ozone: Implement zero/one-copy texture for Ozone GBM.

ui/ozone/platform/drm/gpu/gbm_buffer.cc

Index: ui/ozone/platform/drm/gpu/gbm_buffer.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer.cc b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
index 362f77c8dd6566ca08c6b26fea9341c950f3e8ff..77e05a80f3dd477f379fc4c9aea7a03fa9741b5f 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
@@ -10,7 +10,9 @@
 #include <xf86drm.h>
 
 #include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
 #include "base/trace_event/trace_event.h"
+#include "ui/gfx/gpu_memory_buffer.h"
 #include "ui/ozone/platform/drm/gpu/gbm_device.h"
 
 namespace ui {
@@ -29,6 +31,23 @@ int GetGbmFormatFromBufferFormat(SurfaceFactoryOzone::BufferFormat fmt) {
   }
 }
 
+bool ShareToRenderProcess(int fd, base::FileDescriptor* new_handle) {
+  int duped_handle = HANDLE_EINTR(dup(fd));
+  if (duped_handle < 0) {
+    DPLOG(ERROR) << "dup() failed.";
+    *new_handle = base::FileDescriptor();
+    return false;
+  }
+
+  *new_handle = base::FileDescriptor(duped_handle, true);
+  return true;
+}
+
+unsigned long StrideInBytes(int width) {
+  // Both BGRA_8888 and RGBX_8888 has 4 byte per pixel.
+  return width * 4;
+}
+
 }  // namespace
 
 GbmBuffer::GbmBuffer(const scoped_refptr<GbmDevice>& gbm,
@@ -51,8 +70,9 @@ scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
   TRACE_EVENT2("drm", "GbmBuffer::CreateBuffer", "device",
                gbm->device_path().value(), "size", size.ToString());
   unsigned flags = GBM_BO_USE_RENDERING;
-  if (scanout)
-    flags |= GBM_BO_USE_SCANOUT;
+  // SCANOUT allocates continuous memory, so better for performance even if
+  // |scanout| is false.
+  flags |= GBM_BO_USE_SCANOUT;
   gbm_bo* bo = gbm_bo_create(gbm->device(), size.width(), size.height(),
                              GetGbmFormatFromBufferFormat(format), flags);
   if (!bo)
@@ -86,6 +106,34 @@ GbmPixmap::~GbmPixmap() {
     close(dma_buf_);
 }
 
+bool GbmPixmap::ExportDmaBuf(int vgem_fd, gfx::GpuMemoryBufferHandle* handle) {
+  DCHECK(StrideInBytes(buffer_->GetSize().width()) ==
+         gbm_bo_get_stride(buffer_->bo()));
+
+  base::FileDescriptor dup_handle;
+  if (!ShareToRenderProcess(dma_buf_, &dup_handle)) {
+    DLOG(ERROR) << "Fail to duplicate a DMA-BUF file descriptor";
+    return false;
+  }
+
+  if (vgem_fd < 0) {
+    LOG(ERROR) << "This device doesn't support vGEM.";
+    return false;
+  }
+
+  base::FileDescriptor dup_device_handle;
+  if (!ShareToRenderProcess(vgem_fd, &dup_device_handle)) {
+    base::ScopedFD fd(dup_handle.fd);
+    DLOG(ERROR) << "Fail to duplicate a DRM file descriptor";
+    return false;
+  }
+
+  handle->handle = dup_handle;
+  // TODO(dshwang): pass |device_handle| only one time for each render process.
+  handle->device_handle = dup_device_handle;
+  return true;
+}
+
 void* GbmPixmap::GetEGLClientBuffer() {
   return nullptr;
 }
@@ -98,4 +146,8 @@ int GbmPixmap::GetDmaBufPitch() {
   return gbm_bo_get_stride(buffer_->bo());
 }
 
+NativePixmap::BufferUsage GbmPixmap::GetBufferUsage() const {
+  return buffer_->GetFramebufferId() ? SCANOUT : MAP;
+}
+
 }  // namespace ui