[Mesa-dev] [PATCH] i965: Enable EWA anisotropic filtering algorithm

[Anuj Phogat]

On Tue, Mar 4, 2014 at 1:08 AM, Ian Romanick <idr at freedesktop.org> wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
>
> Volume 4, part 1 of the Ivybridge PRM says, "Generally, the EWA
> approximation algorithm results in higher image quality than the legacy
> algorithm."  Using a classic anisotropic filtering "tunnel" demo, it
> appears that there is *no* anisotropic filtering on IVB without this bit
> set.
So, the legacy algorithm for anisotropic filtering doesn't work. Do you
suspect a hardware bug?
>
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> Cc: Eero Tamminen <eero.t.tamminen at intel.com>
> ---
>  src/mesa/drivers/dri/i965/gen7_sampler_state.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/src/mesa/drivers/dri/i965/gen7_sampler_state.c b/src/mesa/drivers/dri/i965/gen7_sampler_state.c
> index 968c410..709a783 100644
> --- a/src/mesa/drivers/dri/i965/gen7_sampler_state.c
> +++ b/src/mesa/drivers/dri/i965/gen7_sampler_state.c
> @@ -82,6 +82,7 @@ gen7_update_sampler_state(struct brw_context *brw, int unit, int ss_index,
>     if (gl_sampler->MaxAnisotropy > 1.0) {
>        sampler->ss0.min_filter = BRW_MAPFILTER_ANISOTROPIC;
>        sampler->ss0.mag_filter = BRW_MAPFILTER_ANISOTROPIC;
> +      sampler->ss0.aniso_algorithm = 1;
>
>        if (gl_sampler->MaxAnisotropy > 2.0) {
>          sampler->ss3.max_aniso = MIN2((gl_sampler->MaxAnisotropy - 2) / 2,
> --
> 1.8.1.4
>
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Reviewed-by: Anuj Phogat <anuj.phogat at gmail.com>