[PATCH] ASoC: fsl_micfil: Add DC output remover control

[PATCH] ASoC: fsl_micfil: Add DC output remover control

[Shengjiu Wang]

Add support for the DC output remover feature available on i.MX93 and
newer platforms. This allows users to configure the output DC removal
filter with cut-off frequencies of 20Hz, 13.3Hz, 40Hz, or bypass it
entirely.

The control is exposed as an ALSA mixer control and defaults to bypass
mode. It is only available on platforms with the use_verid flag set
(i.MX93+).

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
---
 sound/soc/fsl/fsl_micfil.c | 79 ++++++++++++++++++++++++++++++++++++++
 sound/soc/fsl/fsl_micfil.h |  1 +
 2 files changed, 80 insertions(+)

diff --git a/sound/soc/fsl/fsl_micfil.c b/sound/soc/fsl/fsl_micfil.c
index 2e887f1f1f36..60ac8eabab9d 100644
--- a/sound/soc/fsl/fsl_micfil.c
+++ b/sound/soc/fsl/fsl_micfil.c
@@ -74,6 +74,7 @@ struct fsl_micfil {
 	int irq[MICFIL_IRQ_LINES];
 	enum quality quality;
 	int dc_remover;
+	int dc_out_remover;
 	int vad_init_mode;
 	int vad_enabled;
 	int vad_detected;
@@ -347,6 +348,11 @@ static const char * const micfil_dc_remover_texts[] = {
 	"Cut-off @152Hz", "Bypass",
 };
 
+static const char * const micfil_dc_out_remover_texts[] = {
+	"Cut-off @20Hz", "Cut-off @13.3Hz",
+	"Cut-off @40Hz", "Bypass",
+};
+
 static const struct soc_enum hwvad_enable_enum =
 	SOC_ENUM_SINGLE_EXT(ARRAY_SIZE(micfil_hwvad_enable),
 			    micfil_hwvad_enable);
@@ -360,6 +366,9 @@ static const struct soc_enum hwvad_hpf_enum =
 static const struct soc_enum fsl_micfil_dc_remover_enum =
 	SOC_ENUM_SINGLE_EXT(ARRAY_SIZE(micfil_dc_remover_texts),
 			    micfil_dc_remover_texts);
+static const struct soc_enum fsl_micfil_dc_out_remover_enum =
+	SOC_ENUM_SINGLE_EXT(ARRAY_SIZE(micfil_dc_out_remover_texts),
+			    micfil_dc_out_remover_texts);
 
 static int micfil_put_dc_remover_state(struct snd_kcontrol *kcontrol,
 				       struct snd_ctl_elem_value *ucontrol)
@@ -405,6 +414,50 @@ static int micfil_get_dc_remover_state(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
+static int micfil_put_dc_out_remover_state(struct snd_kcontrol *kcontrol,
+					   struct snd_ctl_elem_value *ucontrol)
+{
+	struct soc_enum *e = (struct soc_enum *)kcontrol->private_value;
+	struct snd_soc_component *comp = snd_kcontrol_chip(kcontrol);
+	struct fsl_micfil *micfil = snd_soc_component_get_drvdata(comp);
+	unsigned int *item = ucontrol->value.enumerated.item;
+	int val = snd_soc_enum_item_to_val(e, item[0]);
+	int i = 0, ret = 0;
+	u32 reg_val = 0;
+
+	if (val < 0 || val > 3)
+		return -EINVAL;
+
+	ret = pm_runtime_resume_and_get(comp->dev);
+	if (ret)
+		return ret;
+
+	micfil->dc_out_remover = val;
+
+	/* Calculate total value for all channels */
+	for (i = 0; i < MICFIL_OUTPUT_CHANNELS; i++)
+		reg_val |= val << MICFIL_DC_CHX_SHIFT(i);
+
+	/* Update DC Remover mode for all channels */
+	ret = snd_soc_component_update_bits(comp, REG_MICFIL_DC_OUT_CTRL,
+					    MICFIL_DC_CTRL_CONFIG, reg_val);
+
+	pm_runtime_put_autosuspend(comp->dev);
+
+	return ret;
+}
+
+static int micfil_get_dc_out_remover_state(struct snd_kcontrol *kcontrol,
+					   struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_soc_component *comp = snd_kcontrol_chip(kcontrol);
+	struct fsl_micfil *micfil = snd_soc_component_get_drvdata(comp);
+
+	ucontrol->value.enumerated.item[0] = micfil->dc_out_remover;
+
+	return 0;
+}
+
 static int hwvad_put_enable(struct snd_kcontrol *kcontrol,
 			    struct snd_ctl_elem_value *ucontrol)
 {
@@ -525,6 +578,11 @@ static const struct snd_kcontrol_new fsl_micfil_volume_sx_controls[] = {
 			  MICFIL_OUTGAIN_CHX_SHIFT(7), 0x8, 0xF, gain_tlv),
 };
 
+static const struct snd_kcontrol_new fsl_micfil_dc_out_controls[] = {
+	SOC_ENUM_EXT("MICFIL DC Out Remover Control", fsl_micfil_dc_out_remover_enum,
+		     micfil_get_dc_out_remover_state, micfil_put_dc_out_remover_state),
+};
+
 static const struct snd_kcontrol_new fsl_micfil_snd_controls[] = {
 	SOC_ENUM_EXT("MICFIL Quality Select",
 		     fsl_micfil_quality_enum,
@@ -1047,6 +1105,19 @@ static int fsl_micfil_dai_probe(struct snd_soc_dai *cpu_dai)
 	}
 	micfil->dc_remover = MICFIL_DC_BYPASS;
 
+	if (micfil->soc->use_verid) {
+		val = 0;
+		for (i = 0; i < MICFIL_OUTPUT_CHANNELS; i++)
+			val |= MICFIL_DC_BYPASS << MICFIL_DC_CHX_SHIFT(i);
+		ret = regmap_update_bits(micfil->regmap, REG_MICFIL_DC_OUT_CTRL,
+					 MICFIL_DC_CTRL_CONFIG, val);
+		if (ret) {
+			dev_err(dev, "failed to set DC OUT Remover mode bits\n");
+			return ret;
+		}
+		micfil->dc_out_remover = MICFIL_DC_BYPASS;
+	}
+
 	snd_soc_dai_init_dma_data(cpu_dai, NULL,
 				  &micfil->dma_params_rx);
 
@@ -1071,6 +1142,10 @@ static int fsl_micfil_component_probe(struct snd_soc_component *component)
 		snd_soc_add_component_controls(component, fsl_micfil_range_controls,
 					       ARRAY_SIZE(fsl_micfil_range_controls));
 
+	if (micfil->soc->use_verid)
+		snd_soc_add_component_controls(component, fsl_micfil_dc_out_controls,
+					       ARRAY_SIZE(fsl_micfil_dc_out_controls));
+
 	return 0;
 }
 
@@ -1117,6 +1192,7 @@ static const struct reg_default fsl_micfil_reg_defaults[] = {
 	{REG_MICFIL_DATACH6,		0x00000000},
 	{REG_MICFIL_DATACH7,		0x00000000},
 	{REG_MICFIL_DC_CTRL,		0x00000000},
+	{REG_MICFIL_DC_OUT_CTRL,	0x00000000},
 	{REG_MICFIL_OUT_CTRL,		0x00000000},
 	{REG_MICFIL_OUT_STAT,		0x00000000},
 	{REG_MICFIL_VAD0_CTRL1,		0x00000000},
@@ -1143,6 +1219,7 @@ static const struct reg_default fsl_micfil_reg_defaults_v2[] = {
 	{REG_MICFIL_DATACH6 - 0x4,	0x00000000},
 	{REG_MICFIL_DATACH7 - 0x4,	0x00000000},
 	{REG_MICFIL_DC_CTRL,		0x00000000},
+	{REG_MICFIL_DC_OUT_CTRL,	0x00000000},
 	{REG_MICFIL_OUT_CTRL,		0x00000000},
 	{REG_MICFIL_OUT_STAT,		0x00000000},
 	{REG_MICFIL_VAD0_CTRL1,		0x00000000},
@@ -1179,6 +1256,7 @@ static bool fsl_micfil_readable_reg(struct device *dev, unsigned int reg)
 	case REG_MICFIL_VAD0_NDATA:
 	case REG_MICFIL_VAD0_ZCD:
 		return true;
+	case REG_MICFIL_DC_OUT_CTRL:
 	case REG_MICFIL_FSYNC_CTRL:
 	case REG_MICFIL_VERID:
 	case REG_MICFIL_PARAM:
@@ -1210,6 +1288,7 @@ static bool fsl_micfil_writeable_reg(struct device *dev, unsigned int reg)
 	case REG_MICFIL_VAD0_NCONFIG:
 	case REG_MICFIL_VAD0_ZCD:
 		return true;
+	case REG_MICFIL_DC_OUT_CTRL:
 	case REG_MICFIL_FSYNC_CTRL:
 		if (micfil->soc->use_verid)
 			return true;
diff --git a/sound/soc/fsl/fsl_micfil.h b/sound/soc/fsl/fsl_micfil.h
index fdfe4e7125bc..e271c6073f42 100644
--- a/sound/soc/fsl/fsl_micfil.h
+++ b/sound/soc/fsl/fsl_micfil.h
@@ -22,6 +22,7 @@
 #define REG_MICFIL_DATACH6		0x3C
 #define REG_MICFIL_DATACH7		0x40
 #define REG_MICFIL_DC_CTRL		0x64
+#define REG_MICFIL_DC_OUT_CTRL		0x68
 #define REG_MICFIL_OUT_CTRL		0x74
 #define REG_MICFIL_OUT_STAT		0x7C
 #define REG_MICFIL_FSYNC_CTRL		0x80
-- 
2.34.1

Re: [PATCH] ASoC: fsl_micfil: Add DC output remover control

[Mark Brown]

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On Mon, Apr 20, 2026 at 04:53:44PM +0800, Shengjiu Wang wrote:

> +static int micfil_put_dc_out_remover_state(struct snd_kcontrol *kcontrol,
> +					   struct snd_ctl_elem_value *ucontrol)
> +{

> +	if (val < 0 || val > 3)
> +		return -EINVAL;
> +
> +	ret = pm_runtime_resume_and_get(comp->dev);
> +	if (ret)
> +		return ret;
> +
> +	micfil->dc_out_remover = val;

...

> +	/* Update DC Remover mode for all channels */
> +	ret = snd_soc_component_update_bits(comp, REG_MICFIL_DC_OUT_CTRL,
> +					    MICFIL_DC_CTRL_CONFIG, reg_val);
> +
> +	pm_runtime_put_autosuspend(comp->dev);
> +
> +	return ret;

This will return 0 not 1 when the value changes, meaning event
generation is missed.  The mixer-test selftest should report this.

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Re: [PATCH] ASoC: fsl_micfil: Add DC output remover control

[Shengjiu Wang]

On Mon, Apr 20, 2026 at 8:50 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Mon, Apr 20, 2026 at 04:53:44PM +0800, Shengjiu Wang wrote:
>
> > +static int micfil_put_dc_out_remover_state(struct snd_kcontrol *kcontrol,
> > +                                        struct snd_ctl_elem_value *ucontrol)
> > +{
>
> > +     if (val < 0 || val > 3)
> > +             return -EINVAL;
> > +
> > +     ret = pm_runtime_resume_and_get(comp->dev);
> > +     if (ret)
> > +             return ret;
> > +
> > +     micfil->dc_out_remover = val;
>
> ...
>
> > +     /* Update DC Remover mode for all channels */
> > +     ret = snd_soc_component_update_bits(comp, REG_MICFIL_DC_OUT_CTRL,
> > +                                         MICFIL_DC_CTRL_CONFIG, reg_val);
> > +
> > +     pm_runtime_put_autosuspend(comp->dev);
> > +
> > +     return ret;
>
> This will return 0 not 1 when the value changes, meaning event
> generation is missed.  The mixer-test selftest should report this.

snd_soc_component_update_bits() will return 1 if the value is changed.
and the mixer-test pass

ok 120 get_value.micfilaudio.8
# micfilaudio.8 MICFIL DC Out Remover Control
ok 121 name.micfilaudio.8
ok 122 write_default.micfilaudio.8
ok 123 write_valid.micfilaudio.8
ok 124 write_invalid.micfilaudio.8
ok 125 event_missing.micfilaudio.8
ok 126 event_spurious.micfilaudio.8

Is there something I missed here?

Best regards
Shengjiu Wang

Re: [PATCH] ASoC: fsl_micfil: Add DC output remover control

[Mark Brown]

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On Tue, Apr 21, 2026 at 03:40:12PM +0800, Shengjiu Wang wrote:
> On Mon, Apr 20, 2026 at 8:50 PM Mark Brown <broonie@kernel.org> wrote:

> > > +     /* Update DC Remover mode for all channels */
> > > +     ret = snd_soc_component_update_bits(comp, REG_MICFIL_DC_OUT_CTRL,
> > > +                                         MICFIL_DC_CTRL_CONFIG, reg_val);

> > This will return 0 not 1 when the value changes, meaning event
> > generation is missed.  The mixer-test selftest should report this.

> snd_soc_component_update_bits() will return 1 if the value is changed.
> and the mixer-test pass

Ah, so it will - I'm used to the regmap one which doesn't do that and
instead has a separate function to get a bool back for changes.  The
code is fine

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Re: [PATCH] ASoC: fsl_micfil: Add DC output remover control

[Mark Brown]

On Mon, 20 Apr 2026 16:53:44 +0800, Shengjiu Wang wrote:
> ASoC: fsl_micfil: Add DC output remover control

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-7.2

Thanks!

[1/1] ASoC: fsl_micfil: Add DC output remover control
      https://git.kernel.org/broonie/sound/c/e9a6f077e415

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