MV-SILICON is a SoC manufacturer producing multifunctional audio SoCs.
Many devices built on top of their SDK share a common quirk that the
Playback and Capture mixers use linear volume with val = 0/4096/1.

The SDK seems to always report "MV-SILICON" for manufacturer string.
Hence, match it so that we don't need to define quirk table entries
separately for each devices. The "val = 0/4096/1" pattern is also
checked against before applying the quirk, in order that the quirk won't
accidentally break unseen variants.

Quirky device samples:

  usb 7-1: New USB device found, idVendor=1235, idProduct=0003, bcdDevice= 1.00
  usb 7-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  usb 7-1: Product: G1
  usb 7-1: Manufacturer: MV-SILICON
  usb 7-1: SerialNumber: 20190808

  usb 7-1: New USB device found, idVendor=1235, idProduct=0003, bcdDevice= 1.00
  usb 7-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  usb 7-1: Product: mvsilicon B1 usb audio
  usb 7-1: Manufacturer: MV-SILICON
  usb 7-1: SerialNumber: 20190808

  usb 5-1.4: New USB device found, idVendor=8888, idProduct=1719, bcdDevice= 1.00
  usb 5-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  usb 5-1.4: Product: HF310 USB Audio
  usb 5-1.4: Manufacturer: MV-SILICON
  usb 5-1.4: SerialNumber: 20190808

  usb 7-1: New USB device found, idVendor=2717, idProduct=5086, bcdDevice= 1.00
  usb 7-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  usb 7-1: Product: Redmi 电脑音箱
  usb 7-1: Manufacturer: MV-SILICON
  usb 7-1: SerialNumber: 20190808

  usb 2-1.2: New USB device found, idVendor=3142, idProduct=a601, bcdDevice= 1.00
  usb 2-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
  usb 2-1.2: Product: fifine Microphone
  usb 2-1.2: Manufacturer: MV-SILICON
  usb 2-1.2: SerialNumber: 20190808
  * https://forum.ubuntu-it.org/viewtopic.php?t=659345

Signed-off-by: Rong Zhang <i@rong.moe>
---
 sound/usb/mixer_quirks.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index 539044c0c6440..e97814dc90259 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -4588,6 +4588,24 @@ static void snd_dragonfly_quirk_db_scale(struct usb_mixer_interface *mixer,
 	}
 }
 
+static void snd_usb_mv_silicon_quirks(struct usb_mixer_interface *mixer,
+				      struct usb_mixer_elem_info *cval,
+				      struct snd_kcontrol *kctl)
+{
+	if (cval->min == 0 && cval->max == 4096 && cval->res == 1) {
+		/* The final effects will be printed later. */
+		usb_audio_info(mixer->chip, "applying MV-SILICON quirks (0/4096/1 variant)\n");
+
+		/* Respect MIN_MUTE set by module parameters. */
+		if (!(mixer->chip->quirk_flags & QUIRK_FLAG_MIXER_PLAYBACK_MIN_MUTE))
+			mixer->chip->quirk_flags |= QUIRK_FLAG_MIXER_PLAYBACK_LINEAR_VOL;
+		if (!(mixer->chip->quirk_flags & QUIRK_FLAG_MIXER_CAPTURE_MIN_MUTE))
+			mixer->chip->quirk_flags |= QUIRK_FLAG_MIXER_CAPTURE_LINEAR_VOL;
+	} else {
+		usb_audio_dbg(mixer->chip, "not applying MV-SILICON quirks on unknown variant");
+	}
+}
+
 /*
  * Some Plantronics headsets have control names that don't meet ALSA naming
  * standards. This function fixes nonstandard source names. By the time
@@ -4664,6 +4682,10 @@ void snd_usb_mixer_fu_apply_quirk(struct usb_mixer_interface *mixer,
 		break;
 	}
 
+	if (cval->control == UAC_FU_VOLUME &&
+	    !strncmp(mixer->chip->card->longname, "MV-SILICON", 10))
+		snd_usb_mv_silicon_quirks(mixer, cval, kctl);
+
 	/* lowest playback value is muted on some devices */
 	if (mixer->chip->quirk_flags & QUIRK_FLAG_MIXER_PLAYBACK_MIN_MUTE)
 		if (strstr(kctl->id.name, "Playback")) {
-- 
2.51.0