[sane-devel] USB scanner slow, hopping back and forward

Fri Dec 9 13:29:31 UTC 2005

Hello,

I've got sane installed on a LinkSys NSLU2 embedded linux device running the OpenSlug Linux distribution (see http://www.nslu2-linux.org) for use with my Trust Direct WebScan 19200 scanner.

The scanner basically works, but scanning is slow due to the scanner hopping backwards quite often. E.g. basically it scans one centimeter, and then hops back half a centimeter. This happens when scanning A4-width at 300dpi. The higher the resolution, the smaller the steps get. 

I guess every now and then some data gets lost so the scanner has to rescan a line. When doing an 'export SANE_DEBUG_GT68XX=5', I see the following for about every 13th line (at 300dpi A4 width):

[gt68xx] sane_read: getting line 190 of 3531
[gt68xx] sane_read: getting line 191 of 3531
[gt68xx] sane_read: exit (line 192 of 3531, byte_count 1987 of 2563, 32768 bytes, 491520 total)
[gt68xx] sane_read: start (line 192 of 3531, byte_count 1987 of 2563)
[gt68xx] sane_read: getting line 192 of 3531

Does anybody know a solutions for this? Using the scanner on a regular PC running Windows, scans are smooth. Scanning is also smooth on the nslu2 when scanning at low resolutions (preview) or scanning only a small width. Could it be that the NSLU2 is too slow for handling the amount of data? I've also read something about different ohci-drivers, but I'm not sure whether that is applicable to my situation, and how to find/build/use another version.

Some system information: 
Linux version 2.6.12.2 (openslug at openslug.org) (gcc version 3.4.4) #1 Tue Sep 27 20:21:18 CDT 2005
scanimage (sane-backends) 1.0.15; backend version 1.0.15 (also tried 1.0.16 with latest gt68xx backend)
Scanner is currently connected through an USB hub, but also tried without it with same results.

>From /proc/cpuinfo:
Processor: XScale-IXP42x Family rev 1 (v5b)
BogoMIPS: 131.48

>From /proc/meminfo:
MemTotal: 30660 kB
MemFree: 6304 kB

>From /proc/bus/usb/devices: 
T:  Bus=01 Lev=02 Prnt=03 Port=02 Cnt=02 Dev#=  5 Spd=12  MxCh= 0
D:  Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=055f ProdID=021c Rev= 1.00
S:  Product=USB Scanner
C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=81(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms

lsusb:
Bus 003 Device 001: ID 0000:0000
Bus 002 Device 001: ID 0000:0000
Bus 001 Device 006: ID 03f0:6004 Hewlett-Packard DeskJet 5550
Bus 001 Device 005: ID 055f:021c Mustek Systems, Inc. BearPaw 1200 CU Plus
Bus 001 Device 004: ID 0840:0098 Argosy Research, Inc.
Bus 001 Device 003: ID 05e3:0605 Genesys Logic, Inc.
Bus 001 Device 002: ID 0781:5151 SanDisk Corp.
Bus 001 Device 001: ID 0000:0000

dmesg | egrep -i "usb|ehci|ohci"
usbcore: registered new driver usbfs
usbcore: registered new driver hub
ehci_hcd 0000:00:01.2: EHCI Host Controller
ehci_hcd 0000:00:01.2: new USB bus registered, assigned bus number 1
ehci_hcd 0000:00:01.2: irq 26, io mem 0x48002000
ehci_hcd 0000:00:01.2: park 0
ehci_hcd 0000:00:01.2: USB 2.0 initialized, EHCI 1.00, driver 10 Dec 2004
hub 1-0:1.0: USB hub found
ohci_hcd: 2004 Nov 08 USB 1.1 'Open' Host Controller (OHCI) Driver (PCI)
ohci_hcd 0000:00:01.0: OHCI Host Controller
ohci_hcd 0000:00:01.0: new USB bus registered, assigned bus number 2
ohci_hcd 0000:00:01.0: irq 28, io mem 0x48000000
hub 2-0:1.0: USB hub found
ohci_hcd 0000:00:01.1: OHCI Host Controller
ohci_hcd 0000:00:01.1: new USB bus registered, assigned bus number 3
ohci_hcd 0000:00:01.1: irq 27, io mem 0x48001000
hub 3-0:1.0: USB hub found
usb 1-1: new high speed USB device using ehci_hcd and address 2
Initializing USB Mass Storage driver...
usb 1-2: new high speed USB device using ehci_hcd and address 3
hub 1-2:1.0: USB hub found
scsi0 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 2
usb-storage: waiting for device to settle before scanning
usbcore: registered new driver usb-storage
USB Mass Storage support registered.
usb 1-2.1: new high speed USB device using ehci_hcd and address 4
scsi1 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 4
usb-storage: waiting for device to settle before scanning
usb 1-2.3: new full speed USB device using ehci_hcd and address 5
usb 1-2.4: new full speed USB device using ehci_hcd and address 6
usb-storage: device scan complete
usb-storage: device scan complete
drivers/usb/class/usblp.c: usblp0: USB Bidirectional printer dev 6 if 0 alt 0 proto 2 vid 0x03F0 pid 0x6004
usbcore: registered new driver usblp
drivers/usb/class/usblp.c: v0.13: USB Printer Device Class driver

With kind regards,
Ruud Senden.