Comment # 11 on bug 976813 from Johannes Meixner

FYI:

I asked on the SANE upstream sane-devel@lists.alioth.debian.org list
whether or not changing the installed sane-backends RPM package
could make a difference whether or not the third-party "epkowa" driver
works with the xhci_hcd kernel module.

See
http://lists.alioth.debian.org/pipermail/sane-devel/2016-April/034524.html
excerpt:
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Johannes Meixner writes:

> [...]
> Now I wonder if the "epkowa" backend could be also affected by the
> current sane-backends 1.0.25 "Workaround for USB3 problems in Linux
> kernel" that seems to no longer work with newest kernels, cf.
> http://lists.alioth.debian.org/pipermail/sane-devel/2016-January/034254.html
>
> In other words, I wonder if the "epkowa" backend uses the
> sane-backends USB code or if the "epkowa" backend implements USB
> communication on its own.

The epkowa backend uses its own *copy* of the sanei_usb code.  There was
a minor fix for USB 3.0 connected scanners in 2.30.1 (dated 2014-12-03).
That same fix was applied to sane-backends on 2014-12-10.

Please note that iscan does *not* actively track changes to the
sane-backends version of the sanei_usb code.  Also, iscan-2.30.1 is the
most recent version.

> In the end I like to understand if a version change of the installed
> sane-backends software on the user's computer could make a difference
> whether or not the "epkowa" backend works with the xhci_hcd kernel
> module.

That is rather unlikely but not impossible as it may depend on what
other backends do during their sane_init() and sane_get_devices().  If
all other backends are disabled, changing the version of the installed
sane-backends should not make a difference.  That is because the dll
backend doesn't do anything USB related itself.

Hope this helps,

Olaf Meeuwissen, LPIC-2       FLOSS Engineer -- EPSON AVASYS CORPORATION
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This means that in contrast to
https://bugzilla.opensuse.org/show_bug.cgi?id=975866#c2
where an upgrade to sane-backends version 1.0.25 made
the sane-backends driver "plustek" work with xhci_hcd
it is rather unlikely that another sane-backends version
makes the third-party "epkowa" driver work with xhci_hcd.

The only way - as far as I understand it - how a different
sane-backends version could even make the "epkowa" driver
work with xhci_hcd is when sane-backends drivers are also
enabled in /etc/sane.d/dll.conf - for example either the
sane-backends driver epson or alternatively epson2.

But this is basically only blind guess.

In the end when there are issues with third-party drivers
nobody - except the authors of the third-party software - can provide
real help and support because nobody - except the authors - know how
their software really works.

In this case you can only contact those wherefrom you got the
third-party software for any kind of real help and support.

See "Third-Party Scanner Drivers" in
https://en.opensuse.org/SDB:Configuring_Scanners