Re: [BUG] snd-usb-audio: incorrect PCM volume scaling on Edifier R19U USB speaker (0001:0201)

On Mon, 06 Jul 2026 01:07:46 +0200,
Miguel Mário Nápoli wrote:
> 
> 
> Hello,
> 
> I'd like to report an issue with USB audio volume scaling on a cheap
> USB-powered speaker set, in case it's useful for a mixer quirk fix.
> 
> Device: Edifier R19U USB speakers (MVSILICON.INC. controller chip)
> lsusb: Bus 001 Device 010: ID 0001:0201 Fry's Electronics EDIFIER R19U
>   (Note: idVendor 0001 is an unofficial/reused ID ("Fry's Electronics"
>   placeholder), so it may be shared by unrelated devices from other
>   vendors -- please take that into account if considering a quirk
>   based on VID/PID matching alone.)
> 
> System: Zorin OS 18 (Ubuntu-based), fresh install (< 1 week old)
> Kernel: 6.17.0-35-generic
> PipeWire: 1.0.5
> 
> Problem description:
> On connection, the kernel logs a warning about an unusually large
> volume range for this device's PCM control:
> 
>   usb 1-2: New USB device found, idVendor=0001, idProduct=0201, bcdDevice=0.10
>   usb 1-2: Product: EDIFIER R19U
>   usb 1-2: Manufacturer: MVSILICON.INC.
>   usb 1-2: Warning! Unlikely big volume range (=999), cval->res is probably
> wrong.
>   usb 1-2: [9] FU [PCM Playback Volume] ch = 2, val = 0/999/1
> 
> As a result, userspace volume controls (tested via PipeWire/WirePlumber
> and GNOME Sound Settings) display a normal-looking volume percentage
> (e.g. 69%), while the actual underlying ALSA mixer value stays at 0,
> producing no audible output at all -- with no mute indicator anywhere
> in the UI.
> 
> Confirmed via amixer while PipeWire reported ~69%:
> 
>   Simple mixer control 'PCM',0
>     Capabilities: pvolume pswitch pswitch-joined
>     Playback channels: Front Left - Front Right
>     Limits: Playback 0 - 999
>     Front Left: Playback 0 [0%] [0.00dB] [on]
>     Front Right: Playback 0 [0%] [0.00dB] [on]
> 
> Manually forcing the raw ALSA control resolves it immediately:
> 
>   amixer -c <card> sset PCM 999
> 
> After this, audio plays correctly and the volume responds normally to
> further adjustments, confirming the hardware/DAC path itself is fine --
> this looks like a resolution/step (cval->res) miscalculation for this
> device's 0-999 range, similar to past quirk fixes for other USB audio
> chips with non-standard volume ranges (e.g. the Logitech c270 webcam
> fix in sound/usb/mixer.c, volume_control_quirks()).
> 
> This was not an issue on a previous Ubuntu installation with an older
> kernel/PipeWire stack on the same hardware, suggesting this may be a
> regression in how a newer kernel or PipeWire handles this specific
> range, or simply a device that was never covered by an existing quirk.
> 
> Current workaround in use (userspace, not a real fix):
> A udev rule triggers `amixer -c <card> sset PCM 999` whenever the
> device is connected (matched by idVendor=0001/idProduct=0201), forcing
> the ALSA control to maximum so PipeWire's own volume slider can then
> attenuate correctly from there.
> 
> Happy to test a patch or provide more logs/output if needed.

Have you tried to apply the existing quirk?  Judging from the number
999, it might be a linear volume, and you can apply the linear volume
quirk.  See Documentation/sound/alsa-configuration.rst, the section
for snd-usb-audio quirk_flags.


thanks,

Takashi