[Mesa-dev] [PATCH 3/4] tnl: Maintain the _WindowMap matrix in TNLcontext v2.

[Ilia Mirkin]

On Fri, Aug 7, 2015 at 2:46 AM, Mathias Fröhlich <Mathias.Froehlich at gmx.net>
wrote:

>
>
> Hi,
>
>
>
> On Thursday, August 06, 2015 12:32:18 Ilia Mirkin wrote:
>
> > > @@ -182,6 +187,13 @@ _tnl_InvalidateState( struct gl_context *ctx,
> GLuint new_state )
>
> > > }
>
> > > }
>
> > > }
>
> > > +
>
> > > + if (new_state & (_NEW_VIEWPORT | _NEW_BUFFERS)) {
>
> > > + double scale[3], translate[3];
>
> > > + _mesa_get_viewport_xform(ctx, 0, scale, translate);
>
> > > + _math_matrix_viewport(&tnl->_WindowMap, scale, translate,
>
> > > + ctx->DrawBuffer->_DepthMaxF);
>
> >
>
> > This appears to crash nouveau_vieux on startup. See
>
> > https://bugs.freedesktop.org/show_bug.cgi?id=91570 . I suspect that
>
> > ctx->DrawBuffer is null. What's the proper way to handle that
>
> > situation -- predicate on a drawbuffer being bound? Or make sure that
>
> > something is bound to the drawbuffer before we call tnl_wakeup?
>
> >
>
>
>
> It looks like nouveau_vieux uses _tnl_InvalidateState for early
> initialization.
>
> I assume that _mesa_make_current is called later on to set the DrawBuffer
>
> and there the _NEW_BUFFERS flag is set. So, when _tnl_InvalidateState is
> called
>
> while validating state before the first draw and past a bound draw buffer,
> we should
>
> get the desired update on the _WindowMap matrix.
>
> So just checking for the presence of the DrawBuffer before grabbing data
>
> from it seems to be safe.
>
>
>
> The aim of the change was to move the _WindowMap matrix out of the non tnl
> drivers
>
> and track it in the tnl module where it is exclusively used today.
>
> At the higher mesa level we did/do not invalidate DrawBuffer related state
> that early.
>
>
>
> One alternative I can see is to call _tnl_InvalidateState without the
> _NEW_VIEWPORT and
>
> _NEW_BUFFERS flag set instead of _tnl_wakeup in the two nouveau early
> initialization
>
> code paths in nouveau_swtnl_t.c and nv04_render.c. That should also bring
> us back to
>
> the original behavior.
>

That seems like a bit of a hack. If you think it's OK, I'm just going to
introduce the DrawBuffer check. Brian, does that seem OK to you? I'm mostly
unfamiliar with the TnL module, its APIs, and when/how they're supposed to
be used. But nouveau_vieux calls tnl_wakeup right in its context creation
pass. nv04/nv05 don't have hwtnl at all, nv10+ have it, but it has various
limitations, with which we end up using swtnl.

  -ilia
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