[PATCH v2] ALSA: hda/realtek: Limit Line In boost and ADC gain on DECENTA MATX03

[PATCH v2] ALSA: hda/realtek: Limit Line In boost and ADC gain on DECENTA MATX03

[wangdich9700]

From: wangdicheng <wangdicheng@kylinos.cn>

The DECENTA MATX03 (ALC897, SSID 1e0b:1297) exposes a high gain
range on both the Line In pin boost and the ADC input amp. Pin 0x1a
reports nsteps=0x03 with stepsize=0x27, that is 0, 9.75, 19.5 and
29.25 dB. ADC 0x08 reports nsteps=0x3f with stepsize=0x02, that is
0 to 31.5 dB in 0.5 dB steps, and defaults to 0x3f (maximum). The
combined 60.75 dB analogue cascade overloads the front-end when the
source level is high, producing audible noise during Line In
monitoring.

Add a new fixup alc897_fixup_limit_linein_boost that overrides the
amp capabilities of pin 0x1a to nsteps=1 (max ~11.75 dB) and ADC
0x08 to nsteps=1 (max ~0.5 dB). The total gain drops from 60.75 dB
to ~12.25 dB, eliminating the clipping.

Signed-off-by: wangdicheng <wangdicheng@kylinos.cn>
---

v1->v2:
- Simplify the fixup function to use hard-coded NIDs (0x1a, 0x08)
  instead of generic pin/ADC iteration.
- Move the SND_PCI_QUIRK entry to the proper position sorted by
  PCI SSID order.
- Drop the model name addition from alc662_fixup_models[] since it
  is not needed.
---
 sound/hda/codecs/realtek/alc662.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/sound/hda/codecs/realtek/alc662.c b/sound/hda/codecs/realtek/alc662.c
index eff7c83b9c59..c1c7277b6754 100644
--- a/sound/hda/codecs/realtek/alc662.c
+++ b/sound/hda/codecs/realtek/alc662.c
@@ -198,6 +198,24 @@ static void alc897_fixup_lenovo_headset_mode(struct hda_codec *codec,
 	}
 }
 
+static void alc897_fixup_limit_linein_boost(struct hda_codec *codec,
+					    const struct hda_fixup *fix, int action)
+{
+	if (action != HDA_FIXUP_ACT_PROBE)
+		return;
+
+	snd_hda_override_amp_caps(codec, 0x1a, HDA_INPUT,
+				  (0x00 << AC_AMPCAP_OFFSET_SHIFT) |
+				  (0x01 << AC_AMPCAP_NUM_STEPS_SHIFT) |
+				  (0x2f << AC_AMPCAP_STEP_SIZE_SHIFT) |
+				  (0 << AC_AMPCAP_MUTE_SHIFT));
+	snd_hda_override_amp_caps(codec, 0x08, HDA_INPUT,
+				  (0x00 << AC_AMPCAP_OFFSET_SHIFT) |
+				  (0x01 << AC_AMPCAP_NUM_STEPS_SHIFT) |
+				  (0x02 << AC_AMPCAP_STEP_SIZE_SHIFT) |
+				  (0 << AC_AMPCAP_MUTE_SHIFT));
+}
+
 static const struct coef_fw alc668_coefs[] = {
 	WRITE_COEF(0x01, 0xbebe), WRITE_COEF(0x02, 0xaaaa), WRITE_COEF(0x03,    0x0),
 	WRITE_COEF(0x04, 0x0180), WRITE_COEF(0x06,    0x0), WRITE_COEF(0x07, 0x0f80),
@@ -326,6 +344,7 @@ enum {
 	ALC897_FIXUP_HEADSET_MIC_PIN3,
 	ALC662_FIXUP_CSL_GPIO,
 	ALC897_FIXUP_BEELINK_SER6_AMP,
+	ALC897_FIXUP_LIMIT_LINEIN_BOOST,
 };
 
 static const struct hda_fixup alc662_fixups[] = {
@@ -787,6 +806,10 @@ static const struct hda_fixup alc662_fixups[] = {
 		.type = HDA_FIXUP_FUNC,
 		.v.func = alc_fixup_gpio4,
 	},
+	[ALC897_FIXUP_LIMIT_LINEIN_BOOST] = {
+		.type = HDA_FIXUP_FUNC,
+		.v.func = alc897_fixup_limit_linein_boost,
+	},
 };
 
 static const struct hda_quirk alc662_fixup_tbl[] = {
@@ -857,6 +880,7 @@ static const struct hda_quirk alc662_fixup_tbl[] = {
 	SND_PCI_QUIRK(0x1b35, 0x1234, "CZC ET26", ALC662_FIXUP_CZC_ET26),
 	SND_PCI_QUIRK(0x1b35, 0x2206, "CZC P10T", ALC662_FIXUP_CZC_P10T),
 	SND_PCI_QUIRK(0x1c6c, 0x1239, "Compaq N14JP6-V2", ALC897_FIXUP_HP_HSMIC_VERB),
+	SND_PCI_QUIRK(0x1e0b, 0x1297, "DECENTA MATX03", ALC897_FIXUP_LIMIT_LINEIN_BOOST),
 	SND_PCI_QUIRK(0x1e63, 0x6d9a, "F+ FLAPTOP r", ALC897_FIXUP_HP_HSMIC_VERB),
 	SND_PCI_QUIRK(0x1f66, 0x0202, "Beelink SER6 Max 6900", ALC897_FIXUP_BEELINK_SER6_AMP),
 
-- 
2.25.1

Re: [PATCH v2] ALSA: hda/realtek: Limit Line In boost and ADC gain on DECENTA MATX03

[Takashi Iwai]

On Thu, 15 Oct 2026 04:12:10 +0200,
wangdich9700@163.com wrote:
> 
> From: wangdicheng <wangdicheng@kylinos.cn>
> 
> The DECENTA MATX03 (ALC897, SSID 1e0b:1297) exposes a high gain
> range on both the Line In pin boost and the ADC input amp. Pin 0x1a
> reports nsteps=0x03 with stepsize=0x27, that is 0, 9.75, 19.5 and
> 29.25 dB. ADC 0x08 reports nsteps=0x3f with stepsize=0x02, that is
> 0 to 31.5 dB in 0.5 dB steps, and defaults to 0x3f (maximum). The
> combined 60.75 dB analogue cascade overloads the front-end when the
> source level is high, producing audible noise during Line In
> monitoring.
> 
> Add a new fixup alc897_fixup_limit_linein_boost that overrides the
> amp capabilities of pin 0x1a to nsteps=1 (max ~11.75 dB) and ADC
> 0x08 to nsteps=1 (max ~0.5 dB). The total gain drops from 60.75 dB
> to ~12.25 dB, eliminating the clipping.
> 
> Signed-off-by: wangdicheng <wangdicheng@kylinos.cn>

Applied to for-next branch.  Thanks.


Takashi