Re: [BUG] Edifier QR30 (2d99:a101, Jieli Technology) reboots itself when RGB brightness button is used under Linux

[Michal Pecio <michal.pecio@gmail.com>]

On Sun, 9 Nov 2025 02:18:44 -0300, The-Luga wrote:
> The speaker has a physical knob that changes brightness. When the
> speaker is disconnected from any USB port, the knob works fine
> increasing/decreasing brightness. When connected to Windows, rotating
> the knob (either increase or decrease) changes brightness normally and
> the speaker does not reboot (without needing any vendor software).
> When connected to Linux, rotating the knob causes the speaker to
> reboot.
> 
> All brightness changes/reboots in the previous logs were done by
> rotating the speaker's physical knob.
> 
> I believe this is a firmware bug on the speaker. My hypothesis: after
> each brightness change the speaker expects a particular USB response
> (the default response Windows sends). If it does not receive that
> response, the speaker thinks it is disconnected and resets.

I haven't attempted decoding your usbmon traces, but based on Terry's
comments, the device disconnects immediately when the knob is rotated
without even sending any HID packet. The original trace begins with
root hub traffic - likely disconnect notification, followed by failure
of a URB waiting for HID data from the speaker, and new enumeration.

If anything, it looks like Linux is doing something to the speaker
which makes it enter an invalid internal state and then the firmware
panics next time the knob is rotated, before anything is sent.

I wonder if there is some way to block 'usbhid' from ever binding to
this device (not just unbinding it later) and see if that hepls?

What happens if you pass to Windows and back, then rotate the knob?

Regards,
Michal