[Mesa-dev] [PATCH 1/6] i965/state: Ignore intel_obj->_Format for depth/stencil and ETC2

[Chad Versace]

On Wed 24 Jan 2018, Jason Ekstrand wrote:
> We're about to start letting the intel_obj->_Format be the "real"
> texture format.  For depth/stencil textures, this may be a combined
> depth stencil format.  For ETC2 on gen7 and earlier, this will be the
> actual ETC2 format.  This makes a bit more GL sense but means we have to
> be careful in state upload.

What is the "real" format? It's not a rhetorical question. Throughout
Mesa, I never know what's real and what's not. By "real", do you mean
the untranslated user-specified glTextureView(internalformat) and
glTexImage2D(internalformat)?  Or do you mean simply "more real than
before" ;)

> ---
>  src/mesa/drivers/dri/i965/brw_wm_surface_state.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> index 38af6bc..844c23b 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> @@ -507,7 +507,21 @@ brw_update_texture_surface(struct gl_context *ctx,
>        const unsigned swizzle = (unlikely(alpha_depth) ? SWIZZLE_XYZW :
>                                  brw_get_texture_swizzle(&brw->ctx, obj));
>  
> -      mesa_format mesa_fmt = plane == 0 ? intel_obj->_Format : mt->format;
> +      mesa_format mesa_fmt;
> +      if (firstImage->_BaseFormat == GL_DEPTH_STENCIL ||
> +          firstImage->_BaseFormat == GL_DEPTH_COMPONENT) {
> +         /* The format from intel_obj may be a combined depth stencil format
> +          * when we just want depth.  Pull it from the miptree instead.  This
> +          * is safe because texture views aren't allowed on depth/stencil.
> +          */
> +         mesa_fmt = mt->format;
> +      } else if (mt->etc_format != MESA_FORMAT_NONE) {
> +         mesa_fmt = mt->format;

This looks like it would break ETC2 texture views on hw where we decode
the ETC2 on upload (Ivybridge?), if such views worked. I suspect such
texture views never worked.

> +      } else if (plane > 0) {
> +         mesa_fmt = mt->format;
> +      } else {
> +         mesa_fmt = intel_obj->_Format;
> +      }
>        enum isl_format format = translate_tex_format(brw, mesa_fmt,
>                                                      for_txf ? GL_DECODE_EXT :
>                                                      sampler->sRGBDecode);

I want to give a r-b, but want to first hear your reply regarding the
"real" format.