ui: Rename gfx::BufferUsage enum values and add BufferUsage::GPU_READ.

The problem with the current usage modes is that we currently use
SCANOUT for anything that doesn't require CPU access. When importing
a buffer we typically don't care about anything but having the GPU
be able to read from it. SCANOUT is not a good description of that
and currently means GPU read/write support.

This patch attempts to make usage more explicit and it solves the
use case where a buffer type can only provide GPU read and not GPU
write support (e.g. SHM fallback). Here are the new usage modes:

- GPU_READ
- GPU_READ_WRITE
- GPU_READ_CPU_READ_WRITE

GPU_READ is useful when importing a buffer and all you care about is
being able to use it for sampling and optionally scanout.

GPU_READ_WRITE is useful for things like WebGL or GPU raster where
we want the ability to write to the buffer using GL and potentially
use it for scanout.

GPU_READ_CPU_READ_WRITE is the usage mode that allows CPU access and
is used for one-copy and zero-copy texture initialization. There's
nothing preventing this mode from also supporting scanout.

- GPU_READ_CPU_READ_WRITE_PERSISTENT

This usage mode indicates that the data will be persistent across
Unmap()/Map() calls but will likely become part of the normal
GPU_READ_CPU_READ_WRITE usage once all buffer types support this.

BUG=538325
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1420923005

Cr-Commit-Position: refs/heads/master@{#356108}

10 files changed, 52 insertions, 45 deletions

diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index ed80f62..e278394 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -144,10 +144,12 @@ Compositor::Compositor(ui::ContextFactory* context_factory,
   // doesn't currently support partial raster.
   settings.use_partial_raster = !settings.use_zero_copy;
 
-  // Use PERSISTENT_MAP memory buffers to support partial tile raster if needed.
-  gfx::BufferUsage usage = settings.use_partial_raster
-                               ? gfx::BufferUsage::PERSISTENT_MAP
-                               : gfx::BufferUsage::MAP;
+  // Use CPU_READ_WRITE_PERSISTENT memory buffers to support partial tile
+  // raster if needed.
+  gfx::BufferUsage usage =
+      settings.use_partial_raster
+          ? gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT
+          : gfx::BufferUsage::GPU_READ_CPU_READ_WRITE;
 
   for (size_t format = 0;
       format < static_cast<size_t>(gfx::BufferFormat::LAST) + 1; format++) {
diff --git a/ui/gfx/buffer_types.h b/ui/gfx/buffer_types.h
index aabfb41..2c87905 100644
--- a/ui/gfx/buffer_types.h
+++ b/ui/gfx/buffer_types.h
@@ -29,11 +29,20 @@ enum class BufferFormat {
 };
 
 // The usage mode affects how a buffer can be used. Only buffers created with
-// MAP can be mapped into the client's address space and accessed by the CPU.
-// PERSISTENT_MAP adds the additional condition that successive Map() calls
-// (with Unmap() calls between) will return a pointer to the same memory
-// contents.
-enum class BufferUsage { MAP, PERSISTENT_MAP, SCANOUT, LAST = SCANOUT };
+// *_CPU_READ_WRITE_* can be mapped into the client's address space and accessed
+// by the CPU. *_CPU_READ_WRITE_PERSISTENT adds the additional condition that
+// successive Map() calls (with Unmap() calls between) will return a pointer to
+// the same memory contents.
+enum class BufferUsage {
+  GPU_READ,
+  GPU_READ_WRITE,
+  GPU_READ_CPU_READ_WRITE,
+  // TODO(reveman): Merge this with GPU_READ_CPU_READ_WRITE when SurfaceTexture
+  // backed buffers are single buffered and support it.
+  GPU_READ_CPU_READ_WRITE_PERSISTENT,
+
+  LAST = GPU_READ_CPU_READ_WRITE_PERSISTENT
+};
 
 }  // namespace gfx
 
diff --git a/ui/gl/gl_bindings.h b/ui/gl/gl_bindings.h
index c1ad779..f043bef 100644
--- a/ui/gl/gl_bindings.h
+++ b/ui/gl/gl_bindings.h
@@ -127,8 +127,7 @@
 #define GL_COMMANDS_COMPLETED_CHROMIUM                   0x84F7
 
 // GL_CHROMIUM_gpu_memory_buffer_image
-#define GL_MAP_CHROMIUM                                  0x78F1
-#define GL_SCANOUT_CHROMIUM                              0x78F2
+#define GL_READ_WRITE_CHROMIUM                           0x78F2
 
 // GL_CHROMIUM_yuv_420_image
 #define GL_RGB_YUV_420_CHROMIUM                          0x78FA
diff --git a/ui/gl/gl_enums_implementation_autogen.h b/ui/gl/gl_enums_implementation_autogen.h
index 54dea5a..e6d7c36 100644
--- a/ui/gl/gl_enums_implementation_autogen.h
+++ b/ui/gl/gl_enums_implementation_autogen.h
@@ -46,9 +46,6 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x0BC2, "GL_ALPHA_TEST_REF_QCOM",
     },
     {
-        0x78EF, "GL_PIXEL_UNPACK_TRANSFER_BUFFER_BINDING_CHROMIUM",
-    },
-    {
         0x884D, "GL_TEXTURE_COMPARE_FUNC_EXT",
     },
     {
@@ -97,7 +94,7 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x9500, "GL_PERFQUERY_GPA_EXTENDED_COUNTERS_INTEL",
     },
     {
-        0x78F2, "GL_SCANOUT_CHROMIUM",
+        0x78F2, "GL_READ_WRITE_CHROMIUM",
     },
     {
         0x9138, "GL_COMPRESSED_RGBA_PVRTC_4BPPV2_IMG",
@@ -1165,9 +1162,6 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x8A44, "GL_UNIFORM_BLOCK_REFERENCED_BY_VERTEX_SHADER",
     },
     {
-        0x6000, "GL_TEXTURE_POOL_CHROMIUM",
-    },
-    {
         0x0B74, "GL_DEPTH_FUNC",
     },
     {
@@ -1495,7 +1489,7 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x04, "GL_LINE_TO_CHROMIUM",
     },
     {
-        0x0BA7, "GL_PATH_PROJECTION_MATRIX_CHROMIUM",
+        0x8905, "GL_MAX_PROGRAM_TEXEL_OFFSET",
     },
     {
         0x00080000, "GL_STENCIL_BUFFER_BIT3_QCOM",
@@ -1906,6 +1900,9 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x8CD9, "GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS",
     },
     {
+        24, "GL_SYNC_TOKEN_SIZE_CHROMIUM",
+    },
+    {
         0x84CC, "GL_TEXTURE12",
     },
     {
@@ -1915,7 +1912,7 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x84CA, "GL_TEXTURE10",
     },
     {
-        0x78F1, "GL_MAP_CHROMIUM",
+        0x0BA7, "GL_PATH_PROJECTION_MATRIX_CHROMIUM",
     },
     {
         0x84CF, "GL_TEXTURE15",
@@ -2269,9 +2266,6 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x84DC, "GL_TEXTURE28",
     },
     {
-        0x6002, "GL_TEXTURE_POOL_UNMANAGED_CHROMIUM",
-    },
-    {
         0x84DA, "GL_TEXTURE26",
     },
     {
@@ -2845,7 +2839,7 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x78EE, "GL_PIXEL_PACK_TRANSFER_BUFFER_BINDING_CHROMIUM",
     },
     {
-        0x6001, "GL_TEXTURE_POOL_MANAGED_CHROMIUM",
+        0x78EF, "GL_PIXEL_UNPACK_TRANSFER_BUFFER_BINDING_CHROMIUM",
     },
     {
         0x0B45, "GL_CULL_FACE_MODE",
@@ -2857,9 +2851,6 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x00100000, "GL_STENCIL_BUFFER_BIT4_QCOM",
     },
     {
-        24, "GL_SYNC_TOKEN_SIZE_CHROMIUM",
-    },
-    {
         0x8E4E, "GL_LAST_VERTEX_CONVENTION_EXT",
     },
     {
@@ -3001,9 +2992,6 @@ static const GLEnums::EnumToString enum_to_string_table[] = {
         0x0A, "GL_QUADRATIC_CURVE_TO_CHROMIUM",
     },
     {
-        0x8905, "GL_MAX_PROGRAM_TEXEL_OFFSET",
-    },
-    {
         0x8508, "GL_DECR_WRAP",
     },
     {
diff --git a/ui/gl/gl_surface_ozone.cc b/ui/gl/gl_surface_ozone.cc
index ad264cc..377597d 100644
--- a/ui/gl/gl_surface_ozone.cc
+++ b/ui/gl/gl_surface_ozone.cc
@@ -565,7 +565,7 @@ bool GLSurfaceOzoneSurfacelessSurfaceImpl::CreatePixmaps() {
             ->GetSurfaceFactoryOzone()
             ->CreateNativePixmap(widget_, GetSize(),
                                  gfx::BufferFormat::BGRA_8888,
-                                 gfx::BufferUsage::SCANOUT);
+                                 gfx::BufferUsage::GPU_READ_WRITE);
     if (!pixmap)
       return false;
     scoped_refptr<GLImageOzoneNativePixmap> image =
diff --git a/ui/ozone/demo/surfaceless_gl_renderer.cc b/ui/ozone/demo/surfaceless_gl_renderer.cc
index 60575d6..4b3d555 100644
--- a/ui/ozone/demo/surfaceless_gl_renderer.cc
+++ b/ui/ozone/demo/surfaceless_gl_renderer.cc
@@ -40,7 +40,7 @@ bool SurfacelessGlRenderer::BufferWrapper::Initialize(
       OzonePlatform::GetInstance()
           ->GetSurfaceFactoryOzone()
           ->CreateNativePixmap(widget, size, gfx::BufferFormat::BGRX_8888,
-                               gfx::BufferUsage::SCANOUT);
+                               gfx::BufferUsage::GPU_READ_WRITE);
   scoped_refptr<gfx::GLImageOzoneNativePixmap> image(
       new gfx::GLImageOzoneNativePixmap(size, GL_RGB));
   if (!image->Initialize(pixmap.get(), gfx::BufferFormat::BGRX_8888)) {
diff --git a/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc b/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc
index ec832cb..d8c701c 100644
--- a/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc
+++ b/ui/ozone/platform/drm/client_native_pixmap_factory_gbm.cc
@@ -47,12 +47,13 @@ class ClientNativePixmapFactoryGbm : public ClientNativePixmapFactory {
   bool IsConfigurationSupported(gfx::BufferFormat format,
                                 gfx::BufferUsage usage) const override {
     switch (usage) {
-      case gfx::BufferUsage::SCANOUT:
+      case gfx::BufferUsage::GPU_READ:
+      case gfx::BufferUsage::GPU_READ_WRITE:
         return format == gfx::BufferFormat::RGBA_8888 ||
                format == gfx::BufferFormat::BGRA_8888 ||
                format == gfx::BufferFormat::BGRX_8888;
-      case gfx::BufferUsage::MAP:
-      case gfx::BufferUsage::PERSISTENT_MAP: {
+      case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE:
+      case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT: {
 #if defined(USE_VGEM_MAP)
         return vgem_fd_.is_valid() && format == gfx::BufferFormat::BGRA_8888;
 #else
@@ -70,8 +71,8 @@ class ClientNativePixmapFactoryGbm : public ClientNativePixmapFactory {
     base::ScopedFD scoped_fd(handle.fd.fd);
 
     switch (usage) {
-      case gfx::BufferUsage::MAP:
-      case gfx::BufferUsage::PERSISTENT_MAP:
+      case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE:
+      case gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT:
 #if defined(USE_VGEM_MAP)
         // A valid |vgem_fd_| is required to acquire a VGEM bo. |vgem_fd_| is
         // set before a widget is created.
@@ -81,7 +82,8 @@ class ClientNativePixmapFactoryGbm : public ClientNativePixmapFactory {
 #endif
         NOTREACHED();
         return nullptr;
-      case gfx::BufferUsage::SCANOUT:
+      case gfx::BufferUsage::GPU_READ:
+      case gfx::BufferUsage::GPU_READ_WRITE:
         return make_scoped_ptr<ClientNativePixmapGbm>(
             new ClientNativePixmapGbm);
     }
diff --git a/ui/ozone/platform/drm/gpu/drm_thread.cc b/ui/ozone/platform/drm/gpu/drm_thread.cc
index 901dedb..19ecdfb 100644
--- a/ui/ozone/platform/drm/gpu/drm_thread.cc
+++ b/ui/ozone/platform/drm/gpu/drm_thread.cc
@@ -34,7 +34,7 @@ class GbmBufferGenerator : public ScanoutBufferGenerator {
                                       const gfx::Size& size) override {
     scoped_refptr<GbmDevice> gbm(static_cast<GbmDevice*>(drm.get()));
     return GbmBuffer::CreateBuffer(gbm, format, size,
-                                   gfx::BufferUsage::SCANOUT);
+                                   gfx::BufferUsage::GPU_READ_WRITE);
   }
 
  protected:
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer.cc b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
index 8c3c396..b94164d 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
@@ -25,7 +25,10 @@ namespace ui {
 GbmBuffer::GbmBuffer(const scoped_refptr<GbmDevice>& gbm,
                      gbm_bo* bo,
                      gfx::BufferUsage usage)
-    : GbmBufferBase(gbm, bo, usage == gfx::BufferUsage::SCANOUT),
+    : GbmBufferBase(gbm,
+                    bo,
+                    usage == gfx::BufferUsage::GPU_READ ||
+                        usage == gfx::BufferUsage::GPU_READ_WRITE),
       usage_(usage) {}
 
 GbmBuffer::~GbmBuffer() {
@@ -41,10 +44,12 @@ scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
     gfx::BufferUsage usage) {
   TRACE_EVENT2("drm", "GbmBuffer::CreateBuffer", "device",
                gbm->device_path().value(), "size", size.ToString());
-  bool use_scanout = (usage == gfx::BufferUsage::SCANOUT);
+  bool with_cpu_access =
+      usage == gfx::BufferUsage::GPU_READ_CPU_READ_WRITE ||
+      usage == gfx::BufferUsage::GPU_READ_CPU_READ_WRITE_PERSISTENT;
   unsigned flags = 0;
   // GBM_BO_USE_SCANOUT is the hint of x-tiling.
-  if (use_scanout)
+  if (!with_cpu_access)
     flags = GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING;
   gbm_bo* bo = gbm_bo_create(gbm->device(), size.width(), size.height(),
                              GetFourCCFormatFromBufferFormat(format), flags);
@@ -52,7 +57,7 @@ scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
     return nullptr;
 
   scoped_refptr<GbmBuffer> buffer(new GbmBuffer(gbm, bo, usage));
-  if (use_scanout && !buffer->GetFramebufferId())
+  if (!with_cpu_access && !buffer->GetFramebufferId())
     return nullptr;
 
   return buffer;
@@ -140,7 +145,8 @@ bool GbmPixmap::ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
     return false;
   }
 
-  DCHECK(buffer_->GetUsage() == gfx::BufferUsage::SCANOUT);
+  DCHECK(buffer_->GetUsage() == gfx::BufferUsage::GPU_READ ||
+         buffer_->GetUsage() == gfx::BufferUsage::GPU_READ_WRITE);
   surface_manager_->GetSurface(widget)->QueueOverlayPlane(OverlayPlane(
       buffer_, plane_z_order, plane_transform, display_bounds, crop_rect));
   return true;
diff --git a/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc b/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
index 42be306..f140f82 100644
--- a/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_surface_factory.cc
@@ -110,7 +110,8 @@ scoped_refptr<ui::NativePixmap> GbmSurfaceFactory::CreateNativePixmap(
 #if !defined(OS_CHROMEOS)
   // Support for memory mapping accelerated buffers requires some
   // CrOS-specific patches (using vgem).
-  DCHECK(gfx::BufferUsage::SCANOUT == usage);
+  DCHECK(gfx::BufferUsage::GPU_READ == usage ||
+         gfx::BufferUsage::GPU_READ_WRITE == usage);
 #endif
 
   scoped_refptr<GbmBuffer> buffer =