[sane-devel] multiple, identical scanners?

[m. allan noah]

You might find that a kernel and/or a sane-backends upgrade will help
that problem. There have been usb improvements in both of those places
in the past year.

allan

On Wed, Nov 11, 2015 at 4:49 PM, Jeremy Chacon <chaco001 at umn.edu> wrote:
> Hi Johannes,
>
> Thanks for your very thorough response!
>
> It turned out you were correct, it was a USB issue. The scanners that always
> worked were connected to USB 2.0 ports, while the scanners that gave trouble
> were always connected to USB 3.0 ports (xhci_hcd when I did lsusb).
>
> Putting all the scanners on the older port type solved the problem.
>
> Thanks very much!
>
> Best,
>
> Jeremy
>
> On Wed, Nov 11, 2015 at 2:31 AM, Johannes Meixner <jsmeix at suse.de> wrote:
>>
>>
>> Hello,
>>
>> On Nov 10 14:09 Jeremy Chacon wrote (excerpt):
>>>
>>> ... sometimes gives an I/O Error ...
>>
>>
>> In general "sometimes I/O Error" indicates that the root
>> cause is somehow hardware related where "hardware" means
>> the actual computer hardware plus the computer's built-in
>> firmware (i.e. BIOS or UEFI) and "hardware related" means
>> computer hardware plus firmware plus Linux kernel driver
>> plus low-level hardware related software (e.g. libusb).
>> You may have a look at "a stack consisting of various
>> layers must be functional in its entirety" in
>> https://en.opensuse.org/SDB:Configuring_Scanners#Basics
>>
>> You did not tell how your scanners are connected to your
>> computer.
>>
>> If your scanners are connected via USB:
>>
>> There are currently issues with USB ports where the kernel
>> module "xhci" is used as kernel driver.
>> When "lsusb -t" shows "Driver=xhci_hcd" for the USB bus
>> and port where the USB scanner is connected (see "lsusb" where
>> the scanner is connected), then there could be issues depending
>> on the computer hardware and firmware.
>> In this case see
>> https://bugzilla.opensuse.org/show_bug.cgi?id=856794
>> in particular see
>> https://bugzilla.opensuse.org/show_bug.cgi?id=856794#c24
>> that reads (excerpt):
>> -----------------------------------------------------------------
>> My machine has 4 USB ports, two labeled with
>> the "super speed" USB logo (a.k.a. USB 3) and
>> two labeled with the normal USB logo (a.k.a. USB 2)
>> but for all 4 ports xhci is used and it fails on all 4 ports.
>> -----------------------------------------------------------------
>> and see
>> https://bugzilla.opensuse.org/show_bug.cgi?id=856794#c40
>>
>> When your scanner is not connected at a USB port where the
>> kernel module xhci_hcd is used as kernel driver (e.g. when
>> your scanner is connected at a USB port where the kernel
>> module uhci_hcd or ehci_hcd is used as kernel driver),
>> then have a look at "Trouble-Shooting (Debugging)" in
>> https://en.opensuse.org/SDB:Configuring_Scanners
>>
>> For example in your case to get USB debugging information
>> you could use comands (as root) like
>> -----------------------------------------------------------------
>> export SANE_DEBUG_SANEI_USB=128
>> scanimage -L
>> unset SANE_DEBUG_SANEI_USB
>> -----------------------------------------------------------------
>>
>>
>> Kind Regards
>> Johannes Meixner
>> --
>> SUSE LINUX GmbH - GF: Felix Imendoerffer, Jane Smithard,
>> Graham Norton - HRB 21284 (AG Nuernberg)
>>
>>
>> --
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>
>
>
>
> --
> ___________________________________________________________________________
>
> Jeremy M. Chacon, Ph.D.
>
> Post-Doctoral Associate, Harcombe Lab
> University of Minnesota
> Ecology, Evolution and Behavior
>
>
> --
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