[PATCH] ALSA: hda/realtek: Limit Line In boost and ADC gain on DECENTA MATX03
From: wangdich9700
Date: Tue Oct 13 2026 - 08:29:07 EST
From: wangdicheng <wangdicheng@xxxxxxxxxx>
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 harmonic distortion during
Line In monitoring.
Add a new fixup alc897_fixup_limit_linein_boost that overrides the amp
capabilities of the Line In and external Mic pins to nsteps=1 (max
~11.75 dB), and also limits the ADC input amp to nsteps=1 (max ~0.5 dB).
The total gain drops from 60.75 dB to ~12.25 dB, eliminating the
clipping. Internal and dock mic pins are excluded to avoid affecting
built-in microphones.
Tested on the affected machine: with the fixup applied, Line In
recording at maximum source volume is clean, and dmesg confirms the
fixup is picked:
ALC897: picked fixup alc897-limit-linein-boost (SSID)
Signed-off-by: wangdicheng <wangdicheng@xxxxxxxxxx>
---
sound/hda/codecs/realtek/alc662.c | 50 +++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/sound/hda/codecs/realtek/alc662.c b/sound/hda/codecs/realtek/alc662.c
index eff7c83b9c59..a140891d51fa 100644
--- a/sound/hda/codecs/realtek/alc662.c
+++ b/sound/hda/codecs/realtek/alc662.c
@@ -198,6 +198,49 @@ 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)
+{
+ struct alc_spec *spec = codec->spec;
+ struct auto_pin_cfg *cfg = &spec->gen.autocfg;
+ int i;
+
+ if (action != HDA_FIXUP_ACT_PROBE)
+ return;
+
+ for (i = 0; i < cfg->num_inputs; i++) {
+ hda_nid_t nid = cfg->inputs[i].pin;
+ unsigned int defcfg;
+
+ if (cfg->inputs[i].type != AUTO_PIN_LINE_IN &&
+ cfg->inputs[i].type != AUTO_PIN_MIC)
+ continue;
+
+ defcfg = snd_hda_codec_get_pincfg(codec, nid);
+ if (snd_hda_get_input_pin_attr(defcfg) == INPUT_PIN_ATTR_INT ||
+ snd_hda_get_input_pin_attr(defcfg) == INPUT_PIN_ATTR_DOCK)
+ continue;
+
+ snd_hda_override_amp_caps(codec, nid, HDA_INPUT,
+ (0x00 << AC_AMPCAP_OFFSET_SHIFT) |
+ (0x01 << AC_AMPCAP_NUM_STEPS_SHIFT) |
+ (0x2f << AC_AMPCAP_STEP_SIZE_SHIFT) |
+ (0 << AC_AMPCAP_MUTE_SHIFT));
+ }
+
+ for (i = 0; i < spec->gen.num_all_adcs; i++) {
+ hda_nid_t adc = spec->gen.all_adcs[i];
+ unsigned int caps;
+
+ caps = query_amp_caps(codec, adc, HDA_INPUT);
+ if ((caps & AC_AMPCAP_NUM_STEPS) >> AC_AMPCAP_NUM_STEPS_SHIFT > 1) {
+ caps &= ~AC_AMPCAP_NUM_STEPS;
+ caps |= (0x01 << AC_AMPCAP_NUM_STEPS_SHIFT);
+ snd_hda_override_amp_caps(codec, adc, HDA_INPUT, caps);
+ }
+ }
+}
+
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 +369,7 @@ 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 +831,10 @@ 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[] = {
@@ -859,6 +907,7 @@ static const struct hda_quirk alc662_fixup_tbl[] = {
SND_PCI_QUIRK(0x1c6c, 0x1239, "Compaq N14JP6-V2", ALC897_FIXUP_HP_HSMIC_VERB),
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),
+ SND_PCI_QUIRK(0x1e0b, 0x1297, "DECENTA MATX03", ALC897_FIXUP_LIMIT_LINEIN_BOOST),
#if 0
/* Below is a quirk table taken from the old code.
@@ -954,6 +1003,7 @@ static const struct hda_model_fixup alc662_fixup_models[] = {
{.id = ALC662_FIXUP_LENOVO_MULTI_CODECS, .name = "dual-codecs"},
{.id = ALC669_FIXUP_ACER_ASPIRE_ETHOS, .name = "aspire-ethos"},
{.id = ALC897_FIXUP_UNIS_H3C_X500S, .name = "unis-h3c-x500s"},
+ {.id = ALC897_FIXUP_LIMIT_LINEIN_BOOST, .name = "alc897-limit-linein-boost"},
{}
};
--
2.25.1