/* for alc285_fixup_ideapad_s740_coef() */
 #include "ideapad_s740_helper.c"
 
+static void alc256_fixup_tongfang_reset_persistent_settings(struct hda_codec *codec,
+                                                           const struct hda_fixup *fix,
+                                                           int action)
+{
+       /*
+       * A certain other OS sets these coeffs to different values. On at least one TongFang
+       * barebone these settings might survive even a cold reboot. So to restore a clean slate the
+       * values are explicitly reset to default here. Without this, the external microphone is
+       * always in a plugged-in state, while the internal microphone is always in an unplugged
+       * state, breaking the ability to use the internal microphone.
+       */
+       alc_write_coef_idx(codec, 0x24, 0x0000);
+       alc_write_coef_idx(codec, 0x26, 0x0000);
+       alc_write_coef_idx(codec, 0x29, 0x3000);
+       alc_write_coef_idx(codec, 0x37, 0xfe05);
+       alc_write_coef_idx(codec, 0x45, 0x5089);
+}
+
 enum {
        ALC269_FIXUP_GPIO2,
        ALC269_FIXUP_SONY_VAIO,
        ALC287_FIXUP_LEGION_15IMHG05_SPEAKERS,
        ALC287_FIXUP_LEGION_15IMHG05_AUTOMUTE,
        ALC287_FIXUP_YOGA7_14ITL_SPEAKERS,
-       ALC287_FIXUP_13S_GEN2_SPEAKERS
+       ALC287_FIXUP_13S_GEN2_SPEAKERS,
+       ALC256_FIXUP_TONGFANG_RESET_PERSISTENT_SETTINGS,
 };
 
 static const struct hda_fixup alc269_fixups[] = {
                .chained = true,
                .chain_id = ALC269_FIXUP_HEADSET_MODE,
        },
+       [ALC256_FIXUP_TONGFANG_RESET_PERSISTENT_SETTINGS] = {
+               .type = HDA_FIXUP_FUNC,
+               .v.func = alc256_fixup_tongfang_reset_persistent_settings,
+       },
 };
 
 static const struct snd_pci_quirk alc269_fixup_tbl[] = {
        SND_PCI_QUIRK(0x1b7d, 0xa831, "Ordissimo EVE2 ", ALC269VB_FIXUP_ORDISSIMO_EVE2), /* Also known as Malata PC-B1303 */
        SND_PCI_QUIRK(0x1c06, 0x2013, "Lemote A1802", ALC269_FIXUP_LEMOTE_A1802),
        SND_PCI_QUIRK(0x1c06, 0x2015, "Lemote A190X", ALC269_FIXUP_LEMOTE_A190X),
+       SND_PCI_QUIRK(0x1d05, 0x1132, "TongFang PHxTxX1", ALC256_FIXUP_TONGFANG_RESET_PERSISTENT_SETTINGS),
        SND_PCI_QUIRK(0x1d72, 0x1602, "RedmiBook", ALC255_FIXUP_XIAOMI_HEADSET_MIC),
        SND_PCI_QUIRK(0x1d72, 0x1701, "XiaomiNotebook Pro", ALC298_FIXUP_DELL1_MIC_NO_PRESENCE),
        SND_PCI_QUIRK(0x1d72, 0x1901, "RedmiBook 14", ALC256_FIXUP_ASUS_HEADSET_MIC),