[sane-devel] I/O Errors with hp 7400c

Johannes Meixner jsmeix at suse.de
Tue Nov 15 08:39:09 UTC 2016


On Nov 14 20:58 Olaf Meeuwissen wrote (excerpt):
> The mailing list archives have a number of posts on USB3 issues.

FYI: Only "lsusb -t" output shows what kernel driver is
actually used.

Regarding "USB 2" versus "USB 3" see

See also
in particular

Finally see
for possible workarounds by using an appropriate version
of the sane-backends software that may (hopefully) work
with your currently used "xhci_hcd" driver from your
currently installed kerenel.


If possible connect scanners at a traditional real "USB 2" port.

> If at all possible, use the device via USB2.0, by blacklisting
> the xhci kernel modules for example.

Usually it is not possible to use USB 3 hardware as if
it was USB 2 hardware (i.e. it is not possible to use
USB 3 hardware without the xhci kernel module), see

On nowadays computers there is often only USB 3 hardware
so that blacklisting the xhci kernel module would make
the whole USB no longer working which is in particular bad
when keyboard and mouse are connected via USB 3 hardware,
(have fun with un-blacklisting the xhci kernel module ;-).

One needs real traditional USB 2 hardware in the computer
to use a scanner device without the xhci kernel module.

As far as I know only few particular USB 3 capable chipsets
provide both real USB 3 hardware and real USB 2 hardware.

An ultimate way out:

Some users bought additional real USB 2 hardware for less
than 10 Euros to escape from the current USB 3 mess, see

I think about 10 Euros to get this issue out of sight
is an acceptable price compared to the currently still
ongoing annoyance with this issue (independent of when
the issue may get solved at some time in the future).

Kind Regards
Johannes Meixner
SUSE LINUX GmbH - GF: Felix Imendoerffer, Jane Smithard,
Graham Norton - HRB 21284 (AG Nuernberg)

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