[sane-devel] issue / fix in libsane-xerox_mfp for Samsung SCX-4200, sane-backends-1.0.24

[Dietmar Frohböse]

Dear all,

Please find some information and a patch for a multi function device (scanner printer).

issue: scanner is only discovered once after plug-in / power on

like this:

# SANE_DEBUG_XEROX_MFP=256  scanimage -d xerox_mfp:libusb:003:007 -v -v -v
[sanei_debug] Setting debug level of xerox_mfp to 256.
[xerox_mfp] sane_init: Xerox backend (build 13), version != null, authorize != null
[xerox_mfp] sane_xerox_mfp_open: 'libusb:003:007'
[xerox_mfp] sane_xerox_mfp_get_devices: (nil), 1
[xerox_mfp] list_one_device: libusb:003:010
[xerox_mfp] usb_dev_open: open 0x1d72170
[xerox_mfp] :: dev_command(INQUIRY[0x12], 70)
[xerox_mfp] [70] a8 00 43 10 53 41 4d 53 55 4e 47 20 4f 52 49 4f 4e 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 35 3f 04 29 00 00 27 d8 00 00 36 d8 00 01 2f 00 00 02 00 00 00 00 36 d8 00 00 36 d8 01 0d 05 05 00...
[xerox_mfp] dev_inquiry: found SAMSUNG/ORION
[xerox_mfp] usb_dev_close: closing dev 0x1d72170
scanimage: open of device xerox_mfp:libusb:003:007 failed: Invalid argument
Calling sane_exit
scanimage: finished

after this only an error occured

like this:

# SANE_DEBUG_XEROX_MFP=256  scanimage -d xerox_mfp:libusb:003:007 -v -v 
[sanei_debug] Setting debug level of xerox_mfp to 256.
[xerox_mfp] sane_init: Xerox backend (build 13), version != null, authorize != null
[xerox_mfp] sane_xerox_mfp_open: 'libusb:003:007'
[xerox_mfp] sane_xerox_mfp_get_devices: (nil), 1
[xerox_mfp] list_one_device: libusb:003:008
[xerox_mfp] usb_dev_open: open 0x1207170
[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 0x1207170
[xerox_mfp] list_one_device: dev_inquiry(libusb:003:008): Error during device I/O
scanimage: open of device xerox_mfp:libusb:003:007 failed: Invalid argument
Calling sane_exit
scanimage: finished


I've found several users faced this issue for Samsung SCX-... scanners 
(e. g. [sane-devel] Help needed diagnosing strange failure to scan with Samsung SCX-4500W)
and an useful hint what happens.
The call of sanei_usb_clear_halt (dev->dn); in xerox_mfp-usb.c has been introduced before.
To avoid this call solves the issue for me.

The message "open of device xerox_mfp:libusb:003:007 failed: Invalid argument" is not hindering to scan but
is also irritating. 

Best regards

Dietmar
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