[Savage40] Twister T Problems

[Andrew Roca]

Hello


I've been working on a system which uses a Twister T north bridge /
graphics controller and I've encountered some problems with the X server
driver. 

The applications we have in mind need good graphics performance ( many
of them will be games), so I've been looking around for the driver set
that will offer the best performance for both 2D and 3D applications.

The standard driver that has current been included with the Xserver
(I've tried both XF86 and Xorg Xserver packages) are very stable but the
performance is disappointing below what we need.

I have tried both the VIA authored (modified ?) driver on XF86 4.2 and
the current driver offered by the DRI project and in both cases I
encounter the same problem. I can get everything to work except the 2D
dga interface for depths greater than 8 bits. The dga code is called via
the SDL library and works on other platforms, however if I request a 16
bit fullscreen hardware surface, all the calls succeed but the resultant
screen image is very badly corrupted.  

The image seems broken up into small rectangles say 8 or 16 pixels on
each side.

In searching the web I haven't see anybody else report this problem
although I did find some diff files on Alex Deucher's web site that
modified the memory stride used by the driver in the case of the
twister,and this might explain the corruption I'm seeing.

The other approach I considered was that BIOS was getting the video mode
switch wrong, but this seems unlikly as I can set the model correctly
via an OpenGL SDL interface and the normal Xserver works fine. 

Another thing that worries me is the question of device identification,
lspci reports the device as a 86C380 [ProSavage DDR K4M266] rev 02.

But the device should be a VT8603C PN 133 and is labelled a twister t on
the devices package.

The Northbridge and video PCI idents are 5333 8d01 and 1106 8605.

I must confess to a certain confusion to the differences between all the
different models.

I would be grateful for any help, this problem has been bugging me for
sometime now and I'm afraid my knowledge of Xserver internals isn't
great.

Thanks

Andrew Roca