Using an external USB 3.5-inch floppy disk drive in Linux

Back in 2004 I needed to get some files off my old 3.5″ floppy disks, so I bought an external USB floppy disk drive to use with a laptop running Windows XP. The label on the drive gives the manufacturer and model as ‘SmartDisk: FDUSB-TM2, Mitsumi Model #: D353FUE’.

Anyway, today I wanted to throw out some 720KB DD (Double Density) and 1440KB HD (High Density) 3.5″ floppy disks but first needed to check their contents and wipe them. So I dug out the SmartDisk USB drive to see if it would work with the current Gentoo Linux installation on my newest laptop. I was pleased to discover that it does, and below are some notes on how to use it in case anyone else needs to use one of these devices.

Once plugged in to a USB port on my laptop, the lsusb command shows the device has been recognised:

Bus 001 Device 013: ID 03ee:6901 Mitsumi SmartDisk FDD

Note that the Linux floppy driver is not needed for USB floppy disk drives:

root # grep -i CONFIG_BLK_DEV_FD /usr/src/linux/.config
# CONFIG_BLK_DEV_FD is not set

A Linux utility named ufiformat is used to low-level format floppy disks in USB floppy disk drives. A Gentoo Linux ebuild for Version 0.9.9 of ufiformat is listed below, and it can be used in a local overlay under the category sys-fs:

# Copyright 1999-2014 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2
# $Header: $

EAPI=5

DESCRIPTION="USB Floppy Disk formatting tool"
HOMEPAGE="http://www.geocities.jp/tedi_world/format_usbfdd_e.html"
SRC_URI="http://www.geocities.jp/tedi_world/${P}.tar.gz"

LICENSE="GPL-2"
SLOT="0"
KEYWORDS="~amd64 ~x86"
IUSE=""

RDEPEND="sys-fs/e2fsprogs"
DEPEND=${RDEPEND}

The ufiformat utility is straightforward to use:

root # ufiformat --help
Usage: ufiformat [OPTION]... [DEVICE]
Format a floppy disk in a USB floppy disk DEVICE.

  -f, --format [SIZE]  specify format capacity SIZE in KB
                       without -f option, the format of the current media will be used
  -V, --verify         verify the medium after formatting
  -F, --force          do not perform any safety checks
  -i, --inquire        show device information, instead of performing format
                       without DEVICE argument, list USB floppy disk devices
  -v, --verbose        show detailed output
  -q, --quiet          suppress minor output
  -h, --help           show this message

To find the device name, use the blkid command before plugging in the USB cable and again after plugging in the USB cable. The extra device listed the second time will be the floppy disk drive. For example, in my case the new line at the end of the blkid output indicated the drive was /dev/sdd:

/dev/sdd: SEC_TYPE="msdos" UUID="BBBA-37AF" TYPE="vfat"

The fdisk command will confirm that the device is the floppy drive:

root # fdisk -l /dev/sdd
Disk /dev/sdd: 720 KiB, 737280 bytes, 1440 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Note that /dev/sdd will not be listed in the output of blkid if there is no disk in the floppy drive, although the ls command will list /dev/sdd while the drive is connected to the computer.

Notice that there are no devices /dev/fd0, /dev/fd1, /dev/fd2 and /dev/fd3, etc. This does not matter.

root # ls /dev
audio1           dri      i2c-10   kmem          mapper              nvidiactl  sda1       sequencer2  tty0   tty2   tty30  tty41  tty52  tty63    usbmon3     vcs2    vcsa12
autofs           dsp1     i2c-11   kmsg          mcelog              nvram      sda2       sg0         tty1   tty20  tty31  tty42  tty53  tty7     usbmon4     vcs3    vcsa2
block            fb0      i2c-2    log           mem                 pktcdvd    sda3       sg1         tty10  tty21  tty32  tty43  tty54  tty8     v4l         vcs4    vcsa3
bsg              fd       i2c-3    loop-control  memory_bandwidth    port       sda5       sg2         tty11  tty22  tty33  tty44  tty55  tty9     vboxdrv     vcs5    vcsa4
bus              full     i2c-4    loop0         mixer               ptmx       sda6       sg3         tty12  tty23  tty34  tty45  tty56  ttyS0    vboxdrvu    vcs6    vcsa5
char             fuse     i2c-5    loop1         mixer1              pts        sda7       shm         tty13  tty24  tty35  tty46  tty57  ttyS1    vboxnetctl  vcs7    vcsa6
console          hidraw0  i2c-6    loop2         mqueue              random     sdb        snapshot    tty14  tty25  tty36  tty47  tty58  ttyS2    vboxusb     vcs8    vcsa7
core             hidraw1  i2c-7    loop3         network_latency     rfkill     sdb1       snd         tty15  tty26  tty37  tty48  tty59  ttyS3    vcs         vcs9    vcsa8
cpu              hidraw2  i2c-8    loop4         network_throughput  root       sdc        stderr      tty16  tty27  tty38  tty49  tty6   urandom  vcs1        vcsa    vcsa9
cpu_dma_latency  hpet     i2c-9    loop5         null                rtc        sdc1       stdin       tty17  tty28  tty39  tty5   tty60  usbmon0  vcs10       vcsa1   vga_arbiter
cuse             i2c-0    initctl  loop6         nvidia-modeset      rtc0       sdd        stdout      tty18  tty29  tty4   tty50  tty61  usbmon1  vcs11       vcsa10  video0
disk             i2c-1    input    loop7         nvidia0             sda        sequencer  tty         tty19  tty3   tty40  tty51  tty62  usbmon2  vcs12       vcsa11  zero
root # ls -la /dev/fd
lrwxrwxrwx 1 root root 13 Jan 17 02:13 /dev/fd -> /proc/self/fd
root # ls -la /proc/self/fd
total 0
dr-x------ 2 root root  0 Jan 17 04:26 .
dr-xr-xr-x 8 root root  0 Jan 17 04:26 ..
lrwx------ 1 root root 64 Jan 17 04:26 0 -> /dev/pts/1
lrwx------ 1 root root 64 Jan 17 04:26 1 -> /dev/pts/1
lrwx------ 1 root root 64 Jan 17 04:26 2 -> /dev/pts/1
lr-x------ 1 root root 64 Jan 17 04:26 3 -> /proc/17669/fd

To format an HD floppy disk with the FAT file system, I did the following:

root # ufiformat -f 1440 /dev/sdd
geometry: track=80, head=2, sector=18, block=512
done                                   
root # /usr/sbin/mkfs.vfat /dev/sdd
mkfs.fat 4.0 (2016-05-06)
attribute "partition" not found
root # ufiformat -i /dev/sdd
vendor:  MITSUMI
product: USB FDD
write protect: off
media type: 2HD
status      block size   kb
formatted    2880  512 1440
formattable  2880  512 1440
formattable  1232 1024 1232
formattable  2400  512 1200

To format a DD floppy disk with the FAT file system, I did the following:

root # ufiformat -f 720 /dev/sdd
geometry: track=80, head=2, sector=9, block=512
done                                   
root # /usr/sbin/mkfs.vfat /dev/sdd
mkfs.fat 4.0 (2016-05-06)
attribute "partition" not found
root # ufiformat -i /dev/sdd
vendor:  MITSUMI
product: USB FDD
write protect: off
media type: 2DD
status      block size   kb
formatted    1440  512  720
formattable  1440  512  720

I use the KDE Desktop Environment. The Device Notifier widget in the System Tray shows the drive and — once a formatted floppy disk is in the drive — it is possible to use the Device Notifier to mount, open and unmount the floppy disk. However, it is also possible to use the command line:

root # mkdir /mnt/floppy
root # mount /dev/sdd /mnt/floppy
root # ls /mnt/floppy
root # cp /test.txt /mnt/floppy/
root # ls /mnt/floppy
test.txt
root # umount /dev/sdd

Earlier in this post I showed examples of formatting floppy disks using the FAT file system, but it is of course possible to format them using other file systems, such as:

root # mkfs.ext2 /dev/sdd
mke2fs 1.43.3 (04-Sep-2016)
/dev/sdd contains a vfat file system
Proceed anyway? (y,n) y
Creating filesystem with 720 1k blocks and 96 inodes

Allocating group tables: done                            
Writing inode tables: done                            
Writing superblocks and filesystem accounting information: done

Anyway, I was able to check the contents of the floppies and wipe them before disposing of them. It’s good to know that some old technologies can still be used when needs be. I won’t be throwing out the old floppy disk drive just yet.

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Stopping my laptop spontaneously resuming immediately after Suspend to RAM

If I selected ‘Suspend to RAM’ via the Desktop Environment in the Gentoo Linux installation on my Clevo W230SS laptop, the laptop did suspend but then immediately resumed automatically. The same thing happened if I suspended the laptop using either of the following commands from the command line:

root # pm-suspend

user $ qdbus org.kde.Solid.PowerManagement /org/freedesktop/PowerManagement Suspend

This behaviour was annoying, as it meant I had to shut down the laptop completely when I was not at my desk for a long time, rather than just being able to suspend the laptop.

Problem 1: USB devices

I usually have several USB devices connected to my laptop when I am at home or in the office, and I began to suspect that these USB connections were somehow causing Linux to resume as soon as it had suspended. Searching the Web turned up a Q&A page that seemed to confirm my suspicion: Why does my laptop resume immediately after suspend? I installed the utility acpitool mentioned on that Web page and used it with the ‘-w‘ option to check which wakeup-capable USB devices were currently enabled in my installation:

root # acpitool -w
   Device       S-state   Status   Sysfs node
  ---------------------------------------
  1. RP01         S4    *disabled  pci:0000:00:1c.0
  2. PXSX         S4    *disabled
  3. RP02         S4    *disabled
  4. PXSX         S4    *disabled
  5. RP03         S4    *disabled  pci:0000:00:1c.2
  6. PXSX         S4    *disabled  pci:0000:03:00.0
  7. RP04         S4    *disabled  pci:0000:00:1c.3
  8. PXSX         S4    *disabled  pci:0000:04:00.0
  9.            *disabled  platform:rtsx_pci_sdmmc.0
  10.           *disabled  platform:rtsx_pci_ms.0
  11. RLAN        S4    *disabled
  12. RP05        S4    *disabled
  13. PXSX        S4    *disabled
  14. RP06        S4    *disabled
  15. PXSX        S4    *disabled
  16. RP07        S4    *disabled
  17. PXSX        S4    *disabled
  18. RP08        S4    *disabled
  19. PXSX        S4    *disabled
  20. GLAN        S4    *disabled
  21. EHC1        S3    *enabled   pci:0000:00:1d.0
  22. EHC2        S3    *enabled   pci:0000:00:1a.0
  23. XHC         S3    *disabled  pci:0000:00:14.0
  24. HDEF        S4    *disabled  pci:0000:00:1b.0
  25. PEG0        S4    *disabled  pci:0000:00:01.0
  26. PEGP        S4    *disabled  pci:0000:01:00.0
  27. PEGA        S4    *disabled
  28. PWRB        S3    *enabled   platform:PNP0C0C:0
^C
root #

(I had to use Ctrl-C to get back to the command prompt.)

I then used the command ‘acpitool -W <device number>‘ on each of the three enabled devices (21, 22 and 28 above) in order to find out which of them needed to be disabled in order for my laptop to remain suspended when I suspended it. I found that I only needed to disable devices EHC1 (pci:0000:00:1d.0) and EHC2 (pci:0000:00:1a.0) to be able to suspend the laptop successfully:

root # acpitool -W 21 | grep 21
  Changed status for wakeup device #21 (EHC1)
  21. EHC1        S3    *disabled  pci:0000:00:1d.0
^C
root # acpitool -W 22 | grep 22
  Changed status for wakeup device #22 (EHC2)
  22. EHC2        S3    *disabled  pci:0000:00:1a.0
^C
root # pm-suspend

In this laptop these two devices are two internal USB root hubs:

user $ lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
        |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 4, If 0, Class=Mass Storage, Driver=usb-storage, 480M
            |__ Port 3: Dev 5, If 0, Class=Mass Storage, Driver=usb-storage, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M
        |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 6, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 4: Dev 7, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 4: Dev 7, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 4, If 0, Class=Wireless, Driver=btusb, 12M
        |__ Port 3: Dev 4, If 1, Class=Wireless, Driver=btusb, 12M
        |__ Port 4: Dev 5, If 0, Class=Video, Driver=uvcvideo, 480M
        |__ Port 4: Dev 5, If 1, Class=Video, Driver=uvcvideo, 480M

The next challenge was to find out how to disable and re-enable the two devices automatically when I suspend and resume the installation. Further searching of the Web turned up another Q&A page which pointed me in the right direction: How to run a script when suspending/resuming?. It turns out that you need to put a script of the following form in the directory /etc/pm/sleep.d/:

#!/bin/bash

case "$1" in
    suspend)
        # executed on suspend
        ;;
    resume) 
        # executed on resume
        ;;
    *)
        ;;
esac

If you want the script to run when hibernating and thawing, the tests would be for ‘hibernate‘ and ‘thaw‘ instead of ‘suspend‘ and ‘resume‘.

The thread [SOLVED] Computer immediately resumes after suspend in the KDE Forums almost gave me the solution I needed. I created a file /etc/pm/sleep.d/01-toggle-usb-hubs containing the following:

#!/bin/sh
#
username=fitzcarraldo
userhome=/home/$username
export XAUTHORITY="$userhome/.Xauthority"
export DISPLAY=":0"
#
case "$1" in
    suspend|hibernate)
        # Unbind ehci-pci for the device 0000:00:1a.0
        echo -n "0000:00:1a.0" | tee /sys/bus/pci/drivers/ehci-pci/unbind
        # Unbind ehci-pci for the device 0000:00:1d.0
        echo -n "0000:00:1d.0" | tee /sys/bus/pci/drivers/ehci-pci/unbind
    ;;
    resume|thaw)
        # Bind ehci-pci for the device 0000:00:1a.0
        echo -n "0000:00:1a.0" | tee /sys/bus/pci/drivers/ehci-pci/bind
        # Bind ehci-pci for the device 0000:00:1d.0
        echo -n "0000:00:1d.0" | tee /sys/bus/pci/drivers/ehci-pci/bind
    ;;
    *)
        exit $NA
    ;;
esac

I obtained the device details from the output of the ‘acpitools -w‘ command listed earlier and by looking in the directory /sys/bus/pci/drivers/ehci-pci:

root # ls /sys/bus/pci/drivers/ehci-pci
0000:00:1a.0  0000:00:1d.0  bind  new_id  remove_id  uevent  unbind

Notice that the script tests for either ‘suspend‘ or ‘hibernate‘ to disable the two devices, and tests for either ‘resume‘ or ‘thaw‘ to enable the two devices.

I made the script executable:

root # chmod +x /etc/pm/sleep.d/01-toggle-usb-hubs


Problem 2: Blank X Windows display due to NVIDIA closed-source driver bug

However, a problem remained: My laptop has an NVIDIA GPU and, when resuming from suspension, the X Windows display (Virtual Terminal 7) was a blank screen with only the mouse pointer visible. Now, it so happens that I also experience this behaviour if I switch from Virtual Terminal 7 to e.g. Virtual Terminal 1 (Ctrl-Alt-F1) and then switch back to Virtual Terminal 7 (Ctrl-Alt-F7). Apparently this is due to a bug in the closed-source NVIDIA driver (I am currently using Gentoo package x11-drivers/nvidia-drivers-358.16-r1). However, if I first disable compositing before switching to another virtual terminal, the X Windows display on Virtual Terminal 7 is still visible when I switch back to Virtual Terminal 7. It turns out there is a known bug in the NVIDIA closed-source driver, as explained in the following KDE bug report and thread in the NVIDIA CUDA ZONE Forums:

KDE Bugtracking System Bug No. 344326 – Black or corrupted screen on resume from suspend

NVIDIA CUDA ZONE Forums – Black screen on resume from suspend with 325.15 and KWin 4.11 with enabled compositing

As the suggested work-around is to disable compositing before suspending to RAM, I created a script /etc/pm/sleep.d/02-toggle-compositing containing the following:

#!/bin/sh
#
username=fitzcarraldo
userhome=/home/$username
export XAUTHORITY="$userhome/.Xauthority"
export DISPLAY=":0"
#
case "$1" in
    suspend|hibernate)
        su $username -c "qdbus org.kde.kwin /KWin toggleCompositing" &
    ;;
    resume|thaw)
        su $username -c "qdbus org.kde.kwin /KWin toggleCompositing" &
    ;;
    *)
        exit $NA
    ;;
esac

As I have KDE 4 on this laptop, I made the script use the command ‘qdbus org.kde.kwin /KWin toggleCompositing‘ to disable/enable compositing, so replace that command with the appropriate command if you are not using KDE 4.

I made the script executable:

root # chmod +x /etc/pm/sleep.d/02-toggle-compositing

Now both the scripts in the directory /etc/pm/sleep.d/ run when I suspend or resume the laptop, and everything works as expected. Mission accomplished! πŸ™‚

The problem of scanning using USB multi-function printers in Linux (success at last)

After my investigations described in a couple of earlier posts ([1], [2]), I finally got Gentoo Linux to scan reliably via the USB connection to my Canon MP560 MFP (multi-function peripheral), a single USB device with three interfaces: scanner (Interface 0); printer (Interface 1); mass storage (Interface 2). Well, ninety-nine per cent reliably, if that isn’t a contradiction in terms. The formula for success? I had to do all the following:

  1. Stop the kernel from binding the usb-storage driver to the device.

  2. Create a UDEV rule to modify the ACL (access control list) of the device to give both the ‘lp‘ and ‘scanner‘ groups Read-Write access to the device.

  3. Create a UDEV rule to: a) change the owner of the device from ‘root‘ to my user account (fitzcarraldo); b) change the device’s group to ‘scanner‘ instead of ‘lp‘; c) give all users Read-Write access to the device (see my note about this at the end of this post).

  4. Disable the SANE backend from accessing the MP560 via the network.

Let’s look in more detail at each of these …

Stop the kernel from binding the usb-storage driver to the device

Originally I had built the usb-storage driver into the kernel (CONFIG_USB_STORAGE=y). During the course of my investigations into this problem I rebuilt the kernel with CONFIG_USB_STORAGE=m, i.e. I rebuilt the driver as an external module, although it should not matter either way.

The vendor ID (04a9) and product ID (173e) of the MP560 can be found using the lsusb command:

# lsusb | grep -i canon
Bus 001 Device 007: ID 04a9:173e Canon, Inc. MP560

If the usb-storage driver is built as an external module, the kernel configuration file will include the following:

# grep CONFIG_USB_STORAGE= /usr/src/linux/.config
CONFIG_USB_STORAGE=m

In this case, it is possible to stop the driver binding to the USB storage interface in the MP560 by creating a ‘quirk’ in the file /etc/modprobe.d/usb-storage.conf as shown below:

# cat /etc/modprobe.d/usb-storage.conf
options usb-storage quirks=04a9:173e:i

If the usb-storage driver is built into the kernel, the kernel configuration file will include the following:

# grep CONFIG_USB_STORAGE= /usr/src/linux/.config
CONFIG_USB_STORAGE=y

In this case, it is possible to stop the driver binding to the USB storage interface in the MP560 by adding a ‘quirk’ (usb-storage.quirks=<idVendor>:<idProduct>:i) to the kernel boot line as shown below (ignore the rest of the parameters shown below, as yours are likely to be different):

# grep usb-storage /boot/grub/grub.cfg
linux /vmlinuz-3.18.11-gentoo root=/dev/sda5 ro drm_kms_helper.edid_firmware=edid/1920x1080_Clevo_W230SS.bin i915.modeset=1 rcutree.rcu_idle_gp_delay=1 usb-storage.quirks=04a9:173e:i

If you edit the file /boot/grub/grub.cfg directly, the change will be lost if you rebuild or upgrade in future. The ‘proper’ way to add the quirk would be to add it to the list of kernel boot parameters in GRUB_CMDLINE_LINUX_DEFAULT in the file /etc/default/grub and regenerate grub.cfg using the command ‘grub2-mkconfig -o /boot/grub/grub.cfg‘.

Create a UDEV rules file to modify the device’s ACL

I created a UDEV rules file /etc/udev/rules.d/99-canon-mp560.rules containing the following:

# ACL settings for Canon PIXMA MP560 printer MFP
ATTR{idVendor}=="04a9", ATTR{idProduct}=="173e", GOTO="canon"
GOTO="canon_end"
 
LABEL="canon"
RUN+="/bin/setfacl -m g:scanner:rw -m g:lp:rw $env{DEVNAME}"
TEST=="/var/run/ConsoleKit/database", \
        RUN+="udev-acl --action=$env{ACTION} --device=$env{DEVNAME}"
 
LABEL="canon_end"

Create a UDEV rules file to change the owner, group and permissions of the device

The file 41-libsane.rules in my installation is the only UDEV rules file in the directory /lib/udev/rules.d/ that explicitly mentions the MP560:

# grep 173e /lib/udev/rules.d/*
/lib/udev/rules.d/41-libsane.rules:ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

As the USB device was always in the ‘lp‘ group (see the output of the ‘ls -la‘ command [1]), the above UDEV rule was clearly being overridden by another rule, but which one in the long list of rules files created automatically when I installed the OS and various packages (see below)?

# ls -F1 /lib/udev/rules.d/
10-ft-rockey.rules
10-virtualbox.rules
40-gentoo.rules
40-usb-media-players.rules
41-libsane.rules
42-usb-hid-pm.rules
50-udev-default.rules
56-hpmud.rules
60-block.rules
60-cdrom_id.rules
60-drm.rules
60-evdev.rules
60-persistent-alsa.rules
60-persistent-input.rules
60-persistent-storage-tape.rules
60-persistent-storage.rules
60-persistent-v4l.rules
60-serial.rules
61-accelerometer.rules
64-btrfs.rules
69-cd-sensors.rules
70-libgphoto2.rules
70-mouse.rules
70-printers.rules
70-touchpad.rules
70-udev-acl.rules
75-net-description.rules
75-probe_mtd.rules
77-mm-cinterion-port-types.rules
77-mm-ericsson-mbm.rules
77-mm-huawei-net-port-types.rules
77-mm-longcheer-port-types.rules
77-mm-mtk-port-types.rules
77-mm-nokia-port-types.rules
77-mm-pcmcia-device-blacklist.rules
77-mm-platform-serial-whitelist.rules
77-mm-simtech-port-types.rules
77-mm-telit-port-types.rules
77-mm-usb-device-blacklist.rules
77-mm-usb-serial-adapters-greylist.rules
77-mm-x22x-port-types.rules
77-mm-zte-port-types.rules
77-nm-olpc-mesh.rules
78-sound-card.rules
80-drivers.rules
80-mm-candidate.rules
80-net-name-slot.rules
80-udisks2.rules
85-regulatory.rules
90-alsa-restore.rules
90-libgpod.rules
90-network.rules
90-pulseaudio.rules
95-cd-devices.rules
95-upower-battery-recall-dell.rules
95-upower-battery-recall-fujitsu.rules
95-upower-battery-recall-gateway.rules
95-upower-battery-recall-ibm.rules
95-upower-battery-recall-lenovo.rules
95-upower-battery-recall-toshiba.rules
95-upower-csr.rules
95-upower-hid.rules
95-upower-wup.rules
97-hid2hci.rules
99-fuse.rules
99-ntfs3g.rules
99-nvidia.rules

Anyway, I created a UDEV rules file /etc/udev/rules.d/95-libsane.rules to change the owner of the MP560 USB device from ‘root‘ to me (i.e. user name ‘fitzcarraldo‘), to put the device in the ‘scanner‘ group instead of the ‘lp‘ group, and to give all users Read-Write permission for the device:

ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0666", OWNER="fitzcarraldo", GROUP="scanner", ENV{libsane_matched}="yes"

So I now have two user-created UDEV rules files:

# ls /etc/udev/rules.d/
95-libsane.rules 99-canon-mp560.rules

Note that user-created UDEV rules files should be put in the directory /etc/udev/rules.d/, not the directory /lib/udev/rules.d/ which is reserved for UDEV rules installed when you install the OS and by packages you install later. Unfortunately, there is no consistency in UDEV rules file names and their contents between Linux distributions, which makes debugging UDEV rules even more difficult. Higher numbered rules files override lower-numbered rules files.

I then switched off the MP560 and switched it on again. The two UDEV rules files I created had worked as intended. The ownership and group of the device had changed, and so had the permissions and ACL:

# ls -la /dev/bus/usb/001
total 0
drwxr-xr-x  2 root         root       200 Jul 29 10:10 .
drwxr-xr-x  4 root         root        80 Jul 29 09:56 ..
crw-rw-r--  1 root         usb     189, 0 Jul 29 11:25 001
crw-rw-r--  1 root         usb     189, 1 Jul 29 09:56 002
crw-rw-r--  1 root         usb     189, 2 Jul 29 11:25 003
crw-rw-r--  1 root         usb     189, 3 Jul 29 09:56 004
crw-rw-r--  1 root         usb     189, 4 Jul 29 11:25 005
crw-rw-r--  1 root         usb     189, 5 Jul 29 11:25 006
crw-rw-r--  1 root         usb     189, 7 Jul 29 11:25 008
crw-rw-rw-+ 1 fitzcarraldo scanner 189, 8 Jul 29 11:27 009

# getfacl /dev/bus/usb/001/009
getfacl: Removing leading '/' from absolute path names
# file: dev/bus/usb/001/009
# owner: fitzcarraldo
# group: scanner
user::rw-
user:fitzcarraldo:rw-
group::rw-
group:lp:rw-
group:scanner:rw-
mask::rw-
other::rw-

Disable the SANE backend from accessing the MP560 via the network

Although scanning via the USB connection sometimes still works if I have also specified a network connection in the file /etc/sane.d/pixma.conf, apparently the two interfaces should not normally be enabled simultaneously. See the post [sane-devel] Pixma 530 series – tested and not working by SANE developer Rolf Bensch:

Please disconnect the scanner from network and try again. The backend
has problems if both network and USB are connected at once.

Therefore, to try using SANE to access the MP560 via USB, I disabled network access to the MP560 by commenting out the URI in the relevant SANE backend configuration file, which in the case of the MP560 is the file /etc/sane.d/pixma.conf. I commented out the line ‘bjnp://192.168.1.78‘ which I had previously inserted to enable me to scan via my home network because the USB connection was unreliable.

Trying to scan

I then checked if the USB-connected scanner is detected by SANE when running as root user and when running under my user account:

# scanimage -L
device `pixma:04A9173E_1653C4' is a CANON Canon PIXMA MP560 multi-function peripheral
# sane-find-scanner -q
found USB scanner (vendor=0x04a9 [Canon], product=0x173e [MP560 series]) at libusb:001:010
# exit
exit
$ scanimage -L
device `pixma:04A9173E_1653C4' is a CANON Canon PIXMA MP560 multi-function peripheral
$ sane-find-scanner -q
found USB scanner (vendor=0x04a9 [Canon], product=0x173e [MP560 series]) at libusb:001:010

The test using the scanimage command worked:

$ scanimage -d pixma:04A9173E_1653C4 -T
scanimage: scanning image of size 638x877 pixels at 24 bits/pixel
scanimage: acquiring RGB frame, 8 bits/sample
scanimage: reading one scanline, 1914 bytes...  PASS
scanimage: reading one byte...          PASS
scanimage: stepped read, 2 bytes...     PASS
scanimage: stepped read, 4 bytes...     PASS
scanimage: stepped read, 8 bytes...     PASS
scanimage: stepped read, 16 bytes...    PASS
scanimage: stepped read, 32 bytes...    PASS
scanimage: stepped read, 64 bytes...    PASS
scanimage: stepped read, 128 bytes...   PASS
scanimage: stepped read, 256 bytes...   PASS
scanimage: stepped read, 512 bytes...   PASS
scanimage: stepped read, 1024 bytes...  PASS
scanimage: stepped read, 2048 bytes...  PASS
scanimage: stepped read, 2047 bytes...  PASS
scanimage: stepped read, 1023 bytes...  PASS
scanimage: stepped read, 511 bytes...   PASS
scanimage: stepped read, 255 bytes...   PASS
scanimage: stepped read, 127 bytes...   PASS
scanimage: stepped read, 63 bytes...    PASS
scanimage: stepped read, 31 bytes...    PASS
scanimage: stepped read, 15 bytes...    PASS
scanimage: stepped read, 7 bytes...     PASS
scanimage: stepped read, 3 bytes...     PASS

So I tried to scan an A4 page from the command line:

$ scanimage -d pixma:04A9173E_1653C4 -l 0 -t 0 -x 215 -y 297 --resolution 150 --mode Color | convert - scanned-page.png

That worked, so I launched XSane, one of the GUI scanner applications:

$ xsane

That also worked.

Sometimes either scanimage or a GUI scanner application (XSane, gscan2pdf, Simple Scan or whatever) hangs, but, more often than not, scanning now works via the USB connection. However, if either scanimage or a GUI scanner application hangs, I kill them, run them again and then they usually work.

Importantly, printing still works, even though I have changed the USB device group from ‘lp‘ to ‘scanner‘.

So I have satisfied my curiosity and managed to get the MP560 to scan when connected to my laptop via USB, even though it already worked fine when using a network connection instead.

A note on the version of SANE

For information, I currently have Version 1.0.25_pre20150725 (daily snapshot from 25 July 2015) of the package sane-backends installed:

$ eix -I sane-backends
[I] media-gfx/sane-backends
     Available versions:  1.0.24-r5 (~)1.0.25_pre20150628 (~)1.0.25_pre20150725[1] {avahi doc gphoto2 ipv6 snmp systemd threads usb v4l xinetd ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32" SANE_BACKENDS="+abaton +agfafocus +apple +artec +artec_eplus48u +as6e +avision +bh +canon +canon630u +canon_dr -canon_pp +cardscan +coolscan +coolscan2 +coolscan3 +dc210 +dc240 +dc25 +dell1600n_net +dmc +epjitsu +epson +epson2 +fujitsu +genesys +gt68xx +hp +hp3500 +hp3900 +hp4200 +hp5400 +hp5590 +hpljm1005 -hpsj5s +hs2p +ibm +kodak +kodakaio +kvs1025 +kvs20xx kvs40xx +leo +lexmark +ma1509 +magicolor +matsushita +microtek +microtek2 +mustek -mustek_pp +mustek_usb mustek_usb2 +nec +net +niash +p5 +pie +pixma +plustek +plustek_pp -pnm +qcam +ricoh +rts8891 +s9036 +sceptre +sharp +sm3600 +sm3840 +snapscan +sp15c +st400 +stv680 +tamarack +teco1 +teco2 +teco3 +test +u12 +umax +umax1220u +umax_pp +xerox_mfp"}
     Installed versions:  1.0.25_pre20150725[1](01:39:24 25/07/15)(avahi gphoto2 ipv6 usb v4l -doc -snmp -systemd -threads -xinetd ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="32 64 -x32" SANE_BACKENDS="abaton agfafocus apple artec artec_eplus48u as6e avision bh canon canon630u canon_dr cardscan coolscan coolscan2 coolscan3 dc210 dc240 dc25 dell1600n_net dmc epjitsu epson epson2 fujitsu genesys gt68xx hp hp3500 hp3900 hp4200 hp5400 hp5590 hpljm1005 hs2p ibm kodak kodakaio kvs1025 kvs20xx leo lexmark ma1509 magicolor matsushita microtek microtek2 mustek mustek_usb nec net niash p5 pie pixma plustek plustek_pp qcam ricoh rts8891 s9036 sceptre sharp sm3600 sm3840 snapscan sp15c st400 stv680 tamarack teco1 teco2 teco3 test u12 umax umax1220u umax_pp xerox_mfp -canon_pp -hpsj5s -kvs40xx -mustek_pp -mustek_usb2 -pnm")
     Homepage:            http://www.sane-project.org/
     Description:         Scanner Access Now Easy - Backends

[1] "local_overlay" /usr/local/portage

However, the same symptoms occurred with versions 1.0.24-r5, 1.0.25_pre20150628 and 1.0.25_pre20150725 of the sane-backends package, so I believe the problem was not version-specific.

A note about scanning in Linux
An early developer’s Web site for the SANE pixma backend has the following warning:

If you grant a group a full permission to access the scanner (by using udev, hotplug, resmgr etc.), every members in the group will have full access rights not only for the scanner part but also for the other parts of the device i.e. printer, memory-card reader and fax. These users can bypass your system’s security policy and do everything with the device intentionally and unintentionally.

It is all very well to say that, but it is the only way I could get the backend to work reliably (almost). And, judging by the number of people who posted on the Web that they had to do the same with other Linux distributions, other manufacturers and models of MFPs, this is a common requirement in order to get Linux to work with MFP scanners. It’s not impressive when people have to resort to this to get something to work.

Note that the success of the approach described in this post is dependent on the contents and order of all the UDEV rules files. Just because the rules files I have posted above work in my case does not guarantee they will work in your case too. It depends what rules files your installation already has, what are their precise contents and in what order they are. In my opinion this is not a good concept.

I stand by my comments in the Conclusion of my first post regarding this problem. To have to jump through so many hoops to be able to scan using Linux on a computer connected to a MFP via USB is ridiculous in my opinion. The fact that it works reliably via a network connection does not alter that. I have been ‘scratching an itch’ as I enjoy tinkering, but I feel sorry for users who just need something that works without having to mess around for hours or days.

Background

  1. The problem of scanning using USB multi-function printers in Linux
  2. The problem of scanning using USB multi-function printers in Linux (continued)

The problem of scanning using USB multi-function printers in Linux (continued)

My previous post discussed the inability of the Linux installation on my main laptop to use the scanner of my Canon PIXMA MP560 MFP (multi-function peripheral) when they are connected via USB. Linux sees the MP560 as a single USB device with multiple interfaces: Interface 0 (scanner), Interface 1 (printer) and Interface 2 (USB mass storage). The basic problem seems to be that the usb-storage driver — whether built into the kernel or as an external module — claims the USB device and blocks access by userspace’s libusb, which is what the SANE backend (‘pixma‘, in the case of the MP560) uses to access the USB device. However, scanning works fine when using a network connection instead of the USB connection.

Attempts such as unbinding the usb-storage driver from the USB device — either manually or using a UDEV rule — in order to try and allow libusb/SANE to access the scanner, did not solve the problem. Although I can scan by connecting to the MP560 via my home network, the inability of the OS to scan via the USB interface piqued my interest, so I continued my investigations and below I discuss my latest findings.

Disabling kernel auto-binding

I learned from the interesting blog post Controlling USB device access on Linux how to stop the kernel automatically binding a driver to a USB device in the first place, as distinct from unbinding a driver after the kernel has bound it to a device. I thought this approach could be used to stop the usb-storage driver from binding to the MP560 and thus allow libusb/SANE to access Interface 0. The method using sysfs to stop the kernel binding the driver is to disable kernel USB auto-probing before launching a scanner application, by using the following command:

# echo 0 > /sys/bus/usb/drivers_autoprobe

This did indeed stop the kernel from automatically binding USB drivers to USB devices, but unfortunately libusb/SANE would still not access the MP560 scanner via USB. When drivers_autoprobe contains zero, applications such as XSane can use the network-connected MP560 as before, but still hang if the USB-connected MP560 is selected.

Unloading the usb-storage module

According to various blog and forum posts, some people have been able to use MFP scanners via USB after manually unloading the usb-storage module. I decided to try this. As I had built the kernel with the usb-storage driver internally rather than an external module, I first had to rebuild the kernel with CONFIG_USB_STORAGE=m instead of CONFIG_USB_STORAGE=y. Then I unloaded manually the usb_storage module using the command ‘rmmod usb_storage‘ and launched a scanner application, but the application still hung.

Disabling the usb-storage driver using a ‘quirk’

Then I had a thought: Perhaps there is a kernel ‘quirk’ to disable the usb-storage driver from binding to a specific USB device. Indeed there is (see Kernel Parameters or /usr/src/linux-<version>/Documentation/kernel-parameters.txt).

If the usb-storage driver is built into the kernel (CONFIG_USB_STORAGE=y), I would need to add the following kernel boot parameter to the kernel boot line:

usb-storage.quirks=04a9:173e:i

’04a9′ is the Vendor ID and ‘173e’ is the Product ID of the MP560. The ‘i‘ stands for ‘ignore’.

If the usb-storage driver is built as a kernel module (CONFIG_USB_STORAGE=m), I would need to create a file with a name such as /etc/modprobe.d/usb-storage.conf containing the following line:

options usb-storage quirks=04a9:173e:i

So I set up the quirk. Upon rebooting my laptop, the dmesg command reported the following:

usb 1-1.2.2: new high-speed USB device number 8 using ehci-pci
usb 1-1.2.2: New USB device found, idVendor=04a9, idProduct=173e
usb 1-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.2.2: Product: MP560 series
usb 1-1.2.2: Manufacturer: Canon
usb 1-1.2.2: SerialNumber: 1653C4
usb-storage 1-1.2.2:1.2: USB Mass Storage device detected
usb-storage 1-1.2.2:1.2: device ignored

Notice the final line. The quirk does indeed cause the usb-storage driver to ignore the MP560.

The lsusb command still shows the device, which is a good sign:

# lsusb
Bus 002 Device 005: ID 0bc2:3300 Seagate RSS LLC
Bus 002 Device 004: ID 0411:01d9 BUFFALO INC. (formerly MelCo., Inc.)
Bus 002 Device 003: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub
Bus 002 Device 002: ID 8087:8000 Intel Corp.
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 006: ID 5986:055c Acer, Inc
Bus 001 Device 004: ID 8087:07dc Intel Corp.
Bus 001 Device 007: ID 0603:00f2 Novatek Microelectronics Corp. Keyboard (Labtec Ultra Flat Keyboard)
Bus 001 Device 008: ID 04a9:173e Canon, Inc. MP560
Bus 001 Device 005: ID 045e:00d1 Microsoft Corp. Optical Mouse with Tilt Wheel
Bus 001 Device 003: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub
Bus 001 Device 002: ID 8087:8008 Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

# lsusb -t
/:  Bus 02.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/8p, 480M
        |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 4, If 0, Class=Mass Storage, Driver=usb-storage, 480M
            |__ Port 3: Dev 5, If 0, Class=Mass Storage, Driver=usb-storage, 480M
/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ehci-pci/2p, 480M
    |__ Port 1: Dev 2, If 0, Class=Hub, Driver=hub/6p, 480M
        |__ Port 2: Dev 3, If 0, Class=Hub, Driver=hub/4p, 480M
            |__ Port 1: Dev 5, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 2: Dev 8, If 0, Class=Vendor Specific Class, Driver=usbfs, 480M
            |__ Port 2: Dev 8, If 1, Class=Printer, Driver=, 480M
            |__ Port 2: Dev 8, If 2, Class=Mass Storage, Driver=, 480M
            |__ Port 4: Dev 7, If 0, Class=Human Interface Device, Driver=usbhid, 1.5M
            |__ Port 4: Dev 7, If 1, Class=Human Interface Device, Driver=usbhid, 1.5M
        |__ Port 3: Dev 4, If 0, Class=Wireless, Driver=btusb, 12M
        |__ Port 3: Dev 4, If 1, Class=Wireless, Driver=btusb, 12M
        |__ Port 4: Dev 6, If 0, Class=Video, Driver=uvcvideo, 480M
        |__ Port 4: Dev 6, If 1, Class=Video, Driver=uvcvideo, 480M

The output of the lsusb -v -d 04a9:173e command applicable to the MP560 is as follows:

Bus 001 Device 008: ID 04a9:173e Canon, Inc. MP560
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               2.00
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  idVendor           0x04a9 Canon, Inc.
  idProduct          0x173e MP560
  bcdDevice            0.04
  iManufacturer           1 Canon
  iProduct                2 MP560 series
  iSerial                 3 1653C4
  bNumConfigurations      1
  Configuration Descriptor:
    bLength                 9
    bDescriptorType         2
    wTotalLength           85
    bNumInterfaces          3
    bConfigurationValue     1
    iConfiguration          0 
    bmAttributes         0xc0
      Self Powered
    MaxPower                2mA
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        0
      bAlternateSetting       0
      bNumEndpoints           3
      bInterfaceClass       255 Vendor Specific Class
      bInterfaceSubClass      0 
      bInterfaceProtocol    255 
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x07  EP 7 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x88  EP 8 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x89  EP 9 IN
        bmAttributes            3
          Transfer Type            Interrupt
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0040  1x 64 bytes
        bInterval              11
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        1
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         7 Printer
      bInterfaceSubClass      1 Printer
      bInterfaceProtocol      2 Bidirectional
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x01  EP 1 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x82  EP 2 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
    Interface Descriptor:
      bLength                 9
      bDescriptorType         4
      bInterfaceNumber        2
      bAlternateSetting       0
      bNumEndpoints           2
      bInterfaceClass         8 Mass Storage
      bInterfaceSubClass      6 SCSI
      bInterfaceProtocol     80 Bulk-Only
      iInterface              0 
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x84  EP 4 IN
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
      Endpoint Descriptor:
        bLength                 7
        bDescriptorType         5
        bEndpointAddress     0x05  EP 5 OUT
        bmAttributes            2
          Transfer Type            Bulk
          Synch Type               None
          Usage Type               Data
        wMaxPacketSize     0x0200  1x 512 bytes
        bInterval               0
Device Qualifier (for other device speed):
  bLength                10
  bDescriptorType         6
  bcdUSB               2.00
  bDeviceClass            0 
  bDeviceSubClass         0 
  bDeviceProtocol         0 
  bMaxPacketSize0        64
  bNumConfigurations      1
can't get debug descriptor: Resource temporarily unavailable
Device Status:     0x0001
  Self Powered

The USB device created at boot was as follows:

# ls -la /dev/bus/usb/001/008
crw-rw-r--+ 1 root lp 189, 7 Jul 24 11:01 /dev/bus/usb/001/008

Whether run by the root user or under my user account, the SANE tools detected the MP560 scanner network and USB connections:

$ scanimage -L
device `pixma:MP560_192.168.1.78' is a CANON Canon PIXMA MP560 multi-function peripheral
device `pixma:04A9173E' is a CANON Canon PIXMA MP560 multi-function peripheral

$ sane-find-scanner

  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.

  # No SCSI scanners found. If you expected something different, make sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x04a9 [Canon], product=0x173e [MP560 series]) at libusb:001:008
  # Your USB scanner was (probably) detected. It may or may not be supported by
  # SANE. Try scanimage -L and read the backend's manpage.

  # Not checking for parallel port scanners.

  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

But scanner applications still hung! This time the message displayed by the dmesg command was:

usb 1-1.2.2: usbfs: interface 0 claimed by usbfs while 'scanimage' sets config #1

I unplugged the USB cable and plugged it in again. The output of the dmesg command was:

usb 1-1.2.2: USB disconnect, device number 8
usb 1-1.2.2: new high-speed USB device number 9 using ehci-pci
usb 1-1.2.2: New USB device found, idVendor=04a9, idProduct=173e
usb 1-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.2.2: Product: MP560 series
usb 1-1.2.2: Manufacturer: Canon
usb 1-1.2.2: SerialNumber: 1653C4
usb-storage 1-1.2.2:1.2: USB Mass Storage device detected
usb-storage 1-1.2.2:1.2: device ignored

I then launched XSane several times and each time I was able to select either the MP560 via my home network (pixma:MP560_192.168.1.78) or via the USB cable (pixma:04A9173E_1653C4) and scan successfully.

By the way, it is possible to scan via the command line instead of using a GUI scanner application. For example, tjhe following command will scan an A4 page via the MP560’s USB connection (see man scanimage for details of the options):

$ scanimage -d pixma:04A9173E_1653C4 -l 0 -t 0 -x 215 -y 297 --resolution 150 --mode Color | convert - scanned-page.png

So the problem is solved, right? Wrong! For whatever reason, scanning via the USB interface is not guaranteed to work every time I boot the laptop. Sometimes scanner applications (and the scanimage command) hang if I select the USB interface; at other times they don’t hang and scanning works fine. If scanning using the USB device is not working, if I unplug and re-insert the USB cable a few times it becomes possible to scan using the USB interface. And once scanning via the USB interface does work, from then onwards it works consistently during that session.

I had been using Version 1.0.24-r5 of the sane-backends package in Gentoo Linux, which is the latest stable version according to the Gentoo package manager. To check if that particular version of the SANE pixma backend might be the cause of the problem I installed the latest version available in the Gentoo package manager (currently 1.0.5_pre20150625). However it made no discernable difference.

To sum up, in my case the most successful approach so far has been to use a kernel ‘quirk’ to force the usb-storage driver to ignore the device and not bind to it. However, this approach does not result in libusb/SANE being able to access the scanner during every boot session, but, if access is successful, it remains successful during the current session. Even if access via the USB interface does not work initially, sometimes I can get it to work by unplugging and re-inserting the USB cable.

UPDATE (July 30, 2015): I have now managed to get scanning to work with almost 100% reliability when connected to the MP560 via USB — see my latest post for details.

The problem of scanning using USB multi-function printers in Linux

Whilst searching the Web I have found many other people experiencing this problem, which I believe happens as a consequence of the way Linux is designed. Basically, if you have a multi-function peripheral that you connect to your computer via USB, the chances are that either scanning or printing will not work. The Web is littered with blog posts, forum threads, mailing list posts and bug reports regarding this phenomenon. There are numerous suggested fixes, usually entailing the addition or modification of udev rules. Sometimes the suggested fixes work; often they don’t. Linux can be a major hassle where peripherals are concerned.

I have a Canon Pixma MP560 MFP (multi-function printer/peripheral), which is a printer, scanner and copier. It also has memory card slots and a USB pen drive socket, to be able to store images directly from the scanner without the need to connect a computer. The MP560 provides two alternative means of connection to a computer: USB and Wi-Fi. I normally connect it via USB to my Clevo W230SS laptop running Gentoo Linux (amd64), but I can also connect it to the laptop via my home Wi-Fi network. Either connection method allows me to print, but I can scan only via the wireless connection.

The dmesg command displays the following messages after I plug a USB cable from the MP560 into my laptop:

usb 1-1.2.2: new high-speed USB device number 8 using ehci-pci
usb 1-1.2.2: New USB device found, idVendor=04a9, idProduct=173e
usb 1-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1.2.2: Product: MP560 series
usb 1-1.2.2: Manufacturer: Canon
usb 1-1.2.2: SerialNumber: 1653C4
usb-storage 1-1.2.2:1.2: USB Mass Storage device detected
scsi host6: usb-storage 1-1.2.2:1.2
scsi 6:0:0:0: Direct-Access     Canon    MP560 series     0104 PQ: 0 ANSI: 2
sd 6:0:0:0: Attached scsi generic sg1 type 0
sd 6:0:0:0: [sdb] Attached SCSI removable disk

Notice that the device also has some internal storage.

The lsusb command shows the device:

$ lsusb
Bus 002 Device 002: ID 8087:8000 Intel Corp.
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 006: ID 5986:055c Acer, Inc
Bus 001 Device 004: ID 8087:07dc Intel Corp.
Bus 001 Device 007: ID 0603:00f2 Novatek Microelectronics Corp. Keyboard (Labtec Ultra Flat Keyboard)
Bus 001 Device 009: ID 04a9:173e Canon, Inc. MP560
Bus 001 Device 005: ID 045e:00d1 Microsoft Corp. Optical Mouse with Tilt Wheel
Bus 001 Device 003: ID 05e3:0606 Genesys Logic, Inc. USB 2.0 Hub / D-Link DUB-H4 USB 2.0 Hub
Bus 001 Device 002: ID 8087:8008 Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

My Linux user account is in the lp and scanner groups:

$ groups
disk lp wheel floppy uucp cron audio cdrom video games cdrw usb users plugdev crontab wireshark vboxusers scanner fitzcarraldo

The device is in the lp group and I can print without any trouble:

$ ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 root lp 189, 8 Jun 19 02:55 /dev/bus/usb/001/009

The usblp driver, a common cause of problems with USB printers, does not exist because I purposely did not set CONFIG_USB_PRINTER when I built the kernel, specifically to avoid such problems:

$ grep CONFIG_USB_PRINTER /usr/src/linux/.config
# CONFIG_USB_PRINTER is not set

so, obviously, the usblp driver is neither built into the kernel nor compiled as a module:

$ lsmod | grep usb
btusb                  22292  0
bluetooth             281605  27 bnep,hidp,btusb,rfcomm

I have the latest stable versions of the udev-related packages installed (as you can see below, I use eudev instead of udev):

$ eix -I udev
[I] dev-python/pyudev
     Available versions:  0.16.1-r1 {pygobject pyqt4 pyside test PYTHON_TARGETS="python2_7 python3_3 python3_4"}
     Installed versions:  0.16.1-r1(03:32:17 18/04/15)(pyqt4 -pygobject -pyside -test PYTHON_TARGETS="python2_7 python3_3 -python3_4")
     Homepage:            http://pyudev.readthedocs.org https://github.com/pyudev/pyudev
     Description:         Python binding to libudev

[I] sys-fs/eudev
     Available versions:  *1.3 *1.5.3-r1 1.9-r2 1.10-r2 ~2.1.1 ~3.0 3.1.2 ~3.1.2-r10 **9999 {doc gudev (+)hwdb introspection (+)keymap (+)kmod +modutils +openrc +rule-generator selinux static-libs test ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32"}
     Installed versions:  3.1.2(19:44:12 16/07/15)(gudev hwdb introspection kmod -doc -selinux -static-libs -test ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="32 64 -x32")
     Homepage:            https://github.com/gentoo/eudev
     Description:         Linux dynamic and persistent device naming support (aka userspace devfs)

[I] sys-fs/udev-init-scripts
     Available versions:  27^t [M]~29^t ~30^t **9999^t
     Installed versions:  27^t(05:29:06 09/04/15)
     Homepage:            http://www.gentoo.org
     Description:         udev startup scripts for openrc

[I] virtual/libgudev
     Available versions:  215-r1(0/0) 215-r2(0/0) 215-r3(0/0) ~230(0/0) {introspection static-libs systemd ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32"}
     Installed versions:  215-r3(10:18:16 11/06/15)(introspection -static-libs -systemd ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="64 -32 -x32")
     Description:         Virtual for libgudev providers

[I] virtual/libudev
     Available versions:  215-r1(0/1) {static-libs systemd ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32"}
     Installed versions:  215-r1(17:51:42 18/04/15)(-static-libs -systemd ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="32 64 -x32")
     Description:         Virtual for libudev providers

[I] virtual/udev
     Available versions:  215 ~217 {systemd}
     Installed versions:  215(05:28:55 09/04/15)(-systemd)
     Description:         Virtual to select between different udev daemon providers

Found 6 matches.

I have the latest stable SANE-related packages installed:

$ eix -I sane
[I] dev-perl/Sane
     Available versions:  (~)0.50.0-r1 {test}
     Installed versions:  0.50.0-r1(17:39:10 23/06/15)(-test)
     Homepage:            http://search.cpan.org/dist/Sane/
     Description:         The Sane module allows you to access SANE-compatible scanners in a Perl

[I] kde-apps/ksaneplugin
     Available versions:  (4) 4.14.3(4/4.14)
       {aqua debug}
     Installed versions:  4.14.3(4)(14:13:01 17/04/15)(-aqua -debug)
     Homepage:            http://www.kde.org/
     Description:         SANE Plugin for KDE

[I] kde-apps/libksane
     Available versions:  (4) 4.14.3(4/4.14)
       {aqua debug}
     Installed versions:  4.14.3(4)(13:55:44 17/04/15)(-aqua -debug)
     Homepage:            http://www.kde.org/
     Description:         SANE Library interface for KDE

[I] media-gfx/sane-backends
     Available versions:  1.0.24-r5 ~1.0.25_pre20150628 {avahi doc gphoto2 ipv6 snmp systemd threads usb v4l xinetd ABI_MIPS="n32 n64 o32" ABI_PPC="32 64" ABI_S390="32 64" ABI_X86="32 64 x32" SANE_BACKENDS="+abaton +agfafocus +apple +artec +artec_eplus48u +as6e +avision +bh +canon +canon630u +canon_dr -canon_pp +cardscan +coolscan +coolscan2 +coolscan3 +dc210 +dc240 +dc25 +dell1600n_net +dmc +epjitsu +epson +epson2 +fujitsu +genesys +gt68xx +hp +hp3500 +hp3900 +hp4200 +hp5400 +hp5590 +hpljm1005 -hpsj5s +hs2p +ibm +kodak +kodakaio +kvs1025 +kvs20xx kvs40xx +leo +lexmark +ma1509 +magicolor +matsushita +microtek +microtek2 +mustek -mustek_pp +mustek_usb mustek_usb2 +nec +net +niash +p5 +pie +pixma +plustek +plustek_pp -pnm +qcam +ricoh +rts8891 +s9036 +sceptre +sharp +sm3600 +sm3840 +snapscan +sp15c +st400 +stv680 +tamarack +teco1 +teco2 +teco3 +test +u12 +umax +umax1220u +umax_pp +xerox_mfp"}
     Installed versions:  1.0.24-r5(17:55:11 18/04/15)(avahi gphoto2 ipv6 usb v4l -doc -snmp -systemd -threads -xinetd ABI_MIPS="-n32 -n64 -o32" ABI_PPC="-32 -64" ABI_S390="-32 -64" ABI_X86="32 64 -x32" SANE_BACKENDS="abaton agfafocus apple artec artec_eplus48u as6e avision bh canon canon630u canon_dr cardscan coolscan coolscan2 coolscan3 dc210 dc240 dc25 dell1600n_net dmc epjitsu epson epson2 fujitsu genesys gt68xx hp hp3500 hp3900 hp4200 hp5400 hp5590 hpljm1005 hs2p ibm kodak kodakaio kvs1025 kvs20xx leo lexmark ma1509 magicolor matsushita microtek microtek2 mustek mustek_usb nec net niash p5 pie pixma plustek plustek_pp qcam ricoh rts8891 s9036 sceptre sharp sm3600 sm3840 snapscan sp15c st400 stv680 tamarack teco1 teco2 teco3 test u12 umax umax1220u umax_pp xerox_mfp -canon_pp -hpsj5s -kvs40xx -mustek_pp -mustek_usb2 -pnm")
     Homepage:            http://www.sane-project.org/
     Description:         Scanner Access Now Easy - Backends

[I] media-gfx/sane-frontends
     Available versions:  1.0.14 {gimp}
     Installed versions:  1.0.14(19:47:50 18/06/15)(gimp)
     Homepage:            http://www.sane-project.org
     Description:         Scanner Access Now Easy

[I] media-gfx/xsane
     Available versions:  0.999-r1 {gimp jpeg lcms nls ocr png tiff}
     Installed versions:  0.999-r1(12:03:12 19/04/15)(gimp jpeg lcms nls png tiff -ocr)
     Homepage:            http://www.xsane.org/
     Description:         graphical scanning frontend

Found 6 matches.

The following SANE backends were installed when I installed SANE:

$ ls -F1 /etc/sane.d/ | columns -c 3 -w 20
abaton.conf         agfafocus.conf      apple.conf
artec.conf          artec_eplus48u.conf avision.conf
bh.conf             canon.conf          canon630u.conf
canon_dr.conf       cardscan.conf       coolscan.conf
coolscan2.conf      coolscan3.conf      dc210.conf
dc240.conf          dc25.conf           dell1600n_net.conf
dll.conf            dll.d/              dmc.conf
epjitsu.conf        epson.conf          epson2.conf
fujitsu.conf        genesys.conf        gphoto2.conf
gt68xx.conf         hp.conf             hp3900.conf
hp4200.conf         hp5400.conf         hs2p.conf
ibm.conf            kodak.conf          kodakaio.conf
leo.conf            lexmark.conf        ma1509.conf
magicolor.conf      matsushita.conf     microtek.conf
microtek2.conf      mustek.conf         mustek_usb.conf
nec.conf            net.conf            p5.conf
pie.conf            pixma.conf          plustek.conf
plustek_pp.conf     qcam.conf           ricoh.conf
rts8891.conf        s9036.conf          saned.conf
sceptre.conf        sharp.conf          sm3840.conf
smfp.conf           snapscan.conf       sp15c.conf
st400.conf          stv680.conf         tamarack.conf
teco1.conf          teco2.conf          teco3.conf
test.conf           u12.conf            umax.conf
umax1220u.conf      umax_pp.conf        v4l.conf
xerox_mfp.conf

I checked all the SANE backend configuration files, and none of them mention the MP560 (I was not expecting them to mention it, as, according to man sane-pixma, the pixma backend detects Canon PIXMA USB devices automatically):

$ grep -rnwi /etc/sane.d/ -e "173e"
$

The SANE file dll.conf does list the pixma backend configuration file which is only for declaring networked Canon PIXMA devices, as the pixma backend detects Canon USB devices automatically):

$ grep pixma /etc/sane.d/dll.conf
pixma

$ cat /etc/sane.d/pixma.conf
# pixma.conf configuration for the sane pixma backend
#
# define URI's of scanners (one per line)
# This is only used for network scanners.
# normally scanners will be detected by sending a broadcast
# if this does not work under your OS, or if the scanners
# are on a different subnet, configure your scanners URI here
#
# method must be bjnp
# port number can normally be left out, port 8612 is used as default
# Example:
# bjnp://myscanner.my.domain:8612
# bjnp://printer-1.pheasant.org
#

I don’t think it is even used these days, but the file /etc/hotplug/usb/libsane.usermap already includes the device:

# Canon PIXMA MP560
libusbscanner 0x0003 0x04a9 0x173e 0x0000 0x0000 0x00 0x00 0x00 0x00 0x00 0x00 0x00000000

The file /lib64/udev/rules.d/41-libsane.rules already includes the device:

# Canon PIXMA MP560
ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

However, scanning from Linux via USB is a troubled affair. Very occasionally the scanner application (XSane, Simple Scan, gscan2pdf, or whatever) will launch and the scanner works, but usually the scanner application just hangs and the dmesg command shows one or more error messages such as the following:

usb 1-1.2.2: usbfs: interface 2 claimed by usb-storage while 'xsane' sets config #1

usb 1-1.2.2: usbfs: interface 2 claimed by usb-storage while 'gscan2pdf' sets config #1

I have USB mass storage support enabled in the kernel so that my laptop can access external USB mass storage devices:

$ grep CONFIG_USB_STORAGE= /usr/src/linux/.config
CONFIG_USB_STORAGE=y

As the three interfaces (printer, scanner and internal storage) are all accessed as a single USB device (/dev/bus/usb/001/009, or whatever), there appears to be a conflict between the kernel claiming the MFP’s internal mass storage and SANE trying to access the scanner. I do not want to disable the kernel’s USB mass storage support (not even by rebuilding the kernel with CONFIG_USB_STORAGE=m and temporarily unloading manually the usb-storage module, as some people suggest), as I would not be able to access my external USB mass storage devices.

The scanimage and sane-find-scanner utilities detect the scanner correctly via USB:

$ scanimage -L
device `v4l:/dev/video0' is a Noname BisonCam, NB Pro virtual device
device `pixma:04A9173E_1653C4' is a CANON Canon PIXMA MP560 multi-function peripheral

(The BisonCam is the Webcam built into my laptop.)

$ sane-find-scanner

  # sane-find-scanner will now attempt to detect your scanner. If the
  # result is different from what you expected, first make sure your
  # scanner is powered up and properly connected to your computer.

  # No SCSI scanners found. If you expected something different, make sure that
  # you have loaded a kernel SCSI driver for your SCSI adapter.

found USB scanner (vendor=0x04a9 [Canon], product=0x173e [MP560 series]) at libusb:001:009
  # Your USB scanner was (probably) detected. It may or may not be supported by
  # SANE. Try scanimage -L and read the backend's manpage.

  # Not checking for parallel port scanners.

  # Most Scanners connected to the parallel port or other proprietary ports
  # can't be detected by this program.

  # You may want to run this program as root to find all devices. Once you
  # found the scanner devices, be sure to adjust access permissions as
  # necessary.

The scanimage test commands do not indicate any problem:

$ scanimage -d test -T
scanimage: scanning image of size 157x196 pixels at 8 bits/pixel
scanimage: acquiring gray frame, 8 bits/sample
scanimage: reading one scanline, 157 bytes...   PASS
scanimage: reading one byte...          PASS
scanimage: stepped read, 2 bytes...     PASS
scanimage: stepped read, 4 bytes...     PASS
scanimage: stepped read, 8 bytes...     PASS
scanimage: stepped read, 16 bytes...    PASS
scanimage: stepped read, 32 bytes...    PASS
scanimage: stepped read, 64 bytes...    PASS
scanimage: stepped read, 128 bytes...   PASS
scanimage: stepped read, 256 bytes...   PASS
scanimage: stepped read, 255 bytes...   PASS
scanimage: stepped read, 127 bytes...   PASS
scanimage: stepped read, 63 bytes...    PASS
scanimage: stepped read, 31 bytes...    PASS
scanimage: stepped read, 15 bytes...    PASS
scanimage: stepped read, 7 bytes...     PASS
scanimage: stepped read, 3 bytes...     PASS

$ scanimage -d pixma -T
scanimage: scanning image of size 638x877 pixels at 24 bits/pixel
scanimage: acquiring RGB frame, 8 bits/sample
scanimage: reading one scanline, 1914 bytes...  PASS
scanimage: reading one byte...          PASS
scanimage: stepped read, 2 bytes...     PASS
scanimage: stepped read, 4 bytes...     PASS
scanimage: stepped read, 8 bytes...     PASS
scanimage: stepped read, 16 bytes...    PASS
scanimage: stepped read, 32 bytes...    PASS
scanimage: stepped read, 64 bytes...    PASS
scanimage: stepped read, 128 bytes...   PASS
scanimage: stepped read, 256 bytes...   PASS
scanimage: stepped read, 512 bytes...   PASS
scanimage: stepped read, 1024 bytes...  PASS
scanimage: stepped read, 2048 bytes...  PASS
scanimage: stepped read, 2047 bytes...  PASS
scanimage: stepped read, 1023 bytes...  PASS
scanimage: stepped read, 511 bytes...   PASS
scanimage: stepped read, 255 bytes...   PASS
scanimage: stepped read, 127 bytes...   PASS
scanimage: stepped read, 63 bytes...    PASS
scanimage: stepped read, 31 bytes...    PASS
scanimage: stepped read, 15 bytes...    PASS
scanimage: stepped read, 7 bytes...     PASS
scanimage: stepped read, 3 bytes...     PASS

As mentioned earlier, the udev/eudev rules file appears to contain a valid rule for the scanner:

# Canon PIXMA MP560
ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

Notice the rule assigns the device’s group to be ‘scanner‘, not ‘lp‘, although changing the group assignment to ‘lp‘ in the rule makes no discernable difference to the scanning problem in my case. As the device’s group is actually ‘lp‘, I assume another rule overrides this rule, but I have no idea which rule it is and in which rules file it occurs.

Occasionally I am lucky and scanning does work, but, more often than not, scanner applications cannot access the scanner and just hang.

A work-around if the peripheral also has a network interface

I configured my home network router always to use the IP address 192.168.1.78 for the MP560 and I added the following line to the file /etc/sane.d/pixma.conf in order to be able to scan via Wi-Fi instead of USB (I have the package cups-bjnp installed for printing purposes, but I am not sure if that package is also needed by SANE in this case):

bjnp://192.168.1.78

With the above line added to /etc/sane.d/pixma.conf the scanimage utility detects the scanner correctly via both the Wi-Fi connection and the USB interface:

$ scanimage -L
device `v4l:/dev/video0' is a Noname BisonCam, NB Pro virtual device
device `pixma:MP560_192.168.1.78' is a CANON Canon PIXMA MP560 multi-function peripheral
device `pixma:04A9173E_1653C4' is a CANON Canon PIXMA MP560 multi-function peripheral

So, as I usually cannot get scanning to work via USB, I can scan via Wi-Fi instead. It’s a work-around, not a solution, but at least by doing that I can scan reliably as well as print. Of course you can’t use such a work-around if you have a model of MFP that only provides a USB connection.

Failed experiments

Experiment 1

I also tried unbinding the usb-storage driver from the usb device:

# ls /sys/bus/usb/drivers
btusb hub usb usb-storage usbfs usbhid uvcvideo
# ls /sys/bus/usb/drivers/btusb/
1-1.3:1.0 1-1.3:1.1 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/hub
1-0:1.0 1-1.2:1.0 1-1:1.0 2-0:1.0 2-1:1.0 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/usb
1-1 1-1.2 1-1.2.1 1-1.2.2 1-1.2.4 1-1.3 1-1.4 2-1 bind uevent unbind usb1 usb2
# ls /sys/bus/usb/drivers/usb-storage/
1-1.2.2:1.2 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/usbfs
bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/usbhid
1-1.2.1:1.0 1-1.2.4:1.0 1-1.2.4:1.1 bind module new_id remove_id uevent unbind
# ls /sys/bus/usb/drivers/uvcvideo
1-1.4:1.0 1-1.4:1.1 bind module new_id remove_id uevent unbind
# tree /sys/bus/usb/drivers/usb-storage/
/sys/bus/usb/drivers/usb-storage/
β”œβ”€β”€ 1-1.2.2:1.2 -> ../../../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/1-1.2.2/1-1.2.2:1.2
β”œβ”€β”€ bind
β”œβ”€β”€ module -> ../../../../module/usb_storage
β”œβ”€β”€ new_id
β”œβ”€β”€ remove_id
β”œβ”€β”€ uevent
└── unbind

2 directories, 5 files
# echo -n "1-1.2.2:1.2" > /sys/bus/usb/drivers/usb-storage/unbind
# tree /sys/bus/usb/drivers/usb-storage/
/sys/bus/usb/drivers/usb-storage/
β”œβ”€β”€ bind
β”œβ”€β”€ module -> ../../../../module/usb_storage
β”œβ”€β”€ new_id
β”œβ”€β”€ remove_id
β”œβ”€β”€ uevent
└── unbind

1 directory, 5 files
# tree /sys/bus/usb/devices/1-1.2.2:1.2
/sys/bus/usb/devices/1-1.2.2:1.2
β”œβ”€β”€ bAlternateSetting
β”œβ”€β”€ bInterfaceClass
β”œβ”€β”€ bInterfaceNumber
β”œβ”€β”€ bInterfaceProtocol
β”œβ”€β”€ bInterfaceSubClass
β”œβ”€β”€ bNumEndpoints
β”œβ”€β”€ ep_05
β”‚Β Β  β”œβ”€β”€ bEndpointAddress
β”‚Β Β  β”œβ”€β”€ bInterval
β”‚Β Β  β”œβ”€β”€ bLength
β”‚Β Β  β”œβ”€β”€ bmAttributes
β”‚Β Β  β”œβ”€β”€ direction
β”‚Β Β  β”œβ”€β”€ interval
β”‚Β Β  β”œβ”€β”€ power
β”‚Β Β  β”œβ”€β”€ type
β”‚Β Β  β”œβ”€β”€ uevent
β”‚Β Β  └── wMaxPacketSize
β”œβ”€β”€ ep_84
β”‚Β Β  β”œβ”€β”€ bEndpointAddress
β”‚Β Β  β”œβ”€β”€ bInterval
β”‚Β Β  β”œβ”€β”€ bLength
β”‚Β Β  β”œβ”€β”€ bmAttributes
β”‚Β Β  β”œβ”€β”€ direction
β”‚Β Β  β”œβ”€β”€ interval
β”‚Β Β  β”œβ”€β”€ power
β”‚Β Β  β”œβ”€β”€ type
β”‚Β Β  β”œβ”€β”€ uevent
β”‚Β Β  └── wMaxPacketSize
β”œβ”€β”€ modalias
β”œβ”€β”€ power
β”œβ”€β”€ subsystem -> ../../../../../../../../bus/usb
β”œβ”€β”€ supports_autosuspend
└── uevent

6 directories, 27 files

After unbinding the usb-storage driver from the USB device, no more messages such as ‘usbfs: interface 2 claimed by usb-storage while 'xsane' sets config #1‘ are added to /var/log/messages when I launch a scanner application and select the USB device, but the scanner application still hangs (e.g. the XSane windows do not appear until I switch off the MP560 or unplug the USB cable). This happens irrespective of whether the USB device permissions are:

# ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 root lp 189, 8 Jul 20 20:35 /dev/bus/usb/001/009

or:

# ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 fitzcarraldo lp 189, 8 Jul 20 20:35 /dev/bus/usb/001/009

or:

# ls -la /dev/bus/usb/001/009
crw-rw-r--+ 1 fitzcarraldo scanner 189, 8 Jul 20 20:51 /dev/bus/usb/001/009

To reiterate, neither unbinding the usb-storage driver from the USB device first nor changing the owner and group of the USB device solves the problem. So possibly the problem is not caused by udev or by a USB driver, but by the SANE software.

Experiment 2

I found a thread in the SANE developers’ mailing list about the same problem with a different model of MFP: Help needed diagnosing strange failure to scan with Samsung SCX-4500W. The same user posted the same query in the Arch Linux forums: [SOLVED] Samsung SCX4500W MFP can’t get scanner to work. Like my Canon PIXMA MP560, that MFP has more than one interface in a single USB device. Notice in the Arch Linux thread that the user never found a solution and finally adopted the same work-around I use, namely to scan via a network interface rather than via the USB interface.

Theodore Kilgore gives a good explanation in that SANE developers’ mailing list thread of why the problem occurs in Linux, and Thorsten MΓΌller’s post suggests a udev rule that sets the permissions for the MFP so that SANE, CUPS and logged-in users can all access the USB device. All I had to do was replace references to Samsung (such as the vendor ID and product ID) with those for my Canon PIXMA MP560. I left everything else in my installation exactly the way it was (for example I did not touch /lib64/udev/rules.d/41-libsane.rules and /lib64/udev/rules.d/70-printers.rules). The only thing I did was to add a udev rules file /etc/udev/rules.d/99-canon-mp560.rules with the following contents:

# ACL settings for Canon PIXMA MP560 printer MFP
ATTR{idVendor}=="04a9", ATTR{idProduct}=="173e", GOTO="canon"
GOTO="canon_end"

LABEL="canon"
RUN+="/bin/setfacl -m g:scanner:rw -m g:lp:rw $env{DEVNAME}"
TEST=="/var/run/ConsoleKit/database", \
        RUN+="udev-acl --action=$env{ACTION} --device=$env{DEVNAME}"

LABEL="canon_end"

Both /bin/setfacl and /var/run/ConsoleKit/database exist in my installation, and, as shown earlier, my user account is a member of both the lp and scanner groups. After adding the above file, I rebooted and it appears the rule works as intended:

# getfacl /dev/bus/usb/001/009
getfacl: Removing leading '/' from absolute path names
# file: dev/bus/usb/001/009
# owner: root
# group: lp
user::rw-
user:fitzcarraldo:rw-
group::rw-
group:lp:rw-
group:scanner:rw-
mask::rw-
other::r--

However, although I was still able to print I still could not scan. Mind you, the line beginning ‘TEST==‘ in the file /etc/udev/rules.d/99-canon-mp560.rules is also in the file /lib64/udev/rules.d/70-udev-acl.rules, but I’m no expert in udev rules, which are frankly beyond the ability of most users.

Experiment 3

I found a blog post about the same problem but with a Canon MP210 MFP: Canon multifunction printer: getting the printer drivers and scanner to work in debian/ubuntu/mint. This post suggested creating a udev rule file /etc/udev/rules.d/40-scanner-permissions.rules containing the following:

# usb scanner
SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", MODE:="0666"
SUBSYSTEM=="usb_device",MODE:="0666"

but, although the rule appears to work as intended, it is still not possible to scan in my case. I then changed the file name to /etc/udev/rules.d/95-scanner-permissions.rules, but that made no difference in my case.

Experiment 4

I also tried changing MODE="0664" to MODE="0666" in the following line in the file /lib64/udev/rules.d/50-udev-default.rules but that made no difference either:

SUBSYSTEM=="usb", ENV{DEVTYPE}=="usb_device", MODE="0664"

Experiment 5

I am able to change the group of the USB device to ‘scanner‘ instead of ‘lp‘ by adding a rules file /lib64/udev/rules.d/99-canon.rules (apparently 41-libsane.rules does not work as intended because it is overruled by a higher-numbered file, but I have no idea which one, as 41-libsane.rules is the only one explicitly mentioning the MP560) containing the following:

ATTRS{idVendor}=="04a9", ATTRS{idProduct}=="173e", MODE="0664", GROUP="scanner", ENV{libsane_matched}="yes"

But scanning still does not work, whether or not I unbind the usb-storage driver from the USB device first and whether or not I change the owner and group of the USB device to root:lp, root:scanner, fitzcarraldo:lp or fitzcarraldo:scanner.

Conclusion

Although my installation can print via USB, scanning via USB does not work, whether or not the usb-storage driver is bound to the USB device and whoever is the owner and group of the USB device. So it could be that the problem is not caused by udev or by the kernel (a USB driver), but by the SANE software itself. However, I think it is more likely to be some sort of contention between kernel and userspace, despite unbinding the usb-storage driver from the device. Although I’m not excluding the possibility of a bug in SANE, irrespective of that it seems to me that the way GNU/Linux handles multiple interfaces of a single USB device is flawed. The udev design results in a morass of confusing and potentially conflicting rules in umpteen files in different directories, and the apparently uncoordinated independent demands on the same USB interface by the kernel and userspace are another potential source of problems. There is no standardisation in the udev rules files and their contents between the different Linux distributions, making investigation and solution of such problems even more complicated. Having to resort to work-arounds such as scanning via a network interface or scanning to a USB pen drive or memory card is a poor way of circumventing the problem, and is of no help anyway if a multi-function peripheral does not have a network interface, pen drive socket or memory card slot.

UPDATE (July 24, 2015): I have tried some other approaches, and had more success using a ‘quirk’ for the usb-storage driver — see my next post for details.

Addendum: How to stop scanning applications detecting a Webcam

By the way, to stop XSane and other scanning applications detecting my Webcam via the Video for Linux SANE backend, I commented out all the device lines in the file /etc/sane.d/v4l.conf like so:

$ cat
# In order to use the v4linux backend you have to give the device
# You can enable multiple lines if
# you really have multible v4l devices.
#
#/dev/bttv0
#/dev/video0
#/dev/video1
#/dev/video2
#/dev/video3

Laptop Mode Tools revisited due to a change in its functionality

The site statistics for this blog can be quite revealing. For example, over the last two or three months I noticed that my post How to prevent a USB mouse auto-suspending in Linux when a laptop’s power supply is disconnected has consistently been one of the most viewed. Given the problems I experienced with Laptop Mode Tools 1.65 (see my Gentoo Linux Forums post Bug in laptop-mode-tools-1.65? and Gentoo Linux Bugzilla Bug Report No. 520124), I was not entirely surprised. Thanks to fellow Gentoo Linux and Laptop Mode Tools user Ted Tanberry I learned that Version 1.65 had stopped using Laptop Mode Tools module usb-autosuspend, and started using Laptop Mode Tools module runtime-pm instead. At least that was the developer’s intention, but he had not implemented it correctly. The aforementioned Gentoo Linux bug report explains in detail the problem with Version 1.65.

The situation in my Gentoo Linux installation with laptop-mode-tools-1.64 installed, providing the functionality I desired, was as follows:

a. The precise package installed:

# eix -I laptop-mode-tools
[U] app-laptop/laptop-mode-tools
Available versions: 1.64 (~)1.65 (~)1.65-r1 (~)1.66 {+acpi apm bluetooth scsi}
Installed versions: 1.64(10:04:43 21/10/14)(acpi bluetooth -apm -scsi)
Homepage: http://www.samwel.tk/laptop_mode/
Description: Linux kernel laptop_mode user-space utilities

b. The auto-suspend state when the laptop PSU was connected:

# for d in /sys/bus/usb/devices/[0-9]* ; do if [[ -e $d/product ]] ; then echo -e "`basename $d`\t`cat $d/power/control`\t`cat $d/speed`\t`cat $d/product`" ; fi ; done
1-1.2 on 1.5 USB Laser Mouse
2-1.2 on 12 Fingerprint Sensor
2-1.3 on 480 USB 2.0 Camera

c. The contents of the file /lib64/udev/rules.d/99-laptop-mode.rules:

ACTION=="change", SUBSYSTEM=="power_supply", RUN+="lmt-udev auto"
ACTION=="add|remove", SUBSYSTEM=="machinecheck", RUN+="lmt-udev auto"
ACTION=="add|remove", SUBSYSTEM=="usb", RUN+="lmt-udev force modules=usb-autosuspend devices=%k"

d. The contents of file /etc/laptop-mode/conf.d/usb-autosuspend.conf:

#
# Configuration file for Laptop Mode Tools module usb-autosuspend.
#
# For more information, consult the laptop-mode.conf(8) manual page.
#
 
 
###############################################################################
# USB autosuspend settings
# ------------------------
#
# If you enable this setting, laptop mode tools will automatically enable the
# USB autosuspend feature for all devices.
#
# NOTE: Some USB devices claim they support autosuspend, but implement it in a
# broken way. This can mean keyboards losing keypresses, or optical mice turning
# their LED completely off. If you have a device that misbehaves, add its USB ID
# to the blacklist below and complain to your hardware vendor.
################################################################################
 
# Enable debug mode for this module
# Set to 1 if you want to debug this module
DEBUG=0
 
# Enable USB autosuspend feature?
# Set to 0 to disable
CONTROL_USB_AUTOSUSPEND="auto"
 
# Set this to use opt-in/whitelist instead of opt-out/blacklist for deciding
# which USB devices should be autosuspended.
# AUTOSUSPEND_USE_WHITELIST=0 means AUTOSUSPEND_*_BLACKLIST will be used.
# AUTOSUSPEND_USE_WHITELIST=1 means AUTOSUSPEND_*_WHITELIST will be used.
AUTOSUSPEND_USE_WHITELIST=0
 
# The list of USB IDs that should not use autosuspend. Use lsusb to find out the
# IDs of your USB devices.
# Example: AUTOSUSPEND_USBID_BLACKLIST="046d:c025 0123:abcd"
AUTOSUSPEND_USBID_BLACKLIST="046d:c052"
 
# The list of USB driver types that should not use autosuspend.  The driver
# type is given by "DRIVER=..." in a USB device's uevent file.
# Example: AUTOSUSPEND_USBID_BLACKLIST="usbhid usb-storage"
AUTOSUSPEND_USBTYPE_BLACKLIST=""
 
# The list of USB IDs that should use autosuspend. Use lsusb to find out the
# IDs of your USB devices.
# Example: AUTOSUSPEND_USBID_WHITELIST="046d:c025 0123:abcd"
AUTOSUSPEND_USBID_WHITELIST=""
 
# The list of USB driver types that should use autosuspend.  The driver
# type is given by "DRIVER=..." in a USB device's uevent file.
# Example: AUTOSUSPEND_USBTYPE_WHITELIST="usbhid usb-storage"
AUTOSUSPEND_USBTYPE_WHITELIST=""
 
# Trigger auto-suspension of the USB deivce under conditional circumstances
BATT_SUSPEND_USB=1
LM_AC_SUSPEND_USB=0
NOLM_AC_SUSPEND_USB=0
 
# USB Auto-Suspend timeout in seconds
# Number of seconds after which the USB devices should suspend
AUTOSUSPEND_TIMEOUT=2

Having experienced the problems with the buggy Laptop Mode Tools 1.65, I re-installed 1.64 and had been using that successfully until a week ago. Then I noticed that 1.66 had been released, so I installed it:

# emerge laptop-mode-tools
.
.
.
>>> Installing (1 of 1) app-laptop/laptop-mode-tools-1.66::gentoo
* To enable automatic power state event handling,
* e.g. enabling laptop_mode after unplugging the battery,
* both laptop_mode and the acpid daemon must be
* added to default runlevel:
* # rc-update add laptop_mode default
>>> Auto-cleaning packages...

>>> No outdated packages were found on your system.

* GNU info directory index is up-to-date.

I would not have expected that ewarn message about adding laptop_mode to the default runlevel, as the ebuild is only supposed to display the warning if laptop_mode is not assigned to the default runlevel. But, sure enough, something had removed it:

# rc-update show -v | grep laptop
laptop_mode |
# rc-update show -v | grep acpi
acpid |      default

I don’t know what removed laptop_mode from the default runlevel. It was certainly assigned previously, as proved by Laptop Mode Tools 1.64 working as expected when I connected and disconnected the laptop’s PSU from the mains (see my earlier post). Anyway, I re-added it:

# rc-update add laptop_mode default
* service laptop_mode added to runlevel default

If you use systemd instead of OpenRC, instead of adding laptop_mode to the default runlevel you would need to use the following command:

# systemctl enable laptop_mode.service

Notice that the incorrect contents of 99-laptop-mode.rules and /etc/laptop-mode/laptop-mode.conf that were present in Laptop Mode Tools 1.65 have been fixed in 1.66:

# cat /lib64/udev/rules.d/99-laptop-mode.rules
ACTION=="change", SUBSYSTEM=="power_supply", RUN+="lmt-udev auto"
ACTION=="add|remove", SUBSYSTEM=="machinecheck", RUN+="lmt-udev auto force"
ACTION=="add|remove", SUBSYSTEM=="usb", RUN+="lmt-udev force modules=runtime-pm devices=%k"

# cat /etc/laptop-mode/laptop-mode.conf | grep usb-autosuspend
#

The ebuild for Laptop Mode Tools 1.66 did not delete the now-redundant file /etc/laptop-mode/conf.d/usb-autosuspend.conf but it is presumably ignored by 1.66 anyway.

From now on I must configure the contents of /etc/laptop-mode/conf.d/runtime-pm.conf instead. After installing Laptop Mode Tools 1.66 it contained the following:

#
# Configuration file for Laptop Mode Tools module runtime-pm
#
# For more information, consult the laptop-mode.conf(8) manual page.
#


###############################################################################
# Runtime Power Management Settings
# ---------------------------------
#
#__COMMENT If you enable this setting, laptop mode tools will automatically enable
#__COMMENT the Runtime Power Management feature for all devices.
#__COMMENT
#__COMMENT NOTE: Some devices claim they support autosuspend, but implement it in a
#__COMMENT broken way. This can mean keyboards losing keypresses, or optical mice
#__COMMENT turning their LED completely off. If you have a device that misbehaves,
#__COMMENT add its DEVICE ID to the blacklist section below and complain to your
#__COMMENT hardware / device driver contact
#
################################################################################

# Enable debug mode for this module
# Set to 1 if you want to debug this module
DEBUG=0

# Enable Runtime autosuspend feature?
# Set to 0 to disable
CONTROL_RUNTIME_AUTOSUSPEND=1

# Set this to use opt-in/whitelist instead of opt-out/blacklist for deciding
# which devices should be autosuspended.
# AUTOSUSPEND_USE_WHITELIST=0 means AUTOSUSPEND_*_BLACKLIST will be used.
# AUTOSUSPEND_USE_WHITELIST=1 means AUTOSUSPEND_*_WHITELIST will be used.
AUTOSUSPEND_USE_WHITELIST=0

# The list of Device IDs that should not use autosuspend. Use system commands or
# look into sysfs to find out the IDs of your devices.
# Example: AUTOSUSPEND_DEVID_BLACKLIST="046d:c025 0123:abcd"
AUTOSUSPEND_RUNTIME_DEVID_BLACKLIST=""

# The list of device driver types that should not use autosuspend.  The driver
# type is given by "DRIVER=..." in a device's uevent file.
# Example: AUTOSUSPEND_DEVID_BLACKLIST="usbhid usb-storage"
AUTOSUSPEND_RUNTIME_DEVTYPE_BLACKLIST=""

# The list of Device IDs that should use autosuspend. Use system commands or
# look into sysfs to find out the IDs of your devices.
# Example: AUTOSUSPEND_DEVID_WHITELIST="046d:c025 0123:abcd"
AUTOSUSPEND_RUNTIME_DEVID_WHITELIST=""

# The list of device driver types that should use autosuspend.  The driver
# type is given by "DRIVER=..." in a device's uevent file.
# Example: AUTOSUSPEND_DEVTYPE_WHITELIST="usbhid usb-storage"
AUTOSUSPEND_RUNTIME_DEVTYPE_WHITELIST=""

# Trigger auto-suspension of the deivce under conditional circumstances
# Warning: DO NOT CHANGE THESE DEFAUTLS UNLESS YOU KNOW
BATT_SUSPEND_RUNTIME=1
LM_AC_SUSPEND_RUNTIME=1
NOLM_AC_SUSPEND_RUNTIME=1

# Auto-Suspend timeout in seconds
# Number of seconds after which the USB devices should suspend
AUTOSUSPEND_TIMEOUT=2

So, in order to stop my laptop’s USB mouse, USB external keyboard and some internal USB devices from going to sleep when my laptop is only on battery power, I made the following change to a line in /etc/laptop-mode/conf.d/runtime-pm.conf:

# External keyboard at one office, internal Webcam, internal fingerprint sensor, Logitek NX50 notebook mouse
AUTOSUSPEND_RUNTIME_DEVID_BLACKLIST="03f0:0024 064e:a115 147e:1001 046d:c052"

My earlier post about Laptop Mode Tools explained one method for finding the device ID for each USB device, but the lsusb command can also be used:

# lsusb
Bus 002 Device 005: ID 03f0:0024 Hewlett-Packard KU-0316 Keyboard <---- External keyboard at one office
Bus 002 Device 004: ID 064e:a115 Suyin Corp. <---- Built-in Webcam
Bus 002 Device 003: ID 147e:1001 Upek TCS5B Fingerprint sensor <---- Built-in fingerprint sensor
Bus 002 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 046d:c052 Logitech, Inc. <----Logitech NX50 notebook mouse
Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Although the Laptop Mode Tools usb-autosuspend module is supposed to be unused in 1.66, I edited /etc/laptop-mode/conf.d/usb-autosuspend.conf (which was not deleted by the 1.66 ebuild) and changed CONTROL_USB_AUTOSUSPEND="auto" to CONTROL_USB_AUTOSUSPEND="0" just to be on the safe side.

How to prevent a USB mouse auto-suspending in Linux when a laptop’s power supply is disconnected

I found that my USB mouse (and external USB keyboard) went to sleep when the mains power supply was disconnected from my laptop. This was annoying because I had to click a mouse button and wait a couple of seconds in order to wake up the mouse. You can see from the console output below that several USB devices were being auto-suspended when I unplugged the laptop PSU:

# # PSU is currently connected.
# for d in /sys/bus/usb/devices/[0-9]* ; do if [[ -e $d/product ]] ; then echo -e "`basename $d`\t`cat $d/power/control`\t`cat $d/speed`\t`cat $d/product`" ; fi ; done
1-1.2 on 1.5 USB Laser Mouse
1-1.3 on 12 BCM2046 Bluetooth Device
2-1.2 on 12 Fingerprint Sensor
2-1.3 on 480 USB 2.0 Camera
2-1.6 on 1.5 USB Keyboard
# # Now I will disconnect the PSU...
# # PSU is currently disconnected.
# for d in /sys/bus/usb/devices/[0-9]* ; do if [[ -e $d/product ]] ; then echo -e "`basename $d`\t`cat $d/power/control`\t`cat $d/speed`\t`cat $d/product`" ; fi ; done
1-1.2 auto 1.5 USB Laser Mouse
1-1.3 auto 12 BCM2046 Bluetooth Device
2-1.2 auto 12 Fingerprint Sensor
2-1.3 auto 480 USB 2.0 Camera
2-1.6 auto 1.5 USB Keyboard
#

I found out the Vendor ID (046d) and Product ID (c052) of my Logitech NX50 USB portable/travel mouse by unplugging then reconnecting the USB mouse and using the dmesg command:

[13628.909728] usb 1-1.2: USB disconnect, device number 5
[13634.454132] usb 1-1.2: new low-speed USB device number 6 using ehci_hcd
[13634.535107] usb 1-1.2: New USB device found, idVendor=046d, idProduct=c052
[13634.535111] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[13634.535113] usb 1-1.2: Product: USB Laser Mouse
[13634.535115] usb 1-1.2: Manufacturer: Logitech
[13634.540168] input: Logitech USB Laser Mouse as /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/1-1.2:1.0/input/input17
[13634.540582] hid-generic 0003:046D:C052.0005: input,hidraw0: USB HID v1.10 Mouse [Logitech USB Laser Mouse] on usb-0000:00:1a.0-1.2/input0

First I tried creating a local Udev rule:

# cat /etc/udev/rules.d/91-local.rules
ACTION=="add", SUBSYSTEM=="usb", ATTR{product}=="USB Laser Mouse", ATTR{power/control}="on"

That didn’t stop the mouse from auto-suspending (and neither did “Logitech USB Laser Mouse” instead of “USB Laser Mouse”), so I tried creating a Udev rule specifying the Vendor ID and Product ID of the mouse:

# cat /etc/udev/rules.d/91-local.rules
ACTION=="add", SUBSYSTEM=="usb", ATTRS{idVendor}=="046d", ATTR{idProduct}=="c052", TEST=="power/control", ATTR{power/control}="on"

That didn’t stop the mouse from auto-suspending either.

Then I remembered that laptop-mode-tools is installed on my laptop:

# eix laptop-mode-tools
[I] app-laptop/laptop-mode-tools
Available versions: 1.60-r1 (~)1.62-r1 {(+)acpi apm bluetooth scsi}
Installed versions: 1.62-r1(18:10:15 11/01/13)(acpi bluetooth -apm -scsi)
Homepage: http://www.samwel.tk/laptop_mode/
Description: Linux kernel laptop_mode user-space utilities

So then I tried adding the mouse model to the blacklist in /etc/laptop-mode/conf.d/usb-autosuspend.conf by making AUTOSUSPEND_USBID_BLACKLIST="046d:c052" as shown below:

#
# Configuration file for Laptop Mode Tools module usb-autosuspend.
#
# For more information, consult the laptop-mode.conf(8) manual page.
#


###############################################################################
# USB autosuspend settings
# ------------------------
#
# If you enable this setting, laptop mode tools will automatically enable the
# USB autosuspend feature for all devices.
#
# NOTE: Some USB devices claim they support autosuspend, but implement it in a
# broken way. This can mean keyboards losing keypresses, or optical mice turning
# their LED completely off. If you have a device that misbehaves, add its USB ID
# to the blacklist below and complain to your hardware vendor.
################################################################################

# Enable debug mode for this module
# Set to 1 if you want to debug this module
DEBUG=0

# Enable USB autosuspend feature?
# Set to 0 to disable
CONTROL_USB_AUTOSUSPEND="auto"

# Set this to use opt-in/whitelist instead of opt-out/blacklist for deciding
# which USB devices should be autosuspended.
# AUTOSUSPEND_USE_WHITELIST=0 means AUTOSUSPEND_*_BLACKLIST will be used.
# AUTOSUSPEND_USE_WHITELIST=1 means AUTOSUSPEND_*_WHITELIST will be used.
AUTOSUSPEND_USE_WHITELIST=0

# The list of USB IDs that should not use autosuspend. Use lsusb to find out the
# IDs of your USB devices.
# Example: AUTOSUSPEND_USBID_BLACKLIST="046d:c025 0123:abcd"
AUTOSUSPEND_USBID_BLACKLIST="046d:c052"

# The list of USB driver types that should not use autosuspend.  The driver
# type is given by "DRIVER=..." in a USB device's uevent file.
# Example: AUTOSUSPEND_USBID_BLACKLIST="usbhid usb-storage"
AUTOSUSPEND_USBTYPE_BLACKLIST=""

# The list of USB IDs that should use autosuspend. Use lsusb to find out the
# IDs of your USB devices.
# Example: AUTOSUSPEND_USBID_WHITELIST="046d:c025 0123:abcd"
AUTOSUSPEND_USBID_WHITELIST=""

# The list of USB driver types that should use autosuspend.  The driver
# type is given by "DRIVER=..." in a USB device's uevent file.
# Example: AUTOSUSPEND_USBTYPE_WHITELIST="usbhid usb-storage"
AUTOSUSPEND_USBTYPE_WHITELIST=""

# Trigger auto-suspension of the USB deivce under conditional circumstances
BATT_SUSPEND_USB=1
LM_AC_SUSPEND_USB=0
NOLM_AC_SUSPEND_USB=0

# USB Auto-Suspend timeout in seconds
# Number of seconds after which the USB devices should suspend
AUTOSUSPEND_TIMEOUT=2

And now the mouse no longer suspends when I unplug the PSU:

# # PSU is currently connected.
# for d in /sys/bus/usb/devices/[0-9]* ; do if [[ -e $d/product ]] ; then echo -e "`basename $d`\t`cat $d/power/control`\t`cat $d/speed`\t`cat $d/product`" ; fi ; done
1-1.2 on 1.5 USB Laser Mouse
1-1.3 on 12 BCM2046 Bluetooth Device
2-1.2 on 12 Fingerprint Sensor
2-1.3 on 480 USB 2.0 Camera
2-1.6 on 1.5 USB Keyboard
# # Now I will disconnect the PSU...
# # PSU is currently disconnected.
# for d in /sys/bus/usb/devices/[0-9]* ; do if [[ -e $d/product ]] ; then echo -e "`basename $d`\t`cat $d/power/control`\t`cat $d/speed`\t`cat $d/product`" ; fi ; done
1-1.2 on 1.5 USB Laser Mouse
1-1.3 auto 12 BCM2046 Bluetooth Device
2-1.2 auto 12 Fingerprint Sensor
2-1.3 auto 480 USB 2.0 Camera
2-1.6 auto 1.5 USB Keyboard
# # Now I will reconnect the PSU...
# # PSU is currently connected.
# for d in /sys/bus/usb/devices/[0-9]* ; do if [[ -e $d/product ]] ; then echo -e "`basename $d`\t`cat $d/power/control`\t`cat $d/speed`\t`cat $d/product`" ; fi ; done
1-1.2 on 1.5 USB Laser Mouse
1-1.3 on 12 BCM2046 Bluetooth Device
2-1.2 on 12 Fingerprint Sensor
2-1.3 on 480 USB 2.0 Camera
2-1.6 on 1.5 USB Keyboard
#

So configuring laptop-mode-tools solved the problem with the mouse. Mind you, I will probably simply make CONTROL_USB_AUTOSUSPEND="no" in /etc/laptop-mode/conf.d/usb-autosuspend.conf, as I don’t want the internal USB devices in my laptop (Bluetooth adapter, fingerprint sensor and Webcam) to auto-suspend either.

UPDATE October 22, 2014: Version 1.65 and upwards of Laptop Mode Tools functions in a different way to earlier versions, so please see my post Laptop Mode Tools revisited due to a change in its functionality regarding the new way of configuring Laptop Mode Tools to stop USB devices auto-suspending.