From 0e741e2dea688dce6f80a5c90fc0295938cd8eb6 Mon Sep 17 00:00:00 2001
From: Robert Phillips <robertphillips@google.com>
Date: Thu, 5 Aug 2021 15:34:15 -0400
Subject: [PATCH] Disable dithering on the PowerVR GE8320

FWIW, our PowerVRGE8320 reports that it has integer shader support.

Bug: b/195281495
Change-Id: Ie969d8e978404a5b8963bb5c71dedfa8945b2a2e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/436563
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
---
 src/gpu/GrCaps.cpp      |  2 ++
 src/gpu/GrCaps.h        |  5 +++++
 src/gpu/SkGr.cpp        | 10 +++++++---
 src/gpu/gl/GrGLCaps.cpp |  9 +++++++++
 4 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/src/gpu/GrCaps.cpp b/src/gpu/GrCaps.cpp
index 258e03818d..47368bd8a9 100644
--- a/src/gpu/GrCaps.cpp
+++ b/src/gpu/GrCaps.cpp
@@ -83,6 +83,7 @@ GrCaps::GrCaps(const GrContextOptions& options) {
     fRequiresManualFBBarrierAfterTessellatedStencilDraw = false;
     fNativeDrawIndexedIndirectIsBroken = false;
     fAvoidReorderingRenderTasks = false;
+    fAvoidDithering = false;
 
     fPreferVRAMUseOverFlushes = true;
 
@@ -250,6 +251,7 @@ void GrCaps::dumpJSON(SkJSONWriter* writer) const {
     writer->appendBool("Native draw indexed indirect is broken [workaround]",
                        fNativeDrawIndexedIndirectIsBroken);
     writer->appendBool("Avoid DAG reordering [workaround]", fAvoidReorderingRenderTasks);
+    writer->appendBool("Avoid Dithering [workaround]", fAvoidDithering);
 
     if (this->advancedBlendEquationSupport()) {
         writer->appendHexU32("Advanced Blend Equation Disable Flags", fAdvBlendEqDisableFlags);
diff --git a/src/gpu/GrCaps.h b/src/gpu/GrCaps.h
index f51d495588..8baa8258fc 100644
--- a/src/gpu/GrCaps.h
+++ b/src/gpu/GrCaps.h
@@ -493,6 +493,10 @@ public:
         return fAvoidReorderingRenderTasks;
     }
 
+    bool avoidDithering() const {
+        return fAvoidDithering;
+    }
+
     /**
      * Checks whether the passed color type is renderable. If so, the same color type is passed
      * back along with the default format used for the color type. If not, provides an alternative
@@ -565,6 +569,7 @@ protected:
     bool fRequiresManualFBBarrierAfterTessellatedStencilDraw : 1;
     bool fNativeDrawIndexedIndirectIsBroken          : 1;
     bool fAvoidReorderingRenderTasks                 : 1;
+    bool fAvoidDithering                             : 1;
 
     // ANGLE performance workaround
     bool fPreferVRAMUseOverFlushes                   : 1;
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 15bb31ade6..13b828d2a3 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -325,12 +325,16 @@ static inline float dither_range_for_config(GrColorType dstColorType) {
 }
 
 static std::unique_ptr<GrFragmentProcessor> make_dither_effect(
-        std::unique_ptr<GrFragmentProcessor> inputFP, float range, const GrShaderCaps* caps) {
+        std::unique_ptr<GrFragmentProcessor> inputFP, float range, const GrCaps* caps) {
     if (range == 0 || inputFP == nullptr) {
         return inputFP;
     }
 
-    if (caps->integerSupport()) {
+    if (caps->avoidDithering()) {
+        return inputFP;
+    }
+
+    if (caps->shaderCaps()->integerSupport()) {
         // This ordered-dither code is lifted from the cpu backend.
         static auto effect = SkMakeRuntimeEffect(SkRuntimeEffect::MakeForShader, R"(
             uniform half range;
@@ -500,7 +504,7 @@ static inline bool skpaint_to_grpaint_impl(GrRecordingContext* context,
     if (SkPaintPriv::ShouldDither(skPaint, GrColorTypeToSkColorType(ct)) && paintFP != nullptr) {
         float ditherRange = dither_range_for_config(ct);
         paintFP = make_dither_effect(
-                std::move(paintFP), ditherRange, context->priv().caps()->shaderCaps());
+                std::move(paintFP), ditherRange, context->priv().caps());
     }
 #endif
 
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 015e2f7562..b9e4560b7c 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -758,6 +758,15 @@ void GrGLCaps::init(const GrContextOptions& contextOptions,
         fShouldCollapseSrcOverToSrcWhenAble = true;
     }
 
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    if (ctxInfo.renderer() == GrGLRenderer::kPowerVRRogue) {
+        // https://b/195281495
+        // The TecnoSpark 3 Pro with a PowerVR GE8300 seems to have a steep dithering performance
+        // cliff in the Android Framework
+        fAvoidDithering = true;
+    }
+#endif
+
     FormatWorkarounds formatWorkarounds;
 
     if (!contextOptions.fDisableDriverCorrectnessWorkarounds) {