potential bug or quirk in the linux kernel usb subsystem, usb microphone sampling rate resolution rate

["Hans Jörg Paliege" <hans_paliege@web.de>]

Hello Mr. Kroah-Hartman,



my name is Hans Paliege and i am a longtime Linux user, but i came 
across a potential peculiar quirk or bug in the usb subsystem

that may need your attention. According to the kernel documentation i 
should contact You as the main developer directly.



I am using a debian unstable amd64 build that is updated daily, and 
during boot for about two weeks now

the audio frequency sample rate of my logitech C270 usb webcam is no 
longer initialized correctly.

As a result the webcam only delivers video but no audio. The webcam 
microphone is as a audio device recognized

by the webbrowser but the input is null.



During boot the dmesg error messages are:


[ +0,007125] usb 3-1: current rate 24000 is different from the runtime 
rate 16000
[ +0,002572] usb 3-1: 3:3: cannot set freq 24000 to ep 0x82



After manual usbreset of the logitech C270 webcam the dmesg error 
messages are:


[Mär 2 22:13] usb 3-6.2: reset full-speed USB device number 7 using xhci_hcd
[ +12,959814] usb 3-1: reset high-speed USB device number 2 using xhci_hcd
[ +0,288046] uvcvideo 3-1:1.0: Found UVC 1.00 device C270 HD WEBCAM 
(046d:0825)
[ +0,036940] usb 3-1: current rate 16000 is different from the runtime 
rate 32000
[ +0,063995] usb 3-1: current rate 24000 is different from the runtime 
rate 16000
[ +0,061679] usb 3-1: 3:3: cannot set freq 24000 to ep 0x82
[ +0,213449] usb 3-1: set resolution quirk: cval->res = 384




After some internet search i could not find any specific command, 
application or grub boot parameter to manually set the rate to the 
runtime rate of 16000 or 32000.

The quirk seems to be, that the sampling rate is automatically set to 
the value of 24000, while the actual working runtime rates are ignored.


Any subsequent pipewire-alsa related audio volume and input/output works 
fine, and i have to use a really old ZOOM H2 usb microphone at 44100 
that works for now.




Maybe a recent change in the linux kernel or the usb subsytem caused 
this. It would be great if you could take a closer look at it and fix it.



Thank you very much.


Best regards

Hans Paliege