Messages in this thread | | | Date | Tue, 8 Jun 2021 14:53:14 -0400 | From | Alan Stern <> | Subject | Re: Strange problem with USB device |
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On Tue, Jun 08, 2021 at 01:37:07PM -0500, Larry Finger wrote: > On 6/8/21 1:20 PM, Alan Stern wrote: > > 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.
I don't get it. If this is a PCIe device, why should it appear on a USB bus? Wouldn't you expect it to show up as a PCI device on a PCI bus instead?
> Is there some way to > add the usbcore debugging statement to the kernel options line at boot > time?
Yes. Use the kernel boot-line parameter:
usbcore.dyndbg="=p"
FYI, how to use dynamic debugging is explained at length in the kernel source file Documentation/admin-guide/dynamic-debug-howto.rst.
Alan Stern
> As I told GregKH, I am having the person with the problem try a rescue > system with a 5.12 kernel. > > Larry >
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