From 0ab7ab40c8765a2d10df510ce17d43a87eec8f06 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Ol=C5=A1=C3=A1k?= <marek.olsak@amd.com>
Date: Wed, 21 Oct 2020 12:34:51 -0400
Subject: [PATCH] radeonsi: tweak triangle list culling performance for GS fast
 launch

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7542>
---
 src/gallium/drivers/radeonsi/gfx10_shader_ngg.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c b/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c
index 9ccde8fe80b..1cad17195dd 100644
--- a/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c
+++ b/src/gallium/drivers/radeonsi/gfx10_shader_ngg.c
@@ -1941,7 +1941,10 @@ bool gfx10_ngg_calculate_subgroup_info(struct si_shader *shader)
    unsigned max_esverts_base = 128;
 
    if (shader->key.opt.ngg_culling & SI_NGG_CULL_GS_FAST_LAUNCH_TRI_LIST) {
-      max_gsprims_base = 128 / 3;
+      /* Exactly 1 wave32 executes culling in primitive threads (there is no
+       * divergence), other waves are idle.
+       */
+      max_gsprims_base = 32;
       max_esverts_base = max_gsprims_base * 3;
    } else if (shader->key.opt.ngg_culling & SI_NGG_CULL_GS_FAST_LAUNCH_TRI_STRIP) {
       max_gsprims_base = 126;