i965: Enable EWA anisotropic filtering algorithm

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.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

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 (file)
--- 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,