[sane-devel] SCX-3405W scans with usb but not when shared from Linux Mint

[Ralph Little]

Hi,

On 2020-05-20 1:47 a.m., Olaf Meeuwissen wrote:
> Hi,
>
> I only see Ralph's part of the conversation on the list ...
>
That might be at least partly my fault. I may have used reply instead of 
reply-all at one time.

--
This is certainly a strange issue.
Perhaps I can summarise according to my understanding, and someone else 
might have some ideas.

The user has two machines:  a main machine connected via USB to a 
Samsung SCX-3405W and a network connect laptop.
Both machines are running some version of Linux Mint. I neglected to ask 
which version.
I believe that they are both running SANE 1.0.27.

The main machine can successfully print and scan using the direct USB 
connection.
The user wants to do network scanning from the laptop to the main 
machine using saned and the net backend.

As we left it, there seem to be two issues:

1) ***The laptop net backend does not appear to be reading config from 
its config file. ***
The user has listed the file /etc/sane.d/net.conf showing the main 
machine IP at the end.
Diag from the net backend shows that it does not pick this up.
However, the net backend can pick up the main machine IP in 
SANE_NET_HOSTS env variable, so was able to initiate a connection, but 
no scanners are reported.
The only thing I can think of is that the SANE installation on the 
laptop is broken and perhaps the net backend is not looking in 
/etc/sane.d for its config.
We did not pursue it further at that point, having managed to make a 
connection.

2) ***saned at the main machine fails to talk to the scanner, although 
it does detect it.***
Stopping the saned service on the main machine, and running saned 
manually as the user that can successfully scan, diag output revealed 
that the xerox_mfnp backend is having trouble talking to the scanner 
over USB when the laptop calls in through the net backend for a device list.

[xerox_mfp] usb_dev_open: open 0x5642a807f960
[xerox_mfp] :: dev_command(INQUIRY[0x12], 70)
[xerox_mfp] usb_dev_request: sanei_usb_read_bulk: Error during device I/O
[xerox_mfp] dev_command: dev_request: Error during device I/O
[xerox_mfp] usb_dev_close: closing dev 0x5642a807f960

My suggestion to the user is that perhaps the device is busy, possibly 
by a SANE application currently running on the main machine through USB 
and to check.

I am at a bit of a loss to understand what is happening here or how to 
proceed.

Cheers,
Ralph