siliconmotion driver hacking [xf86-video-siliconmotion-1.7.4]

[Frith Foottit]

Hi peeps.

I hope you guys don't mind the occasional newbie question :)

I have a vaguely interesting 'problem' regarding the siliconmotion
driver (the system is running Xubuntu 9.10 at the moment) and before I
start hacking around with the source code I thought I might ask if
there is someone more involved with this module that could possibly
give me some pointers or help me avoid some pitfalls.

What I would like to do is compile a 'portrait' video driver.
Essentially, I think I just want to swap the x and y values for each
pixel, thus creating an output for a display in portrait mode.

The reason I don't want to use the framebuffer for this is that the
old tablet pc (Acer c100) I want to use it on is unusably slow when
using the FB - the 800MHz processor jus' can't take it cap'n. Ideally
I would like to be able to select from the normal or the rotated
driver (doing this at boot time is fine) so I can use the computer in
either mode (baby steps...)

I figure that there is a bit more to it than just doing a global
"replace data_x with data_y and change screen resolutions to 600x800",
but is there any show stopper that would prevent a plan like this
working? I guess I would lose the hardware video decoding, but aside
from that this idea could work, right?

Cheers,

Frith.