[PATCH] ASoC: fsl_sai: Fix spurious BCLK on resume by clearing BYP

[Chancel Liu <chancel.liu@oss.nxp.com>]

From: Chancel Liu <chancel.liu@nxp.com>

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 <chancel.liu@nxp.com>
---
 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