[PATCH v5 0/2] ASoC: codecs: nau8360: Fix DSP routing and deadlock issues

[PATCH v5 0/2] ASoC: codecs: nau8360: Fix DSP routing and deadlock issues

[Neo Chang]

This patch series addresses two issues in the nau8360 codec driver
regarding the DAC mux control:

1. An invalid hardware routing state that occurs when the DSP firmware
   fails to load but the userspace attempts to switch to the DSP path.

2. A pre-existing AB-BA deadlock triggered during concurrent stream
   startups or ALSA mixer updates.

---
Changes in v5:
- Patch 1/2: Changed the return value to -EBUSY in the playback check 
  condition (bias_level > STANDBY). (Reported by Dan Carpenter)
- Rebased onto the latest for-next branch and resolved a merge conflict
  in nau8360_dac_mux_put_enum().

Changes in v4:
- Patch 1/2: Changed the return value to -EBUSY instead of 0 to properly
  reject the invalid request and prevent ALSA state desync.
- Patch 1/2: Used dev_warn_ratelimited() instead of dev_warn().
- Patch 2/2: Added a fix for the AB-BA deadlock in nau8360_dac_mux_put_enum().
  (Reported by Sashiko AI)

Changes in v3:
- Block the DSP path selection if the firmware fails to load to prevent
  invalid routing states.

Changes in v2:
- Use snd_soc_component_update_bits() to prevent register overwriting.
  (Reported by Sashiko AI)
- Fix missing bit shift for default PEQ band. (Reported by Sashiko AI)

Neo Chang (2):
  ASoC: codecs: nau8360: Block DSP path selection when firmware load
    fails
  ASoC: codecs: nau8360: Fix AB-BA deadlock in mux update

 sound/soc/codecs/nau8360.c | 21 ++++++++++++++-------
 sound/soc/codecs/nau8360.h |  6 ++++++
 2 files changed, 20 insertions(+), 7 deletions(-)

-- 
2.25.1

[PATCH v5 1/2] ASoC: codecs: nau8360: Block DSP path selection when firmware load fails

[Neo Chang]

Block the DSP path selection if the firmware fails to load to prevent
invalid routing states.

If the firmware is not ready, nau8360_dac_mux_put_enum() will print
a rate-limited warning and return -EBUSY. This rejects the invalid
userspace request and maintains the original hardware state without
causing audio wrong status.

Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/linux-sound/aqK_oOpMAXVhxkHJ@stanley.mountain/
Suggested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Neo Chang <YLCHANG2@nuvoton.com>
---
 sound/soc/codecs/nau8360.c | 9 +++++++--
 sound/soc/codecs/nau8360.h | 6 ++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/nau8360.c b/sound/soc/codecs/nau8360.c
index 89b8ee80d6c8..f5dee12127cd 100644
--- a/sound/soc/codecs/nau8360.c
+++ b/sound/soc/codecs/nau8360.c
@@ -715,8 +715,13 @@ static int nau8360_dac_mux_put_enum(struct snd_kcontrol *kcontrol,
 	int ret = 0;
 
 	if (snd_soc_dapm_get_bias_level(dapm) > SND_SOC_BIAS_STANDBY) {
-		dev_warn(nau8360->dev, "changing path is not allowed during playback");
-		return ret;
+		dev_warn_ratelimited(nau8360->dev, "changing path is not allowed during playback");
+		return -EBUSY;
+	}
+
+	if (item[0] == NAU8360_DAC_SRC_DSP && !nau8360->load_fw_done) {
+		dev_warn_ratelimited(nau8360->dev, "Cannot enable DSP: Firmware not ready or disabled\n");
+		return -EBUSY;
 	}
 
 	mutex_lock(&nau8360->lock);
diff --git a/sound/soc/codecs/nau8360.h b/sound/soc/codecs/nau8360.h
index cc640ba8c838..71396747c0fa 100644
--- a/sound/soc/codecs/nau8360.h
+++ b/sound/soc/codecs/nau8360.h
@@ -870,6 +870,12 @@ enum {
 	NAU8360_TDM_TXN,
 };
 
+/* DAC Source Path*/
+enum {
+	NAU8360_DAC_SRC_HW1 = 0,
+	NAU8360_DAC_SRC_DSP,
+};
+
 /* PLL Source */
 enum {
 	NAU8360_PLL_MCLK,
-- 
2.25.1

[PATCH v5 2/2] ASoC: codecs: nau8360: Fix AB-BA deadlock in mux update

[Neo Chang]

nau8360_dac_mux_put_enum() acquires nau8360->lock before the DAPM mutex,
causing an AB-BA lock inversion. This deadlocks with concurrent stream
startups or mixer updates, which acquire locks in the reverse order.

Fix this by replacing nau8360->lock with the DAPM mutex to protect
pre-checks, releasing it before calling snd_soc_dapm_put_enum_double().

Reported-by: Sashiko AI <sashiko-bot@kernel.org>
Link: https://sashiko.dev/#/patchset/20260908030342.222655-1-YLCHANG2@nuvoton.com?part=1
Signed-off-by: Neo Chang <YLCHANG2@nuvoton.com>
---
 sound/soc/codecs/nau8360.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/sound/soc/codecs/nau8360.c b/sound/soc/codecs/nau8360.c
index f5dee12127cd..f0942739d7ab 100644
--- a/sound/soc/codecs/nau8360.c
+++ b/sound/soc/codecs/nau8360.c
@@ -689,6 +689,8 @@ static void nau8360_dsp_switch(struct snd_soc_component *component, bool enable)
 	struct regmap *regmap = nau8360->regmap;
 	int value = NAU8360_PEQ_BAND_8;
 
+	mutex_lock(&nau8360->lock);
+
 	/* If DSP is enabled, unstall HW3 engine and DSP, loading DSP firmware,
 	 * and configure PEQ after dsp reset.
 	 */
@@ -702,6 +704,7 @@ static void nau8360_dsp_switch(struct snd_soc_component *component, bool enable)
 	regmap_update_bits(regmap, NAU8360_R9D_PEQ_CTL, NAU8360_PEQ_BAND_MASK,
 		value << NAU8360_PEQ_BAND_SFT);
 
+	mutex_unlock(&nau8360->lock);
 }
 
 static int nau8360_dac_mux_put_enum(struct snd_kcontrol *kcontrol,
@@ -714,27 +717,26 @@ static int nau8360_dac_mux_put_enum(struct snd_kcontrol *kcontrol,
 	unsigned int *item = ucontrol->value.enumerated.item;
 	int ret = 0;
 
+	snd_soc_dapm_mutex_lock(dapm);
 	if (snd_soc_dapm_get_bias_level(dapm) > SND_SOC_BIAS_STANDBY) {
 		dev_warn_ratelimited(nau8360->dev, "changing path is not allowed during playback");
+		snd_soc_dapm_mutex_unlock(dapm);
 		return -EBUSY;
 	}
 
 	if (item[0] == NAU8360_DAC_SRC_DSP && !nau8360->load_fw_done) {
 		dev_warn_ratelimited(nau8360->dev, "Cannot enable DSP: Firmware not ready or disabled\n");
+		snd_soc_dapm_mutex_unlock(dapm);
 		return -EBUSY;
 	}
-
-	mutex_lock(&nau8360->lock);
+	snd_soc_dapm_mutex_unlock(dapm);
 
 	ret = snd_soc_dapm_put_enum_double(kcontrol, ucontrol);
 	if (ret <= 0)
-		goto unlock;
+		return ret;
 
 	nau8360_dsp_switch(component, snd_soc_enum_item_to_val(e, item[0]));
 
-unlock:
-	mutex_unlock(&nau8360->lock);
-
 	return ret;
 }
 
-- 
2.25.1

Re: [PATCH v5 1/2] ASoC: codecs: nau8360: Block DSP path selection when firmware load fails

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing `flush_work()` causes `alsactl` state restoration to sporadically fail on boot.
--

commit f48ac064e0d2cdb72be2043789666477aed5f727
Author: Neo Chang <YLCHANG2@nuvoton.com>

ASoC: codecs: nau8360: Block DSP path selection when firmware load fails

Block the DSP path selection if the firmware fails to load to prevent
invalid routing states.

If the firmware is not ready, nau8360_dac_mux_put_enum() will print
a rate-limited warning and return -EBUSY. This rejects the invalid
userspace request and maintains the original hardware state without
causing audio wrong status.

Closes: https://lore.kernel.org/linux-sound/aqK_oOpMAXVhxkHJ@stanley.mountain/

> diff --git a/sound/soc/codecs/nau8360.c b/sound/soc/codecs/nau8360.c
> index 89b8ee80d6c86..f5dee12127cd0 100644
> --- a/sound/soc/codecs/nau8360.c
> +++ b/sound/soc/codecs/nau8360.c
> @@ -715,8 +715,13 @@ static int nau8360_dac_mux_put_enum(struct snd_kcontrol *kcontrol,
>  	int ret = 0;
>  
>  	if (snd_soc_dapm_get_bias_level(dapm) > SND_SOC_BIAS_STANDBY) {
> -		dev_warn(nau8360->dev, "changing path is not allowed during playback");
> -		return ret;
> +		dev_warn_ratelimited(nau8360->dev, "changing path is not allowed during playback");
> +		return -EBUSY;
> +	}
> +
> +	if (item[0] == NAU8360_DAC_SRC_DSP && !nau8360->load_fw_done) {
> +		dev_warn_ratelimited(nau8360->dev, "Cannot enable DSP: Firmware not ready or disabled\n");
> +		return -EBUSY;

[Severity: Medium]
Will this cause boot-time ALSA state restoration to fail if the asynchronous
firmware loader is still running?

Userspace initialization tools like alsactl restore write to ALSA controls
immediately after card registration during boot. Because nau8360_load_fw_work
is scheduled asynchronously, nau8360->load_fw_done might still be false when
alsactl attempts to restore the DSP path.

Without a flush_work() call to synchronize with the firmware loader, does this
mean valid DSP routing configurations saved by the user will be sporadically
rejected during boot, causing the audio state to fall back to the default HW1
path?

>  	}
>  
>  	mutex_lock(&nau8360->lock);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260914015648.311986-1-YLCHANG2@nuvoton.com?part=1

Re: [PATCH v5 0/2] ASoC: codecs: nau8360: Fix DSP routing and deadlock issues

[Mark Brown]

On Mon, 14 Sep 2026 09:56:46 +0800, Neo Chang wrote:
> ASoC: codecs: nau8360: Fix DSP routing and deadlock issues
> 
> This patch series addresses two issues in the nau8360 codec driver
> regarding the DAC mux control:
> 
> 1. An invalid hardware routing state that occurs when the DSP firmware
>    fails to load but the userspace attempts to switch to the DSP path.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-7.3

Thanks!

[1/2] ASoC: codecs: nau8360: Block DSP path selection when firmware load fails
      https://git.kernel.org/broonie/sound/c/9231c12286ab
[2/2] ASoC: codecs: nau8360: Fix AB-BA deadlock in mux update
      https://git.kernel.org/broonie/sound/c/9b4647233ef5

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

Re: [PATCH v5 0/2] ASoC: codecs: nau8360: Fix DSP routing and deadlock issues

[Mark Brown]

On Mon, 14 Sep 2026 09:56:46 +0800, Neo Chang wrote:
> ASoC: codecs: nau8360: Fix DSP routing and deadlock issues
> 
> This patch series addresses two issues in the nau8360 codec driver
> regarding the DAC mux control:
> 
> 1. An invalid hardware routing state that occurs when the DSP firmware
>    fails to load but the userspace attempts to switch to the DSP path.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-7.4

Thanks!

[1/2] ASoC: codecs: nau8360: Block DSP path selection when firmware load fails
      https://git.kernel.org/broonie/sound/c/eeff736ebf5d
[2/2] ASoC: codecs: nau8360: Fix AB-BA deadlock in mux update
      https://git.kernel.org/broonie/sound/c/4862e73eaf08

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