Reset all sampler units to ground state for GrContext

Skia uses multiple texture units, so we need to reset all
sampler units. This is a temporary workaround. We will create
GrContext for ES 3.0 soon, after SkiaRenderer + GL is shipped.

Bug: 1057271
Change-Id: I38fe243f86e91868226780960ddc997401ea3a1f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2150816
Commit-Queue: Peng Huang <penghuang@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Auto-Submit: Peng Huang <penghuang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759412}

gpu/command_buffer/service/context_state.cc

@@ -334,22 +334,15 @@ void ContextState::RestoreSamplerBinding(GLuint unit,
                                          const ContextState* prev_state) const {
   if (!feature_info_->IsES3Capable())
     return;
-  DCHECK(track_texture_and_sampler_units || unit == 0);
 
   GLuint cur_id = 0u;
-  if (track_texture_and_sampler_units) {
-    if (const auto& cur_sampler = sampler_units[unit])
-      cur_id = cur_sampler->service_id();
-  }
+  if (const auto& cur_sampler = sampler_units[unit])
+    cur_id = cur_sampler->service_id();
 
   base::Optional<GLuint> prev_id;
   if (prev_state) {
-    if (prev_state->track_texture_and_sampler_units) {
-      const auto& prev_sampler = prev_state->sampler_units[unit];
-      prev_id.emplace(prev_sampler ? prev_sampler->service_id() : 0);
-    } else if (prev_state->sampler_units_in_ground_state) {
-      prev_id.emplace(0);
-    }
+    const auto& prev_sampler = prev_state->sampler_units[unit];
+    prev_id.emplace(prev_sampler ? prev_sampler->service_id() : 0);
   }
 
   if (!prev_id || cur_id != *prev_id)
@@ -459,8 +452,6 @@ void ContextState::RestoreAllTextureUnitAndSamplerBindings(
       if (!prev_state->track_texture_and_sampler_units) {
         texture_units_in_ground_state =
             prev_state->texture_units_in_ground_state;
-        sampler_units_in_ground_state =
-            prev_state->sampler_units_in_ground_state;
         return;
       }
 
@@ -471,22 +462,22 @@ void ContextState::RestoreAllTextureUnitAndSamplerBindings(
           break;
         }
       }
-      sampler_units_in_ground_state = true;
-      for (size_t i = 1; i < prev_state->sampler_units.size(); ++i) {
-        const auto& sampler = prev_state->sampler_units[i];
-        if (sampler && sampler->service_id() != 0) {
-          sampler_units_in_ground_state = false;
-          break;
-        }
-      }
+
+      // Make sure all texture units are in ground state, we need to reset the
+      // 0th texture units. If some of non zero textures aren't in ground state,
+      // when another context is being make current, we will restore all texture
+      // units, then it is not necessary to reset the 0th texture units anymore.
+      if (texture_units_in_ground_state)
+        RestoreTextureUnitBindings(0, prev_state);
     } else {
       texture_units_in_ground_state = false;
-      sampler_units_in_ground_state = false;
     }
-    // Even if |track_texture_and_sampler_units| is false, we still need to
-    // reset texture unit 0 and sampler unit 0 to ground state.
-    RestoreTextureUnitBindings(0, prev_state);
-    RestoreSamplerBinding(0, prev_state);
+
+    // GrContext is not aware of sampler objects and skia will not restore them,
+    // so we need to reset them to ground state.
+    // TODO(penghuang): Remove it when GrContext is created for ES 3.0.
+    for (size_t i = 0; i < sampler_units.size(); ++i)
+      RestoreSamplerBinding(i, prev_state);
   } else {
     // Restore Texture state.
     for (size_t i = 0; i < texture_units.size(); ++i) {

gpu/command_buffer/service/context_state.h

@@ -364,7 +364,6 @@ struct GPU_GLES2_EXPORT ContextState {
 
   // Which samplers are bound to each texture unit;
   std::vector<scoped_refptr<Sampler>> sampler_units;
-  mutable bool sampler_units_in_ground_state = true;
 
   // We create a transform feedback as the default one per ES3 enabled context
   // instead of using GL's default one to make context switching easier.

gpu/command_buffer/service/raster_decoder_unittest_base.cc

@@ -172,6 +172,9 @@ void RasterDecoderTestBase::InitDecoder(const InitState& init) {
   EXPECT_CALL(*gl_, GetIntegerv(GL_MAX_VERTEX_ATTRIBS, _))
       .WillOnce(SetArgPointee<1>(8u))
       .RetiresOnSaturation();
+  EXPECT_CALL(*gl_, GetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, _))
+      .WillOnce(SetArgPointee<1>(8u))
+      .RetiresOnSaturation();
   ContextStateTestHelpers::SetupInitState(gl_.get(), feature_info(),
                                           gfx::Size(1, 1));
 

gpu/command_buffer/service/shared_context_state.cc

@@ -279,6 +279,18 @@ bool SharedContextState::InitializeGL(
     return false;
   }
 
+  const GLint kGLES2RequiredMinimumTextureUnits = 8u;
+  GLint max_texture_units = 0;
+  api->glGetIntegervFn(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &max_texture_units);
+  if (max_texture_units < kGLES2RequiredMinimumTextureUnits) {
+    LOG(ERROR)
+        << "SharedContextState::InitializeGL failure max_texture_units : "
+        << max_texture_units << " is less that minimum required : "
+        << kGLES2RequiredMinimumTextureUnits;
+    feature_info_ = nullptr;
+    return false;
+  }
+
   context_state_ = std::make_unique<gles2::ContextState>(
       feature_info_.get(), false /* track_texture_and_sampler_units */);
 
@@ -291,6 +303,11 @@ bool SharedContextState::InitializeGL(
   context_state_->InitCapabilities(nullptr);
   context_state_->InitState(nullptr);
 
+  // Init |sampler_units|, ContextState uses the size of it to reset sampler to
+  // ground state.
+  // TODO(penghuang): remove it when GrContext is created with ES 3.0.
+  context_state_->sampler_units.resize(max_texture_units);
+
   GLenum driver_status = real_context_->CheckStickyGraphicsResetStatus();
   if (driver_status != GL_NO_ERROR) {
     // If the context was lost at any point before or during initialization,

gpu/command_buffer/service/shared_context_state_unittest.cc

@@ -74,6 +74,9 @@ TEST_F(SharedContextStateTest, InitFailsIfLostContext) {
   EXPECT_CALL(gl_interface, GetIntegerv(GL_MAX_VERTEX_ATTRIBS, _))
       .WillOnce(SetArgPointee<1>(8u))
       .RetiresOnSaturation();
+  EXPECT_CALL(gl_interface, GetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, _))
+      .WillOnce(SetArgPointee<1>(8u))
+      .RetiresOnSaturation();
   ContextStateTestHelpers::SetupInitState(&gl_interface, feature_info.get(),
                                           gfx::Size(1, 1));