Mesa (master): anv: Only enable EWA LOD algorithm when doing anisotropic filtering.

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Module: Mesa
Branch: master
Commit: defb3a9465bcdfbe691e5e7a785b9999fa77b500
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=defb3a9465bcdfbe691e5e7a785b9999fa77b500

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Mon Dec 16 21:15:15 2019 -0800

anv: Only enable EWA LOD algorithm when doing anisotropic filtering.

Updated documentation renames "Anisotropic Algorithm" to "LOD Algorithm"
and adds a note for Gen9+ saying "The EWA Algorithm should only be
enabled for Anisotropic Filtering modes." and indicating that the extra
accuracy shouldn't be necessary for other modes, and comes at a cost.

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

---

 src/intel/vulkan/genX_state.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/intel/vulkan/genX_state.c b/src/intel/vulkan/genX_state.c
index 34c6c6bd142..78e018762cb 100644
--- a/src/intel/vulkan/genX_state.c
+++ b/src/intel/vulkan/genX_state.c
@@ -506,7 +506,8 @@ VkResult genX(CreateSampler)(
          .MagModeFilter = vk_to_gen_tex_filter(mag_filter, pCreateInfo->anisotropyEnable),
          .MinModeFilter = vk_to_gen_tex_filter(min_filter, pCreateInfo->anisotropyEnable),
          .TextureLODBias = anv_clamp_f(pCreateInfo->mipLodBias, -16, 15.996),
-         .AnisotropicAlgorithm = EWAApproximation,
+         .AnisotropicAlgorithm =
+            pCreateInfo->anisotropyEnable ? EWAApproximation : LEGACY,
          .MinLOD = anv_clamp_f(pCreateInfo->minLod, 0, 14),
          .MaxLOD = anv_clamp_f(pCreateInfo->maxLod, 0, 14),
          .ChromaKeyEnable = 0,