[PATCH 6.1 019/131] ALSA: usb-audio: Fix microphone sound on Nexigo webcam.

Greg Kroah-Hartman
2023-10-16T08:52:42Z

From: Christos Skevis <xristos.thes@gmail.com>

commit 4a63e68a295187ae3c1cb3fa0c583c96a959714f upstream.

I own an external usb Webcam, model NexiGo N930AF, which had low mic volume and
inconsistent sound quality. Video works as expected.

(snip)
[ +0.047857] usb 5-1: new high-speed USB device number 2 using xhci_hcd
[ +0.003406] usb 5-1: New USB device found, idVendor=1bcf, idProduct=2283, bcdDevice=12.17
[ +0.000007] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ +0.000004] usb 5-1: Product: NexiGo N930AF FHD Webcam
[ +0.000003] usb 5-1: Manufacturer: SHENZHEN AONI ELECTRONIC CO., LTD
[ +0.000004] usb 5-1: SerialNumber: 20201217011
[ +0.003900] usb 5-1: Found UVC 1.00 device NexiGo N930AF FHD Webcam (1bcf:2283)
[ +0.025726] usb 5-1: 3:1: cannot get usb sound sample rate freq at ep 0x86
[ +0.071482] usb 5-1: 3:2: cannot get usb sound sample rate freq at ep 0x86
[ +0.004679] usb 5-1: 3:3: cannot get usb sound sample rate freq at ep 0x86
[ +0.051607] usb 5-1: Warning! Unlikely big volume range (=4096), cval->res is probably wrong.
[ +0.000005] usb 5-1: [7] FU [Mic Capture Volume] ch = 1, val = 0/4096/1

Set up quirk cval->res to 16 for 256 levels,
Set GET_SAMPLE_RATE quirk flag to stop trying to get the sample rate.
Confirmed that happened anyway later due to the backoff mechanism, after 3 failures

All audio stream on device interfaces share the same values,
apart from wMaxPacketSize and tSamFreq :

(snip)
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 3
bNumEndpoints 1
bInterfaceClass 1 Audio
bInterfaceSubClass 2 Streaming
bInterfaceProtocol 0
iInterface 0
AudioStreaming Interface Descriptor:
bLength 7
bDescriptorType 36
bDescriptorSubtype 1 (AS_GENERAL)
bTerminalLink 8
bDelay 1 frames
wFormatTag 0x0001 PCM
AudioStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 1
bSubframeSize 2
bBitResolution 16
bSamFreqType 1 Discrete
tSamFreq[ 0] 44100
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x86 EP 6 IN
bmAttributes 5
Transfer Type Isochronous
Synch Type Asynchronous
Usage Type Data
wMaxPacketSize 0x005c 1x 92 bytes
bInterval 4
bRefresh 0
bSynchAddress 0
AudioStreaming Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0x0000
(snip)

Based on the usb data about manufacturer, SPCA2281B3 is the most likely controller IC
Manufacturer does not provide link for datasheet nor detailed specs.
No way to confirm if the firmware supports any other way of getting the sample rate.

Testing patch provides consistent good sound recording quality and volume range.

(snip)
[ +0.045764] usb 5-1: new high-speed USB device number 2 using xhci_hcd
[ +0.106290] usb 5-1: New USB device found, idVendor=1bcf, idProduct=2283, bcdDevice=12.17
[ +0.000006] usb 5-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ +0.000004] usb 5-1: Product: NexiGo N930AF FHD Webcam
[ +0.000003] usb 5-1: Manufacturer: SHENZHEN AONI ELECTRONIC CO., LTD
[ +0.000004] usb 5-1: SerialNumber: 20201217011
[ +0.043700] usb 5-1: set resolution quirk: cval->res = 16
[ +0.002585] usb 5-1: Found UVC 1.00 device NexiGo N930AF FHD Webcam (1bcf:2283)

Signed-off-by: Christos Skevis <xristos.thes@gmail.com>
Link: https://lore.kernel.org/r/20231006155330.399393-1-xristos.thes@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
sound/usb/mixer.c | 7 +++++++
sound/usb/quirks.c | 2 ++
2 files changed, 9 insertions(+)

--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1204,6 +1204,13 @@ static void volume_control_quirks(struct
cval->res = 16;
}
break;
+ case USB_ID(0x1bcf, 0x2283): /* NexiGo N930AF FHD Webcam */
+ if (!strcmp(kctl->id.name, "Mic Capture Volume")) {
+ usb_audio_info(chip,
+ "set resolution quirk: cval->res = 16\n");
+ cval->res = 16;
+ }
+ break;
}
}

--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -2175,6 +2175,8 @@ static const struct usb_audio_quirk_flag
QUIRK_FLAG_FIXED_RATE),
DEVICE_FLG(0x0ecb, 0x2069, /* JBL Quantum810 Wireless */
QUIRK_FLAG_FIXED_RATE),
+ DEVICE_FLG(0x1bcf, 0x2283, /* NexiGo N930AF FHD Webcam */
+ QUIRK_FLAG_GET_SAMPLE_RATE),

/* Vendor matches */
VENDOR_FLG(0x045e, /* MS Lifecam */