[CentOS] How to reset the USB subsystem?

Thu Jan 14 17:58:08 UTC 2021
Stephen John Smoogen <smooge at gmail.com>

On Thu, 14 Jan 2021 at 12:19, Fred <fred.fredex at gmail.com> wrote:

> from a non-expert (me):
> possibly figure out what happens when the device is plugged/unplugged and
> doing that by hand. if you can find the udev file(s) that manage the
> port(s) that get hung you may be able to figure out what those steps would
> be.
> or you could try, when hung, plugging it into a different USB port... some
> motherboards have multiple USB controllers, so even if one gets wedged
> tight, the other one(s) shouldn't be.
So what can happen is that the USB device is seeing a lot of noise from the
interface and shutdown the interface for a period of time. If you are
extremely lucky, it will even send some sort of message to the computer bus
it is doing this. In most other cases, the only fix is to reboot or
temporarily unplug the devices connected to that particular USB controller
(a computer may have multiple USB controllers since USB is a hubbed network
and collisions and conflicts are expected for short periods.). [It used to
be that you could cause a USB reset by removing the modules from the kernel
and add them but that was a long time ago when a PS/2 keyboard was a real
device and not an emulated PS/2 connected to the USB hub. ]

> Good Luck!
> Fred
> On Thu, Jan 14, 2021 at 11:22 AM Frank Bures <listfrank1 at gmail.com> wrote:
> > Hi,
> >
> > my USB connected printer goes into deep space from time to time probably
> > due to a HW problem on the MoBo.
> >
> > Is there a way how to reset the USB subsystem the same way one can
> restart
> > networking or X without the necessity to reboot?
> >
> > Thanks
> > Frank
> >
> > --
> >
> > <listfrank1 at gmail.com>
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Stephen J Smoogen.