Re: Strange problem with USB device

[Larry Finger]

On 6/8/21 1:20 PM, Alan Stern wrote:
> On Tue, Jun 08, 2021 at 12:41:23PM -0500, Larry Finger wrote:
> > Hi,
> >
> > In https://bugzilla.suse.com/show_bug.cgi?id=1186889, a user is
> > reporting that his Bluetooth component of a Realtek RTL8822CE is not
>
> Is that a USB device?  That is, does it connect to the computer
> via a USB cable?  I'll assume it does...
>
> > being found in openSUSE's kernel 5.3.18. His lsusb scan is as follows:
> >
> > $ lsusb
> > Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
> > Bus 001 Device 003: ID 13d3:56c9 IMC Networks HP TrueVision HD Camera
> > Bus 001 Device 002: ID 045e:07fd Microsoft Corp. Nano Transceiver 1.1
> > Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
> >
> > The Bluetooth device is found and works in Windows 10, where the Device
> > Manager reports hardware ID's of 0bda:b00c. This combination is in
> > driver btusb.
> >
> > Is there a bug in the USB bus scan in kernel 5.3.18 that has since been
> > fixed, or is there still a bug that misses this device?
>
> Given only the information you have provided, it is impossible to
> answer that question.  Broadly speaking, lots of bugs in the USB
> subsystem have been fixed since kernel 5.3.18, but I don't know
> if any of them would affect detecting new devices on the bus like
> this.
>
> One thing you might try is to turn on USB debugging before
> plugging in the device:
>
> echo 'module usbcore =p' >/sys/kernel/debug/dynamic_debug/control
>
> The additional information this adds to the dmesg log may be
> helpful.

The BT device is part of the same card as the PCIe wifi device, thus there is no 
"plugging" it in a conventional sense. Is there some way to add the usbcore 
debugging statement to the kernel options line at boot time?

As I told GregKH, I am having the person with the problem try a rescue system 
with a 5.12 kernel.

Larry