[Mesa-dev] [PATCH 3/3] i965/sampler_state: Set the "Base Mip Level" field on Sandy Bridge

[Lionel Landwerlin]

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>

On 10/02/17 23:52, Jason Ekstrand wrote:
> Fixes two GL ES 3.0 CTS tests on Sandy Bridge:
>
> ES3-CTS.functional.texture.mipmap.cube.base_level.linear_linear
> ES3-CTS.functional.texture.mipmap.cube.base_level.linear_nearest
>
> Cc: "17.0 13.0" <mesa-stable at lists.freedesktop.org>
> ---
>   src/mesa/drivers/dri/i965/brw_sampler_state.c | 20 +++++++++++++++++++-
>   src/mesa/drivers/dri/i965/brw_state.h         |  1 +
>   2 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/i965/brw_sampler_state.c b/src/mesa/drivers/dri/i965/brw_sampler_state.c
> index 1cf10a8..b99a898 100644
> --- a/src/mesa/drivers/dri/i965/brw_sampler_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_sampler_state.c
> @@ -88,6 +88,7 @@ brw_emit_sampler_state(struct brw_context *brw,
>                          unsigned wrap_s,
>                          unsigned wrap_t,
>                          unsigned wrap_r,
> +                       unsigned base_level,
>                          unsigned min_lod,
>                          unsigned max_lod,
>                          int lod_bias,
> @@ -132,6 +133,21 @@ brw_emit_sampler_state(struct brw_context *brw,
>         ss[0] |= SET_FIELD(lod_bias & 0x7ff, GEN4_SAMPLER_LOD_BIAS) |
>                  SET_FIELD(shadow_function, GEN4_SAMPLER_SHADOW_FUNCTION);
>   
> +      /* This field has existed since the original i965, but is declared MBZ
> +       * until Sandy Bridge.  According to the PRM:
> +       *
> +       *    "This was added to match OpenGL semantics"
> +       *
> +       * In particular, OpenGL allowed you to offset by 0.5 in certain cases
> +       * to get slightly better filtering.  On Ivy Bridge and above, it
> +       * appears that this is added to RENDER_SURFACE_STATE::SurfaceMinLOD so
> +       * the right value is 0.0 or 0.5 (if you want the wacky behavior).  On
> +       * Sandy Bridge, however, this sum does not seem to occur and you have
> +       * to set it to the actual base level of the texture.
> +       */
> +      if (brw->gen == 6)
> +         ss[0] |= SET_FIELD(base_level, BRW_SAMPLER_BASE_MIPLEVEL);
> +
>         if (brw->gen == 6 && min_filter != mag_filter)
>            ss[0] |= GEN6_SAMPLER_MIN_MAG_NOT_EQUAL;
>   
> @@ -503,6 +519,8 @@ brw_update_sampler_state(struct brw_context *brw,
>   
>      const int lod_bits = brw->gen >= 7 ? 8 : 6;
>      const float hw_max_lod = brw->gen >= 7 ? 14 : 13;
> +   const unsigned base_level =
> +      U_FIXED(CLAMP(texObj->MinLevel + texObj->BaseLevel, 0, hw_max_lod), 1);
>      const unsigned min_lod =
>         U_FIXED(CLAMP(sampler->MinLod, 0, hw_max_lod), lod_bits);
>      const unsigned max_lod =
> @@ -532,7 +550,7 @@ brw_update_sampler_state(struct brw_context *brw,
>                             max_anisotropy,
>                             address_rounding,
>                             wrap_s, wrap_t, wrap_r,
> -                          min_lod, max_lod, lod_bias,
> +                          base_level, min_lod, max_lod, lod_bias,
>                             shadow_function,
>                             non_normalized_coords,
>                             border_color_offset);
> diff --git a/src/mesa/drivers/dri/i965/brw_state.h b/src/mesa/drivers/dri/i965/brw_state.h
> index 36307c7..4b7e3c2 100644
> --- a/src/mesa/drivers/dri/i965/brw_state.h
> +++ b/src/mesa/drivers/dri/i965/brw_state.h
> @@ -335,6 +335,7 @@ void brw_emit_sampler_state(struct brw_context *brw,
>                               unsigned wrap_s,
>                               unsigned wrap_t,
>                               unsigned wrap_r,
> +                            unsigned base_level,
>                               unsigned min_lod,
>                               unsigned max_lod,
>                               int lod_bias,