nv 2.1.x: why no acceleration with RandR rotation enabled and screen not rotated?

[Alex Deucher]

On 9/25/07, Giuseppe Bilotta <giuseppe.bilotta at gmail.com> wrote:
> On 9/25/07, Alex Deucher <alexdeucher at gmail.com> wrote:
> > On 9/25/07, Giuseppe Bilotta <giuseppe.bilotta at gmail.com> wrote:
> > > On 9/25/07, Alex Deucher <alexdeucher at gmail.com> wrote:
> > > >
> > > > Acceleration in rotated modes requires exa composite support which is
> > > > not available in nv at the moment.
> > >
> > > Thanks, this explains why I shouldn't get accelerated output when the
> > > screen is rotated, but why does nv disable acceleration tout court?
> > > couldn't it just disable it just when the screen is actually rotated?
> >
> > It should just work; does on other drivers.  You'd have to ask Aaron
> > why nv works that way.
>
> Just for kicks I tried something very stupid (i.e. removing the line
> that sets NoAccel when RandR rotation is enabled). No spectular crash,
> but there seem to be serious framebuffer problems (large black botches
> all across the screen) even when the screen isn't rotated. I'll see if
> I can nail exactly what's going wrong.

It may have to do with tiling or some special FB format required for
acceleration.

Alex