Scanning in GuixSD

[Christopher Lemmer Webber]

Hello all,

I'm trying to get my scanner to work in GuixSD.  I can see it show up in
dmesg when I plug it in:

[    1.316145] usb 3-1: New USB device found, idVendor=04a9, idProduct=220e
[    1.316934] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[    1.317707] usb 3-1: Product: CanoScan
[    1.318472] usb 3-1: Manufacturer: Canon

However when I open simple-scan, it says no scanners found.  It sounds
like others have been able to scan just fine in GuixSD, so I wonder what
I'm missing?

Here's the possibly-relevant parts:

  (operating-system
    (host-name "oolong")
    (timezone "America/Chicago")
    (locale "en_US.UTF-8")
    ;; ...
  
    (users (cons (user-account
                  (name "cwebber")
                (uid 1000)
                  (comment "Christopher Lemmer Webber")
                  (group "cwebber")
                  (supplementary-groups '("users"
                                        "wheel" "netdev"
                                          "audio" "video" "input"))
                  (home-directory "/home/cwebber"))
                 %base-user-accounts))
  
    (groups (cons (user-group
                 (name "cwebber")
                 (id 1000))
                %base-groups))
  
    ;; Add Xfce and Ratpoison; that allows us to choose
    ;; sessions using either of these at the log-in screen.
    (packages (cons* xfce    ;desktop environments
                     sbcl-stumpwm+slynk
                     gnome
                     guile-wm
                     nss-certs         ;for HTTPS access
                     pulseaudio
                     postgresql
                     xf86-input-wacom
                     libwacom
                     xscreensaver
                     sane-backends
                     eudev
                     simple-scan
                     rsync
                     hplip             ;for cups and hp printers
                     cups-filters
                     %base-packages))
  
    ;; Use the "desktop" services, which include the X11
    ;; log-in service, networking with Wicd, and more.
    (services (cons*
               (postgresql-service)
               (screen-locker-service xscreensaver)
               ssh-service
               cups-service
               thermald-service
               (extra-special-file "/usr/bin/env"
                                   (file-append coreutils "/bin/env"))
               (modify-services %desktop-services
                                (slim-service-type
                                 config => (slim-configuration
                                            (inherit config)
                                            (startx (xorg-start-command
                                                     #:configuration-file
                                                     (xorg-configuration-file
                                                      #:drivers 
'("intel"))))))))))

Thanks!
 - Chris