[maemo-developers] Supporting external screen: kdrive with sisusbvga

[From: Graham Cobb]

As not everyone watches maemo-users I thought I would mention my request 
here...

There has recently been a discussion on maemo-users about attaching an 
external (VGA) screen.  I mentioned in that discussion that I have attached a 
StarTech.com USB 2.0 to VGA Display Adapter (model USB2VGA2) to my N810  
built the sisusbvga.ko driver and loaded it and it works!  Which means, I can 
display pictures on a VGA screen using the "sisbit" test program.

However, I would like to get some sort of dynamic display working.  I am 
considering three options at the moment:

1) Build a full xf86 xserver for Maemo.  There is an existing xf86 driver for 
the sisusbvga so this should work.  But I guess the xserver will be rather 
big and heavy for the tablet environment, and it may also require porting a 
load of dependencies.  So, I am not keen on this approach.

2) Create a kdrive driver for sisusbvga.  This is harder than I thought as 
most of the existing kdrive drivers are framebuffer based and sisusbvga 
doesn't provide a framebuffer.  Not helped by the fact that I know nothing 
about kdrive.

3) Create a simple vnc client which writes to the sisusbvga device and either 
vnc serve the tablet display or create a kdrive-based fake xdisplay which can 
be vnc-served.  The seems a bit convoluted but may end up the simplest from a 
development point of view.  It also avoids worrying about what to do about 
the input side of an X-server.

Is anyone else looking at this? Any thoughts or comments would be welcome.  
Code would be even more welcome!

Graham