[Mesa-dev] [PATCH 0/2] mesa/gallium: add NV_texture_barrier

[Marek Olšák]

On Fri, Mar 11, 2011 at 2:56 PM, Keith Whitwell <keithw at vmware.com> wrote:

> On Fri, 2011-03-11 at 06:05 +0100, Marek Olšák wrote:
> > Hi,
> >
> > these 2 patches add GL_NV_texture_barrier to Mesa and Gallium,
> > respectively. The extension can be used for programmable
> > blending, where the same texture can be bound as both a sampler
> > and renderbuffer. The same feature exists in Direct10 and
> > the entry point is:
> >
> > VOID APIENTRY ResourceReadAfterWriteHazard(
> >   __in  D3D10DDI_HDEVICE hDevice,
> >   __in  D3D10DDI_HRESOURCE hResource
> > )
> >
> > I have chosen the same name for Gallium:
> >
> > void (*resource_read_after_write_hazard)(struct pipe_context *,
> >                                          struct pipe_resource *)
> >
> > The function is documented in the second patch.
> > There is a new piglit test too, called blending-in-shader.
> > I only have working r300g support, but I may add softpipe
> > if needed.
>
> I support this goal, but think you've probably chosen the wrong name for
> the function.
>
> The call you're introducing is a method for the application to cooperate
> with the driver to get meaningful results when a single resource is
> bound for read & write at the same time.
>
> In DX10-land, ResourceReadAfterWriteHazard() is something generated
> internally by the runtime when a resource which was previously bound to
> write is being rebound to read from, ie. something like:
>
>   if (ctx->is_resource_referenced(ctx, resource))
>       ctx->flush(ctx);
>
> From their docs: "The ResourceReadAfterWriteHazard function informs the
> user-mode display driver that the specified resource was used as an
> output from the graphics processing unit (GPU) and that the resource
> will be used as an input to the GPU."
>
> And: "The Microsoft Direct3D runtime calls ResourceReadAfterWriteHazard
> immediately before the specified resource is bound as an input to the
> GPU."
>
> Binding a single subresource for reading and writing at the same time is
> (to my knowledge) not permitted in DX10.
>
> So my suggestion would be to name this something else, perhaps taking
> language from the NV extension.
>

Alright.

There are two patches attached in this email. The former is my attempt at
display list support that I missed. The latter changes the gallium entry
point to:

void (*texture_barrier)(struct pipe_context *);

Please review.

Best regards
Marek
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