Re: [PATCH] Fix mic sound on Jieli webcam

[Marco Giunta <giun7a@gmail.com>]

On Thu, Dec 17, 2020 at 3:12 PM Takashi Iwai <tiwai@suse.de> wrote:
>
> Thanks.
>
> >     Interface Association:
> >       bLength                 8
> >       bDescriptorType        11
> >       bFirstInterface         2
> >       bInterfaceCount         2
> >       bFunctionClass          1 Audio
> >       bFunctionSubClass       2 Streaming
> >       bFunctionProtocol       0
> >       iFunction               5 USB Microphone
> >     Interface Descriptor:
> (snip)
> >       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]         8000
> >       Endpoint Descriptor:
> >         bLength                 9
> >         bDescriptorType         5
> >         bEndpointAddress     0x82  EP 2 IN
> >         bmAttributes            1
> >           Transfer Type            Isochronous
> >           Synch Type               None
> >           Usage Type               Data
> >         wMaxPacketSize     0x0100  1x 256 bytes
> >         bInterval               4
>
> It's 4, and the same is set for all sample rates (8000, 16000, 44100,
> 48000).
>
> If you don't tweak the datainterval, which error do you get?
> The actual error message should appear before "... xx callbacks
> suppressed" line.

Without the tweak, only error messages are:

kernel: usb 1-8: current rate 0 is different from the runtime rate 8000
kernel: usb 1-8: current rate 0 is different from the runtime rate 16000
kernel: usb 1-8: current rate 0 is different from the runtime rate 44100
kernel: usb 1-8: current rate 0 is different from the runtime rate 48000
kernel: usb 1-8: Warning! Unlikely big volume range (=4096), cval->res
is probably wrong.
kernel: usb 1-8: [3] FU [Mic Capture Volume] ch = 1, val = 0/4096/1

but recording from mic at any rate (8000, 16000, 44100, 48000) results
in an incomprehensible sound, like Minion voice.

With your patch 'ALSA: usb-audio: Disable sample read check if
firmware  doesn't give back' error messages have gone away, but result
is the same: Minion voice.

Thanks,
  Marco