Is there the possibility to support EXA for legacy S3 chips?

[Alex Deucher]

On Wed, May 27, 2009 at 5:09 PM, Evgeny M. Zubok <evgeny.zubok at tochka.ru> wrote:
>
> I have made the first attempt to implement basic `Copy' and `Solid' EXA
> functions in xf86-video-s3, but soon came to intention that EXA support
> is not possible. Is there mistake in my thinking below?
>
> S3's Graphic Processor (S3 GP) is able to copy areas only in terms of
> coordinates, i. e. it can copy rectangle from (src-x, src-y) to (dest-x,
> dest-y) with width w and height h (Fig. 1). This method is used in XAA
> ScreenToScreenCopy function. But S3 GP hasn't mean to copy offscreen
> pixmaps in format presented on Fig. 2 to framebuffer, i. e. there is no
> way to write the pixmap's offset and pitch directly into GP registers to
> make subsequent copying. I looked up on the code of few other drivers
> where EXA is implemented (ati, trident, mga) -- all these chips have the
> possibility to write offset and pitch of pixmap into their GP.
>
> Although the method (by means of Pixel Transfer Register) exists to
> upload pixmap from the system memory to S3's offscreen memory in
> required format (Fig. 1) (I didn't try it), such offscreen memory
> organization will not be understandable to the EXA offscreen memory
> manager. Most probably this will follow to incorrect pixmap migration
> and overwriting previously uploaded pixmaps.
>
> The objection above sounds like the judgement to EXA support in S3
> driver. No?

Looks like no dice for EXA.  Fixed pitches, no offsets... ouch.

Alex