[sane-devel] Accessing scanner through libusb fails with "invalid argument"

[Sebastian Reichelt]

Hello!

I have a Tevion MD9458 scanner which I would like to get to work with
Linux. Apparently it is supported by SANE, and sane-find-scanner detects
it correctly. However, when I try to access it with xsane or scanimage,
I get the message:

open of device gt68xx:libusb:002:... failed: Invalid argument

This happens when I am root or a normal user with appropriate
permissions. The right number increases every time I try this, as
somehow the file /proc/bus/usb/002/027 disappears and a new file
/proc/bus/usb/002/028 appears, and so on.

In syslog, there is also the message:
usbfs: USBDEVFS_CONTROL failed cmd scanimage rqt 192 rq 1 le n 64 ret
-84
And when I do an strace, there are a lot of lines that look like this:
ioctl(3, USBDEVFS_CONTROL, 0xbfffc790)  = 64

I'm using a 2.6.10 custom-built kernel and the current SANE and libusb
drivers from Debian testing (Debian version numbers are 1.0.15-6 for
libsane and 0.1.10-2 for libusb-0.1-4, whatever that means). USB works,
and I can also access a digital camera with libusb.

I hope this is enough information so you can help me with this problem.
Thanks in advance.

-- 
Sebastian Reichelt