Re: Forcing re-enumeration of a chosen USB device from userspace?

["Michał Pecio" <michal.pecio@gmail.com>]

> You can reset the device by using the usbreset program, which is part
> of the usbutils package.  Some distributions (such as Ubuntu) include
> it whereas others (such as Fedora) don't.  But if you don't have it,
> you can get the source code from https://github.com/gregkh/usbutils/
> and build it yourself.
> 
> If the reset causes some descriptors to change, the kernel will 
> re-enumerate the device.

Thanks for the suggestion. I compiled the tool fom Greg's repository
and ran it 100 times in a loop, but the descriptors remained unchanged.

I only got "reset USB device" messages in dmesg and class driver noise.


I had no luck playing with sysfs entries of the device, but I found
that the parent hub allows me to disable/enable individual ports. There
is some subtlely in USB 3.0 as the associated 2.0 port must be disabled
first to prevent downgrading to high speed, but it works.

Curiously though, it doesn't have the same effect as reloading the host
driver. My buggy device randomly comes back with good descriptors, with
the same bad descriptors, or most often it doesn't come back at all.

Regards,
Michal