[PATCH] ALSA: usb-audio: Add quirk for Redragon H510-PRO Wireless headset

[Agustin Luzardo]

The device with USB ID 040b:0897 (Weltrend Semiconductor chipset,
sold rebranded as the Redragon H510-PRO Wireless headset, reporting
"XiiSound Technology Corporation" in its USB string descriptors)
reports a constant value on GET_CUR for its PCM Playback Volume
control while still supporting an actually tunable volume. This
trips the sticky-value detection in check_sticky_volume_control(),
which disables the mixer control entirely:

  usb 1-4: 5:0: sticky mixer values (0/100/1 => 80), disabling

As a result, the device boots with playback volume effectively muted
and provides no way to raise it through the normal ALSA/PipeWire
mixer path.

Apply QUIRK_FLAG_MIXER_GET_CUR_BROKEN so the sticky check marks the
control as get_cur_broken and relies on the cached value instead of
disabling the mixer control outright.

Tested by backporting this quirk flag and the supporting
get_cur_broken logic onto a Linux 7.1.2-zen kernel build that does
not yet carry it, and confirming that after applying the flag the
kernel log changes from:

  usb 1-4: 5:0: sticky mixer values (0/100/1 => 80), disabling

to:

  usb 1-4: 5:0: broken mixer GET_CUR (0/100/1 => 80)

with the control usable via the driver's cached value afterward.

Signed-off-by: Agustin Luzardo <agustinluzardo09@xxxxxxxxx>
---
 sound/usb/quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 0000000..0000000 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -2211,6 +2211,8 @@
 	DEVICE_FLG(0x03f0, 0x654a, /* HP 320 FHD Webcam */
 		   QUIRK_FLAG_GET_SAMPLE_RATE | QUIRK_FLAG_MIC_RES_16),
+	DEVICE_FLG(0x040b, 0x0897, /* Weltrend Semiconductor, sold as Redragon H510-PRO Wireless headset */
+		   QUIRK_FLAG_MIXER_GET_CUR_BROKEN),
 	DEVICE_FLG(0x041e, 0x3000, /* Creative SB Extigy */
 		   QUIRK_FLAG_IGNORE_CTL_ERROR),
 	DEVICE_FLG(0x041e, 0x4080, /* Creative Live Cam VF0610 */
-- 
2.46.1