diff options
| author | Tomasz Merta <tomasz.merta@arrow.com> | 2026-04-08 10:40:56 +0200 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2026-04-08 13:24:21 +0100 |
| commit | 0669631dbccd41cf3ca7aa70213fcd8bb41c4b38 (patch) | |
| tree | b93d9b9f30c06594c9a74fbcc1e45f08305626d5 | |
| parent | 0f71866057262d669ed6a21246eaac0ad6d04d4e (diff) | |
ASoC: stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J
The STM32 SAI driver do not set the clock strobing bit (CKSTR) for DSP_A,
DSP_B and LEFT_J formats, causing data to be sampled on the wrong BCLK
edge when SND_SOC_DAIFMT_NB_NF is used.
Per ALSA convention, NB_NF requires sampling on the rising BCLK edge.
The STM32MP25 SAI reference manual states that CKSTR=1 is required for
signals received by the SAI to be sampled on the SCK rising edge.
Without setting CKSTR=1, the SAI samples on the falling edge, violating
the NB_NF convention. For comparison, the NXP FSL SAI driver correctly
sets FSL_SAI_CR2_BCP for DSP_A, DSP_B and LEFT_J, consistent with its
I2S handling.
This patch adds SAI_XCR1_CKSTR for DSP_A, DSP_B and LEFT_J in
stm32_sai_set_dai_fmt which was verified empirically with a cs47l35 codec.
RIGHT_J (LSB) is not investigated and addressed by this patch.
Note: the STM32 I2S driver (stm32_i2s_set_dai_fmt) may have the same issue
for DSP_A mode, as I2S_CGFR_CKPOL is not set. This has not been verified
and is left for a separate investigation.
Signed-off-by: Tomasz Merta <tommerta@gmail.com>
Link: https://patch.msgid.link/20260408084056.20588-1-tommerta@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
| -rw-r--r-- | sound/soc/stm/stm32_sai_sub.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/sound/soc/stm/stm32_sai_sub.c b/sound/soc/stm/stm32_sai_sub.c index 450e1585edee..3e82fa90e719 100644 --- a/sound/soc/stm/stm32_sai_sub.c +++ b/sound/soc/stm/stm32_sai_sub.c @@ -802,6 +802,7 @@ static int stm32_sai_set_dai_fmt(struct snd_soc_dai *cpu_dai, unsigned int fmt) break; /* Left justified */ case SND_SOC_DAIFMT_MSB: + cr1 |= SAI_XCR1_CKSTR; frcr |= SAI_XFRCR_FSPOL | SAI_XFRCR_FSDEF; break; /* Right justified */ @@ -809,9 +810,11 @@ static int stm32_sai_set_dai_fmt(struct snd_soc_dai *cpu_dai, unsigned int fmt) frcr |= SAI_XFRCR_FSPOL | SAI_XFRCR_FSDEF; break; case SND_SOC_DAIFMT_DSP_A: + cr1 |= SAI_XCR1_CKSTR; frcr |= SAI_XFRCR_FSPOL | SAI_XFRCR_FSOFF; break; case SND_SOC_DAIFMT_DSP_B: + cr1 |= SAI_XCR1_CKSTR; frcr |= SAI_XFRCR_FSPOL; break; default: |