Fixed problem with SCSI command queuing. Fixed problem that

resulted in black images on some Paragon 6000SP scanners. Added
option to disable backtracking. New version: 1.0-109.
Henning Meier-Geinitz <henning@meier-geinitz.de>

backend/mustek.conf

@@ -13,18 +13,21 @@ scsi MUSTEK * Scanner
 # option buffersize 1024         # set non standard buffer size (in kb)
 # option blocksize 2048          # set non standard block size (in kb)
 # option lineart-fix		 # lineart may be faster with this option off.
+# option disable-backtracking    # faster, but may produce stripes
 
 scsi SCANNER
 # option linedistance-fix        # stripes may go away in color mode
 # option buffersize 1024         # set non standard buffer size (in kb)
 # option blocksize 2048          # set non standard block size (in kb)
 # option lineart-fix		 # lineart may be faster with this option off.
+# option disable-backtracking    # faster, but may produce stripes
 
 /dev/scanner
 # option linedistance-fix        # stripes may go away in color mode
 # option buffersize 1024         # set non standard buffer size (in kb)
 # option blocksize 2048          # set non standard block size (in kb)
 # option lineart-fix		 # lineart may be faster with this option off.
+# option disable-backtracking    # faster, but may produce stripes
 
 #-------------------------- 600 II N ----------------------------------------
 #0x2eb

backend/mustek.desc

@@ -9,7 +9,7 @@
 ;
 
 :backend "mustek"		; name of backend
-:version "1.0-108"		; version of backend
+:version "1.0-109"		; version of backend
 :status :stable			; :alpha, :beta, :stable, :new
 :manpage "sane-mustek"		; name of manpage (if it exists)
 :url "http://www.meier-geinitz.de/sane/"

backend/mustek.h

@@ -87,6 +87,7 @@
 #define MUSTEK_FLAG_COVER_SENSOR (1 << 19) /* scanner can detect open cover */
 #define MUSTEK_FLAG_USE_BLOCK	 (1 << 20)  /* use blockmode */
 #define MUSTEK_FLAG_LEGAL_SIZE	 (1 << 21)  /* scanner has legal size */
+#define MUSTEK_FLAG_NO_BACKTRACK (1 << 21)  /* scanner has legal size */
 
 /* Source values: */
 #define MUSTEK_SOURCE_FLATBED	0

doc/sane-mustek.man

@@ -1,4 +1,4 @@
-.TH sane-mustek 5 "7 Jul 2001"
+.TH sane-mustek 5 "9 Jul 2001"
 .IX sane-mustek
 .SH NAME
 sane-mustek - SANE backend for Mustek flatbed scanners
@@ -123,6 +123,7 @@ The supported options are
 .BR blocksize ,
 .BR strip-height ,
 .BR disable-double-buffering ,
+.BR disable-backtracking ,
 and
 .B force-wait
 
@@ -187,6 +188,14 @@ the scanner. Try this option if you have trouble while scanning, e.g. SCSI
 errors, freezes, or the first few cm are repeated over and over again in your
 image.
 
+Option
+.B disable-backtracking
+is a positional option. If set, the scanner will not move back its slider
+after each SCSI buffer is filled (`backtracking´). Setting this option will
+lead to faster scans but may also produce horizontal stripes. This option
+doesn't work with every scanner (only some of the paragon models can modify
+backtracking).
+
 Finally,
 .B force-wait
 is a global option. If set, the backend will wait until the device is ready