Re: [PATCH] Subject: ASoC stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J

Re: [PATCH] Subject: ASoC stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J

[Mark Brown]

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On Fri, Apr 03, 2026 at 02:07:52PM +0000, Tomasz Merta wrote:
> From 553c09cfa84fa801fbd8dcd5c9ae96e94a54ee31 Mon Sep 17 00:00:00 2001
> 
> Tomasz Merta
> Software Engineer
> E: Tomasz.Merta@arrow.com
> Arrow Electronics | arrow.com
> From: Tomasz Merta <tomasz.merta@arrow.com>
> Date: Fri, 3 Apr 2026 10:33:11 +0200
> Subject: [PATCH] Subject: 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.

Your mail is pretty mangled here, there's a HTML part and the patch
appears to be appended after a signature, it looks like all the tabs got
converted into spaces too.  If you're having trouble sending b4's web
submission API:

   https://b4.docs.kernel.org/en/latest/contributor/send.html

bypasses your mail infrastructure which tends to make life easier.

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Re: [PATCH] Subject: ASoC stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J

[Mark Brown]

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On Tue, Apr 07, 2026 at 08:06:01AM +0000, Tomasz Merta wrote:
> From 553c09cfa84fa801fbd8dcd5c9ae96e94a54ee31 Mon Sep 17 00:00:00 2001
> 
> Tomasz Merta
> Software Engineer
> E: Tomasz.Merta@arrow.com
> Arrow Electronics | arrow.com
> From: Tomasz Merta <tomasz.merta@arrow.com>
> Date: Fri, 3 Apr 2026 10:33:11 +0200
> Subject: [PATCH] Subject: ASoC stm32_sai: fix incorrect BCLK polarity for
> DSP_A/B, LEFT_J

It looks like the tab/space thing might've been fixed but this is still
very mangled...

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[PATCH] Subject: ASoC stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J

[Tomasz Merta]

From: Tomasz Merta <tomasz.merta@arrow.com>

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>
---
 sound/soc/stm/stm32_sai_sub.c | 3 +++
 1 file changed, 3 insertions(+)

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:
-- 
2.34.1

Re: [PATCH] Subject: ASoC stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J

[Mark Brown]

On Wed, 08 Apr 2026 10:40:56 +0200, Tomasz Merta wrote:
> Subject: ASoC stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-7.0

Thanks!

[1/1] Subject: ASoC stm32_sai: fix incorrect BCLK polarity for DSP_A/B, LEFT_J
      https://git.kernel.org/broonie/sound/c/0669631dbccd

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