[Mesa-dev] [PATCH 1/6] i965/gen4: Work around missing sRGB RGB DXT1 support.

[Kenneth Graunke]

On 02/06/2013 05:29 PM, Eric Anholt wrote:
> The hardware just doesn't support it.  I suspect this was a regression from
> the move to fixed MESA_FORMATs for compressed textures and that previously we
> were storing uncompressed for this or something.
>
> Fixes GPU hangs in piglit "texwrap GL_EXT_texture_sRGB-s3tc bordercolor
> swizzled" on my GM965.
> ---
>   src/mesa/drivers/dri/i965/brw_state.h             |    3 ++-
>   src/mesa/drivers/dri/i965/brw_wm_surface_state.c  |   18 ++++++++++++++++--
>   src/mesa/drivers/dri/i965/gen7_wm_surface_state.c |    3 ++-
>   3 files changed, 20 insertions(+), 4 deletions(-)

This is obviously better than GPU hanging, but I wonder if we could 
instead fallback to SRGBA_DXT1 or just SRGB.  But I suppose that can be 
a later improvement (first no hangs, then correctness, ...)

Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

> diff --git a/src/mesa/drivers/dri/i965/brw_state.h b/src/mesa/drivers/dri/i965/brw_state.h
> index adc64e3..ecc61c4 100644
> --- a/src/mesa/drivers/dri/i965/brw_state.h
> +++ b/src/mesa/drivers/dri/i965/brw_state.h
> @@ -197,7 +197,8 @@ uint32_t brw_format_for_mesa_format(gl_format mesa_format);
>
>   GLuint translate_tex_target(GLenum target);
>
> -GLuint translate_tex_format(gl_format mesa_format,
> +GLuint translate_tex_format(struct intel_context *intel,
> +                            gl_format mesa_format,
>   			    GLenum internal_format,
>   			    GLenum depth_mode,
>   			    GLenum srgb_decode);
> 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 f8251b2..8ed7c3d 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> @@ -622,7 +622,8 @@ brw_render_target_supported(struct intel_context *intel,
>   }
>
>   GLuint
> -translate_tex_format(gl_format mesa_format,
> +translate_tex_format(struct intel_context *intel,
> +                     gl_format mesa_format,
>   		     GLenum internal_format,
>   		     GLenum depth_mode,
>   		     GLenum srgb_decode)
> @@ -651,6 +652,17 @@ translate_tex_format(gl_format mesa_format,
>          */
>         return BRW_SURFACEFORMAT_R32G32B32A32_FLOAT;
>
> +   case MESA_FORMAT_SRGB_DXT1:
> +      if (intel->gen == 4 && !intel->is_g4x) {
> +         /* Work around missing SRGB DXT1 support on original gen4 by just
> +          * skipping SRGB decode.  It's not worth not supporting sRGB in
> +          * general to prevent this.
> +          */
> +         WARN_ONCE(true, "Demoting sRGB DXT1 texture to non-sRGB\n");
> +         mesa_format = MESA_FORMAT_RGB_DXT1;
> +      }
> +      return brw_format_for_mesa_format(mesa_format);
> +
>      default:
>         assert(brw_format_for_mesa_format(mesa_format) != 0);
>         return brw_format_for_mesa_format(mesa_format);
> @@ -829,6 +841,7 @@ brw_update_texture_surface(struct gl_context *ctx,
>                              uint32_t *binding_table,
>                              unsigned surf_index)
>   {
> +   struct intel_context *intel = intel_context(ctx);
>      struct brw_context *brw = brw_context(ctx);
>      struct gl_texture_object *tObj = ctx->Texture.Unit[unit]._Current;
>      struct intel_texture_object *intelObj = intel_texture_object(tObj);
> @@ -852,7 +865,8 @@ brw_update_texture_surface(struct gl_context *ctx,
>      surf[0] = (translate_tex_target(tObj->Target) << BRW_SURFACE_TYPE_SHIFT |
>   	      BRW_SURFACE_MIPMAPLAYOUT_BELOW << BRW_SURFACE_MIPLAYOUT_SHIFT |
>   	      BRW_SURFACE_CUBEFACE_ENABLES |
> -	      (translate_tex_format(mt->format,
> +	      (translate_tex_format(intel,
> +                                    mt->format,
>   				    firstImage->InternalFormat,
>   				    tObj->DepthMode,
>   				    sampler->sRGBDecode) <<
> diff --git a/src/mesa/drivers/dri/i965/gen7_wm_surface_state.c b/src/mesa/drivers/dri/i965/gen7_wm_surface_state.c
> index 179024a..d53df20 100644
> --- a/src/mesa/drivers/dri/i965/gen7_wm_surface_state.c
> +++ b/src/mesa/drivers/dri/i965/gen7_wm_surface_state.c
> @@ -309,7 +309,8 @@ gen7_update_texture_surface(struct gl_context *ctx,
>                                       8 * 4, 32, &binding_table[surf_index]);
>      memset(surf, 0, 8 * 4);
>
> -   uint32_t tex_format = translate_tex_format(mt->format,
> +   uint32_t tex_format = translate_tex_format(intel,
> +                                              mt->format,
>                                                 firstImage->InternalFormat,
>                                                 tObj->DepthMode,
>                                                 sampler->sRGBDecode);
>