[PATCH] ALSA: usb-audio: skip the broken mute control on AVerMedia GC553Pro

[Asai Neko]

Skip the nonfunctional master mute control on the AVerMedia Live Gamer
ULTRA S GC553Pro (07ca:1553).

USB tracing shows that GET_CUR returns zero bytes instead of the required
one-byte value, both through usbfs and during ALSA initialization.
SET_CUR succeeds, but switching capture off does not mute HDMI audio.

Before the change, the driver exposed a misleading PCM Capture Switch
and logged: 3:2: failed to get current value for ch 0 (-22)

With the patch applied, the switch and warning are absent. A ten-second
sound recording through PipeWire confirmed that stereo 48 kHz, 16-bit
capture still works.

Tested on NixOS with the patched 7.3.0-rc3 kernel. The USB audio driver
object builds with Clang and W=1; sparse and strict checkpatch pass.

Signed-off-by: Asai Neko <sugar@xxxxxxx>
---
Skip the broken mute control on the AVerMedia Live Gamer ULTRA S GC553Pro.
Testing details and the rationale are included in the patch commit message.
---
 sound/usb/mixer_maps.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/sound/usb/mixer_maps.c b/sound/usb/mixer_maps.c
index 69093c666282..41454cb403d0 100644
--- a/sound/usb/mixer_maps.c
+++ b/sound/usb/mixer_maps.c
@@ -531,6 +531,15 @@ static const struct usbmix_name_map audient_id24_map[] = {
 	{}
 };
 
+/*
+ * The GC553Pro returns no data for GET_CUR on its advertised mute control.
+ * SET_CUR succeeds but does not mute capture, so skip the control entirely.
+ */
+static const struct usbmix_name_map avermedia_gc553pro_map[] = {
+	{ 3, NULL, UAC_FU_MUTE },
+	{}
+};
+
 /*
  * Control map entries
  */
@@ -577,6 +586,10 @@ static const struct usbmix_ctl_map usbmix_ctl_maps[] = {
 		.id = USB_ID(0x0763, 0x2031),
 		.selector_map = c400_selectors,
 	},
+	{
+		.id = USB_ID(0x07ca, 0x1553),
+		.map = avermedia_gc553pro_map,
+	},
 	{
 		.id = USB_ID(0x08bb, 0x2702),
 		.map = linex_map,

---
base-commit: 704340f1cd0dcef829eb62f5b48ae95a2ce17bdf
change-id: 20260914-avermedia-gc553pro-alsa-cce3f0a6db70

Best regards,
--  
Asai Neko <sugar@xxxxxxx>


-- 
Asai Neko