[Libdlo] USB Displaylink device

J.B. Brown jbbrown at pharm.kyoto-u.ac.jp
Wed Sep 7 17:19:36 PDT 2011

Hello everyone and thank you for your time.
I am trying to use a USB DisplayLink monitor provided by the company Century.
The model is a LCD-10000U, and is DisplayLink certified
(http://www.displaylink.com/shop/index.php?product=2, manufacturer
link http://www.jpcentury.com/pro_con.aspx?id=P_00000040).

Using Fedora 14 (Gnome 2) and kernel 2.6.35, I built the 3.0.4 kernel
with DisplayLink support.
After booting the kernel, I attach the device.
The identification of the USB device is successful, and the udlfb
driver recognizes the device.

However, the display doesn't function.
It currently shows a series of diagonal lines, which I (probably
incorrectly) speculate is simply a dump of the last data in the
display's framebuffer.

So it seems that "I'm in the ballpark", but I either don't have my
Xserver setup correctly or I need to modify something else to get it
to work.
I know the device works fine, since I tested its functionality using
the included driver for MS Windows 7.
(No official Linux support.)

I am attaching the output of dmesg and a list of loaded modules as
reported by Xorg.
The part of the dmesg output that catches my attention is the
following two lines:
[   81.486356] udlfb: console enable=0
[   81.486359] udlfb: fb_defio enable=0
Also, I don't see a DisplayLink-specific module being loaded by Xorg.
However, I don't know if I'm thinking incorrectly about my problem.

While I write application code and am comfortable with system
administration, I am not a kernel or hardware driver developer (though
I am really interested in contributing).
Any leads, opinions, or ideas about how to get this device to work
would be really appreciated.
Thanks everyone.

J.B. Brown, Ph.D.
Kyoto University Graduate School of Pharmaceutical Sciences

--dmesg output begin--
[   80.881198] usb 2-3: new high speed USB device number 3 using ehci_hcd
[   81.000048] usb 2-3: New USB device found, idVendor=17e9, idProduct=403e
[   81.000060] usb 2-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[   81.000067] usb 2-3: Product: LCD-10000U
[   81.000073] usb 2-3: Manufacturer: DisplayLink
[   81.000079] usb 2-3: SerialNumber: 1004415
[   81.003524] generic-usb 0003:17E9:403E.0001: hiddev0,hidraw0: USB
HID v1.10 Device [DisplayLink LCD-10000U] on usb-0000:00:1d.7-3/input1
[   81.486344] udlfb: DisplayLink LCD-10000U - serial #1004415
[   81.486352] udlfb: vid_17e9&pid_403e&rev_0103 driver's dlfb_data
struct at ffff88011c6ab800
[   81.486356] udlfb: console enable=0
[   81.486359] udlfb: fb_defio enable=0
[   81.486559] udlfb: vendor descriptor length:23 data:23 5f 01 0021
00 04 04 07 00 01
[   81.486565] udlfb: DL chip limited to 2080000 pixel modes
[   81.486819] udlfb: allocated 4 65024 byte urbs
[   81.567019] udlfb: 1366x768 valid mode
[   81.567025] udlfb: Reallocating framebuffer. Addresses will change!
[   81.568764] udlfb: 1366x768 valid mode
[   81.568769] udlfb: set_par mode 1366x768
[   81.570908] udlfb: DisplayLink USB device /dev/fb2 attached.
1366x768 resolution. Using 4104K framebuffer memory
[   81.570951] usbcore: registered new interface driver udlfb
[jbbrown at jbbrown]~% uname --all
Linux jbbrown.laptop 3.0.4 #1 SMP Thu Sep 8 06:16:22 JST 2011 x86_64
x86_64 x86_64 GNU/Linux
---dmesg output end

---xorg loaded modules---
[jbbrown at jbbrown]/var/log% grep LoadModule Xorg.0.log
[    30.070] (II) LoadModule: "extmod"
[    30.071] (II) LoadModule: "dbe"
[    30.072] (II) LoadModule: "glx"
[    30.330] (II) LoadModule: "record"
[    30.331] (II) LoadModule: "dri"
[    30.332] (II) LoadModule: "dri2"
[    30.333] (II) LoadModule: "intel"
[    30.333] (II) LoadModule: "vesa"
[    30.334] (II) LoadModule: "fbdev"
[    30.336] (II) LoadModule: "fbdevhw"
[    30.406] (II) LoadModule: "fb"
[    30.872] (II) LoadModule: "evdev"
[    30.943] (II) LoadModule: "synaptics"

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