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

Alex Deucher alexdeucher at
Mon Nov 15 07:56:39 PST 2010

On Mon, Nov 15, 2010 at 3:33 AM, Frith Foottit <frith.foottit at> wrote:
> 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?

IIRC, the siliconmotion driver in git already supports hw accelerated
rotation using randr if you use EXA.


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