Attachment 114246 Details for Bug 82463 – Patch 2/2

[patch] Patch 2/2

0002-i965-Enable-EWA-algorithm-in-IvyBridge-for-isotropic.patch (text/plain), 5.02 KB, created by Iago Toral on 2015-03-12 08:32:45 UTC

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Creator: Iago Toral

Created: 2015-03-12 08:32:45 UTC

Size: 5.02 KB

patch

obsolete

>From 67ea399fab0b984bfce23a19938709fd720137fd Mon Sep 17 00:00:00 2001
>From: Iago Toral Quiroga <itoral@igalia.com>
>Date: Wed, 11 Mar 2015 13:57:04 +0100
>Subject: [PATCH 2/2] i965: Enable EWA algorithm in IvyBridge for isotropic
> filters
>
>As per description in bug 82463 this improves image quality when using
>isotropic filters in some cases.
>
>However, this breaks many tex-miplevel-selection tests for textureGrad.
>This is explained in the Haswell PRM, which includes the following
>Programming Note:
>
>"When EWA (is) used for non-anisotropic filtering and the coordinates
>have zero derivative the computed LOD is 0 instead of -inf."
>
>This means that in certain situations the EWA algorithm, when used
>in isotropic scenarios, leads to incorrect LOD computations, and thus,
>incorrect rendering.
>
>For textureGrad, we can fix this by enabling the lowering we are
>currently using for shadow samplers, where we compute the LOD manually
>for the texture gradients. However, that will only fix textureGrad but
>the problem will still exist for other texture functions. This is clearly
>visible with the following piglit test that is regressed after fixing
>textureGrad:
>
>bin/arb_shader_texture_lod-texgrad -auto -fbo
>
>This test renders two samples using texture() and textureGrad() and
>expects both renderings to be the same. This patch breaks this because
>for the textureGrad case we are computing LOD manually, but in the
>texture case the hardware is computing the LOD and thus, is subject to
>incorrect LOD computations in some cases, which leads to noticeable
>differences in the way the texture is rendered.
>---
> src/mesa/drivers/dri/i965/brw_sampler_state.c | 17 ++++++++++++++---
> src/mesa/drivers/dri/i965/brw_state.h         |  3 ++-
> src/mesa/drivers/dri/i965/gen6_blorp.cpp      |  3 ++-
> 3 files changed, 18 insertions(+), 5 deletions(-)
>
>diff --git a/src/mesa/drivers/dri/i965/brw_sampler_state.c b/src/mesa/drivers/dri/i965/brw_sampler_state.c
>index c532850..7b205c2 100644
>--- a/src/mesa/drivers/dri/i965/brw_sampler_state.c
>+++ b/src/mesa/drivers/dri/i965/brw_sampler_state.c
>@@ -91,7 +91,8 @@ brw_emit_sampler_state(struct brw_context *brw,
>                        unsigned base_level,
>                        unsigned shadow_function,
>                        bool non_normalized_coordinates,
>-                       uint32_t border_color_offset)
>+                       uint32_t border_color_offset,
>+                       bool enable_ewa)
> {
>    ss[0] = BRW_SAMPLER_LOD_PRECLAMP_ENABLE |
>            SET_FIELD(base_level, BRW_SAMPLER_BASE_MIPLEVEL) |
>@@ -114,7 +115,7 @@ brw_emit_sampler_state(struct brw_context *brw,
>    if (brw->gen >= 7) {
>       ss[0] |= SET_FIELD(lod_bias & 0x1fff, GEN7_SAMPLER_LOD_BIAS);
> 
>-      if (min_filter == BRW_MAPFILTER_ANISOTROPIC)
>+      if (enable_ewa)
>          ss[0] |= GEN7_SAMPLER_EWA_ANISOTROPIC_ALGORITHM;
> 
>       ss[1] = SET_FIELD(min_lod, GEN7_SAMPLER_MIN_LOD) |
>@@ -444,6 +445,15 @@ brw_update_sampler_state(struct brw_context *brw,
>       }
>    }
> 
>+   /* Enable EWA algorithm for anisotropic filter and also
>+    * for isotropic case in IvyBridge
>+    */
>+   bool enable_ewa = false;
>+   if (min_filter == BRW_MAPFILTER_ANISOTROPIC ||
>+       (brw->gen == 7 && !brw->is_haswell)) {
>+      enable_ewa = true;
>+   }
>+
>    /* Set address rounding bits if not using nearest filtering. */
>    unsigned address_rounding = 0;
>    if (min_filter != BRW_MAPFILTER_NEAREST) {
>@@ -525,7 +535,8 @@ brw_update_sampler_state(struct brw_context *brw,
>                           min_lod, max_lod, lod_bias, base_level,
>                           shadow_function,
>                           non_normalized_coords,
>-                          border_color_offset);
>+                          border_color_offset,
>+                          enable_ewa);
> }
> 
> 
>diff --git a/src/mesa/drivers/dri/i965/brw_state.h b/src/mesa/drivers/dri/i965/brw_state.h
>index 71210b9..abf75ba 100644
>--- a/src/mesa/drivers/dri/i965/brw_state.h
>+++ b/src/mesa/drivers/dri/i965/brw_state.h
>@@ -267,7 +267,8 @@ void brw_emit_sampler_state(struct brw_context *brw,
>                             unsigned base_level,
>                             unsigned shadow_function,
>                             bool non_normalized_coordinates,
>-                            uint32_t border_color_offset);
>+                            uint32_t border_color_offset,
>+                            bool enable_ewa);
> 
> /* gen6_sf_state.c */
> void
>diff --git a/src/mesa/drivers/dri/i965/gen6_blorp.cpp b/src/mesa/drivers/dri/i965/gen6_blorp.cpp
>index e45705a..b60c187 100644
>--- a/src/mesa/drivers/dri/i965/gen6_blorp.cpp
>+++ b/src/mesa/drivers/dri/i965/gen6_blorp.cpp
>@@ -482,7 +482,8 @@ gen6_blorp_emit_sampler_state(struct brw_context *brw,
>                           0, /* base miplevel */
>                           0, /* shadow function */
>                           true, /* non-normalized coordinates */
>-                          0); /* border color offset - unused */
>+                          0, /* border color offset - unused */
>+                          false); /* enable EWA algorithm */
> 
>    return sampler_offset;
> }
>-- 
>1.9.1
>

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Attachments on bug 82463: 104434 | 104435 | 104436 | 104437 | 104438 | 104439 | 114245 | 114246 | 114248 | 114249

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