gpu: Disallow use of IOSurfaces for half-float format with swiftshader.

R=kbr@chromium.org

Bug: 998038
Change-Id: Ic31d28938ef205b36657fc7bd297fe8a63d08543
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1798052
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Auto-Submit: Khushal <khushalsagar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#695826}

gpu/command_buffer/service/feature_info.cc

@@ -426,6 +426,11 @@ void FeatureInfo::EnableOESTextureHalfFloatLinear() {
     return;
   AddExtensionString("GL_OES_texture_half_float_linear");
   feature_flags_.enable_texture_half_float_linear = true;
+
+  // TODO(capn) : Re-enable this once we have ANGLE+SwiftShader supporting
+  // IOSurfaces.
+  if (workarounds_.disable_half_float_for_gmb)
+    return;
   feature_flags_.gpu_memory_buffer_formats.Add(gfx::BufferFormat::RGBA_F16);
 }
 

gpu/config/gpu_driver_bug_list.json

@@ -3345,6 +3345,18 @@
       "features": [
         "exit_on_context_lost"
       ]
+    },
+    {
+      "id": 311,
+      "cr_bugs": [998038],
+      "description": "Don't use IOSurface backed GMBs for half float textures with swiftshader",
+      "os": {
+        "type" : "macosx"
+      },
+      "gl_renderer": "Google SwiftShader*",
+      "features": [
+          "disable_half_float_for_gmb"
+      ]
     }
   ]
 }

gpu/config/gpu_workaround_list.txt

@@ -114,3 +114,4 @@ wake_up_gpu_before_drawing
 use_copyteximage2d_instead_of_readpixels_on_multisampled_textures
 use_eqaa_storage_samples_2
 max_3d_array_texture_size_1024
+disable_half_float_for_gmb