Several fixes for fp 16 rendering:

src/gpu/SkGpuDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGpuDevice.h"
 
 #include "GrBlurUtils.h"
@@ skipping 173 matching lines @@
         return nullptr;
     }
 
     if (!context) {
         return nullptr;
     }
 
     SkColorType ct = origInfo.colorType();
     SkAlphaType at = origInfo.alphaType();
     SkColorProfileType pt = origInfo.profileType();
-    if (kRGB_565_SkColorType == ct) {
+    if (kRGB_565_SkColorType == ct || kGray_8_SkColorType == ct) {
         at = kOpaque_SkAlphaType;  // force this setting
-    } else if (ct != kBGRA_8888_SkColorType && ct != kRGBA_8888_SkColorType) {
-        // Fall back from whatever ct was to default of kRGBA or kBGRA which is aliased as kN32
-        ct = kN32_SkColorType;
     }
     if (kOpaque_SkAlphaType != at) {
         at = kPremul_SkAlphaType;  // force this setting
     }
+
+    GrPixelConfig origConfig = SkImageInfo2GrPixelConfig(ct, at, pt, *context->caps());
+    if (!context->caps()->isConfigRenderable(origConfig, sampleCount > 0)) {
+        // Fall back from whatever ct was to default of kRGBA or kBGRA which is aliased as kN32
+        ct = kN32_SkColorType;
+    }
+
     const SkImageInfo info = SkImageInfo::Make(origInfo.width(), origInfo.height(), ct, at, pt);
 
     GrSurfaceDesc desc;
     desc.fFlags = kRenderTarget_GrSurfaceFlag;
     desc.fWidth = info.width();
     desc.fHeight = info.height();
     desc.fConfig = SkImageInfo2GrPixelConfig(info, *context->caps());
     desc.fSampleCnt = sampleCount;
     desc.fIsMipMapped = false;
     GrTexture* texture = context->textureProvider()->createTexture(desc, budgeted, nullptr, 0);
@@ skipping 1724 matching lines @@
 }
 
 SkImageFilter::Cache* SkGpuDevice::getImageFilterCache() {
     ASSERT_SINGLE_OWNER
     // We always return a transient cache, so it is freed after each
     // filter traversal.
     return SkGpuDevice::NewImageFilterCache();
 }
 
 #endif