [PATCH] ASoC: fsl_sai: Fix spurious BCLK on resume by clearing BYP
From: Shengjiu Wang <shengjiu.wang@gmail.com>
Date: 2026-07-08 06:09:51
Also in:
linux-sound, lkml
On Tue, Jul 7, 2026 at 4:47 PM Chancel Liu [off-list ref] wrote:
From: Chancel Liu <redacted>
When the BCLK divider ratio is 1:1, fsl_sai_set_bclk() enables bypass
mode by setting BYP, but never clears the bit. The BYP=1 value remains
in the regcache, and is restored by regcache_sync() on the next runtime
resume.
Since BYP=1 combined with BCD=1 immediately outputs the ungated MCLK
as BCLK without waiting for BCE/TE/RE to be enabled, the clock is
driven prematurely before the stream is fully configured, causing
noise on some codecs.
Fix this by clearing BYP and BCI together in fsl_sai_config_disable().
Also clear BCI, which is programmed together with the bypass case in
synchronous mode, so the cached CR2 state is clean and regcache_sync()
will not restore bypass mode prematurely on the next resume.
Fixes: a50b7926d015 ("ASoC: fsl_sai: implement 1:1 bclk:mclk ratio support")
Signed-off-by: Chancel Liu <redacted>Reviewed-by: Shengjiu Wang <shengjiu.wang@gmail.com> Best regards Shengjiu Wang
quoted hunk ↗ jump to hunk
--- sound/soc/fsl/fsl_sai.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c index 9661602b53c5..4c0626d572a5 100644 --- a/sound/soc/fsl/fsl_sai.c +++ b/sound/soc/fsl/fsl_sai.c@@ -847,6 +847,9 @@ static void fsl_sai_config_disable(struct fsl_sai *sai, int dir) regmap_update_bits(sai->regmap, FSL_SAI_xCSR(tx, ofs), FSL_SAI_CSR_FR, FSL_SAI_CSR_FR); + regmap_update_bits(sai->regmap, FSL_SAI_xCR2(tx, ofs), + FSL_SAI_CR2_BCI | FSL_SAI_CR2_BYP, 0); + /* * For sai master mode, after several open/close sai, * there will be no frame clock, and can't recover --2.50.1