Attachment 136820 Details for Bug 104487 – Patch that should fix the hang

[patch] Patch that should fix the hang

0001-i965-Bind-null-render-targets-for-shadow-sampling-co.patch (text/plain), 3.27 KB, created by Kenneth Graunke on 2018-01-17 23:47:47 UTC

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Creator: Kenneth Graunke

Created: 2018-01-17 23:47:47 UTC

Size: 3.27 KB

patch

obsolete

>From 0ff1bfbad3ec7444b6240d3cc6375b1a58436c65 Mon Sep 17 00:00:00 2001
>From: Kenneth Graunke <kenneth@whitecape.org>
>Date: Wed, 17 Jan 2018 14:16:04 -0800
>Subject: [PATCH] i965: Bind null render targets for shadow sampling + color.
>
>Portal 2 appears to bind RGBA8888_UNORM textures to a sampler2DShadow,
>and calls shadow2D() on it.  This causes undefined behavior in OpenGL.
>
>Unfortunately, our sampler appears to hang in this scenario, which is
>not acceptable.  Just give them a null surface instead, which returns
>all zeroes.
>
>Fixes GPU hangs in Portal 2 on Kabylake.
>
>Huge thanks to Jason Ekstrand for noticing this crazy behavior while
>sifting through crash dumps.
>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104487
>---
> src/mesa/drivers/dri/i965/brw_wm_surface_state.c | 33 +++++++++++++++++++++++-
> 1 file changed, 32 insertions(+), 1 deletion(-)
>
>diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
>index adf60a840b0..38af6bc0dea 100644
>--- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
>+++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
>@@ -1095,6 +1095,14 @@ const struct brw_tracked_state brw_renderbuffer_read_surfaces = {
>    .emit = update_renderbuffer_read_surfaces,
> };
> 
>+static bool
>+is_depth_texture(struct intel_texture_object *iobj)
>+{
>+   GLenum base_format = _mesa_get_format_base_format(iobj->_Format);
>+   return base_format == GL_DEPTH_COMPONENT ||
>+          (base_format == GL_DEPTH_STENCIL && !iobj->base.StencilSampling);
>+}
>+
> static void
> update_stage_texture_surfaces(struct brw_context *brw,
>                               const struct gl_program *prog,
>@@ -1121,9 +1129,32 @@ update_stage_texture_surfaces(struct brw_context *brw,
>       if (prog->SamplersUsed & (1 << s)) {
>          const unsigned unit = prog->SamplerUnits[s];
>          const bool used_by_txf = prog->info.textures_used_by_txf & (1 << s);
>+         struct gl_texture_object *obj = ctx->Texture.Unit[unit]._Current;
>+         struct intel_texture_object *iobj = intel_texture_object(obj);
> 
>          /* _NEW_TEXTURE */
>-         if (ctx->Texture.Unit[unit]._Current) {
>+         if (!obj)
>+            continue;
>+
>+         if ((prog->ShadowSamplers & (1 << s)) && !is_depth_texture(iobj)) {
>+            /* A programming note for the sample_c message says:
>+             *
>+             *    "The Surface Format of the associated surface must be
>+             *     indicated as supporting shadow mapping as indicated in the
>+             *     surface format table."
>+             *
>+             * Accessing non-depth textures via a sampler*Shadow type is
>+             * undefined.  GLSL 4.50 page 162 says:
>+             *
>+             *    "If a shadow texture call is made to a sampler that does not
>+             *     represent a depth texture, then results are undefined."
>+             *
>+             * We give them a null surface (zeros) for undefined.  We've seen
>+             * GPU hangs with color buffers and sample_c, so we try and avoid
>+             * those with this hack.
>+             */
>+            emit_null_surface_state(brw, NULL, surf_offset + s);
>+         } else {
>             brw_update_texture_surface(ctx, unit, surf_offset + s, for_gather,
>                                        used_by_txf, plane);
>          }
>-- 
>2.15.1
>

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