[sane-devel] HP sane backend w/ HP Scanjet 6300C + ADF (USB) error

[Crypto]

Hi @ll,

I am new to this list and I am seeking help with a problem I would have 
thought has been fixed a long ago already.

I am using a HP Scanjet 6300C with ADF installed that I want to use to scan a 
lot of sheets. As the ADF does not offer duplex scanning it is required to 
scan frontside and then rearside of a double-sided document. To handle this 
conveniently I use gscan2pdf v. 0.9.27.

When beginning the scan job I can scan the front side of all sheets in the ADF 
with no error, then I store these front sides as a backup and want to 
continue scanning the rear sides.

Unfortunately, it happens that after the first amount of pages is scanned via 
ADF an error occurs stating

"unknown message scanadf: sane_read: Error during device I/O".

I seems to me that this is an error message of the hp sane backend and 
therefore does not have anything to do with gscan2pdf.

What happens is that the scanner's ADF engine is stuck in permanent running 
state after the scanner has successfuly scanned one page and would move to 
another sheet in the ADF. This can happen after scanning few sheets (6 pages) 
or 20 sheets.

To stop the scanner from making that engine noise and re-init it the only way 
is to unplug the USB connection to the scanner then replug it, after that the 
connection to the scanner is lost in gscan2pdf. There is another error 
message showing up:

"Unknown message: scanimage: sane_start: End of file reached" 

The error messages differ according to the interface (either scanadf or 
scanimage) that is used by gscan2pdf.

It has happend I get only one error message and can continue scanning. It has 
also happened that gscan2pdf closes altogether without offering to save any 
work.

What have I tried so far to fix things?

1.) The hp sane backend websites suggests to add a line "option dumb-read" in 
the hp.conf file, but this would only work if it were a SCSI scanner. The 
Scanjet 6300C IS a SCSI scanner, but I am using it with the USB interface 
only, and setting the option "dumb read" did not help. The scanner would move 
the ADF to the next sheet but then there was no scanning at all.

2.) Reboot Notebook, unplug USB connection, switch scanner off and on again.
I am not sure if this did anything, but as I wrote that on a clean boot-up I 
could scan all sheets in the ADF this seems to have some kind of influence, 
but I am not sure in which way.

I have browsed the web and noticed that this error seems to happen to many 
users of a HP scanner that is using the hp backend. They all used different 
kernel versions and had different hardware anyway, so I am somewhat sure that 
this cannot be the source of the error. It has got to be somewhere in how 
linux handles the USB ports and/or how the hp sane backend handles the 
scanner data streams.

The scanner is properly recognized on my system and, as i wrote above, it is 
working well for some time.

The scanner is recognized as a full speed USB device and the USB module that 
handles it is the ohci_hcd USB driver which should be sufficient for that. I 
have used usbview to see to which driver the scanner connects to.

kernel version is 2.6.27-7.slh.1-sidux-686 (32bit sidux linux ourea).
sane version is 1.0.14-7
sane-utils version is 1.0.9-23
libsane version is 1.0.9-23.

Thanks for any info shading some light on this.

Crypto.