This is what I did to get my Raspberry Pi working on my Lapdock 500 pro. I did have to modify a usb cable and make some changes to the config.txt file so proceed with caution.
I used an HDMI gender changer that I got from an individual on ebay without any kind of packaging so I don't know what brand it is, sorry.
Here is the bar code of the micro HDMI to HDMI cable i got. 681131027441 It says it is high speed with ethernet on the package.
The usb cable was kind of tricky because when I got the female micro usb adapter it only had a red and a black wire in it.
Here is the female micro usb end that I soldered to an old usb cable.
Red was already on 1 and black was already on 5. I soldered white to 2. Green to 3. I had to add a solder bridge between 4 and 5. *Edit* DISCONNECT THE RED WIRE FROM 1!!!
I just cut the red wire in the casing but do it however you like. If you don't the Pi will be getting 5v from the wall and 4.?v back fed from the Lapdock.
Preparing the Pi
I used the config.txt from this page https://raw.github.com/Evilpaul/RPi-con ... config.txt
Edited it so I had hdmi_force_hotplug=1, hdmi_drive=2, hdmi_mode=86, and disable_overscan=1 uncommented.
I booted the Pi on a regular monitor, went into raspi-config, overclocked the Pi to 950, enabled the camera, and made sure it boots to the desktop. (I don't know why this matters but I can't get the Lapdock to turn on with out it.)
Connecting the Pi to the Lapdock
1. Make sure the Lapdock is charged but not plugged into the wall.
2. Connect the HDMI and USB cable to the PI
3. Plug the Pi into the wall. (Make sure the Pi has enough time to boot to the desktop.)
4. Open the Lapdock.
5. Connect the micro USB to the Lapdock.
6. Connect the HDMI to the Lapdock using the HDMI gender changer.
This is the part where strange things start happening with the Lapdock not turning on all of the time. So I will put a couple methods here.
7a. After the power light flashes on then off unplug the HDMI from anywhere and plug it back in.
8a. If the screen flashes on, it will go off and come back on with the desktop.
If that doesn't work then try this.
7b. After the power light flashes on then off unplug the HDMI and power from the Pi
8b. If the screen flashes on quickly plug the HDMI and power back into the pi.
The Lapdock doesn't play well with others so you might have to try it a few times to get it going. I've done the same thing over and over and gotten different results so maybe someone can come up with a more consistent method.
One other thing I should add. If you are using a WiPi, plug it into the Pi. When the Pi goes to sleep the Lapdock won't wake up the WiPi and you are stuck going through the whole sequence again.