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

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

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/ozone/platform/drm/gpu/client_native_pixmap_vgem.h"
+
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <vgem_drm.h>
+#include <xf86drm.h>
+
+#include "base/trace_event/trace_event.h"
+
+namespace ui {
+
+// static
+scoped_ptr<ClientNativePixmap> ClientNativePixmapVgem::ImportFromDmabuf(
+    int vgem_fd,
+    int dmabuf_fd,
+    const gfx::Size& size,
+    int stride) {
+  DCHECK_GE(vgem_fd, 0);
+  DCHECK_GE(dmabuf_fd, 0);
+  uint32_t vgem_bo_handle = 0;
+  int ret = drmPrimeFDToHandle(vgem_fd, dmabuf_fd, &vgem_bo_handle);
+  if (ret) {

[reveman, 2015/08/13 14:03:58]

can we DCHECK(!ret) instead?

[reveman, 2015/08/13 15:15:58]

ping?

[dshwang, 2015/08/13 15:45:28]

ah, I missed. Done.

BTW,Android and IOS return nullptr in the same situation. So now ozone behaves
slightly differently.
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/gpu...
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/gpu...

[reveman, 2015/08/13 17:16:43]

Yes, that's not ideal and we should change those implementations to fail hard
too. Not sure OOM is the only cause for those functions to fail though.

+    PLOG(ERROR) << "drmPrimeFDToHandle failed, handle:" << vgem_bo_handle;

[reveman, 2015/08/13 15:15:58]

btw, logging the vgem_bo_handle after failure seems weird. why would it not be 0
in that case?

[dshwang, 2015/08/13 15:45:28]

always 0. done.

+    return nullptr;
+  }
+  return make_scoped_ptr(
+      new ClientNativePixmapVgem(vgem_fd, vgem_bo_handle, size, stride));
+}
+
+ClientNativePixmapVgem::ClientNativePixmapVgem(int vgem_fd,
+                                               uint32_t vgem_bo_handle,
+                                               const gfx::Size& size,
+                                               int stride)
+    : vgem_fd_(vgem_fd),
+      vgem_bo_handle_(vgem_bo_handle),
+      size_(size),
+      stride_(stride),
+      data_(nullptr) {
+  DCHECK(vgem_bo_handle_);
+}
+
+ClientNativePixmapVgem::~ClientNativePixmapVgem() {
+  DCHECK(!data_);
+  struct drm_gem_close close = {0};
+  close.handle = vgem_bo_handle_;
+  int ret = drmIoctl(vgem_fd_, DRM_IOCTL_GEM_CLOSE, &close);
+  DCHECK(!ret) << "fail to free a vgem buffer.";
+}
+
+bool ClientNativePixmapVgem::Map(void** data) {
+  TRACE_EVENT0("gpu", "ClientNativePixmapVgem::Map");
+  DCHECK(!data_);
+  struct drm_mode_map_dumb mmap_arg = {0};
+  mmap_arg.handle = vgem_bo_handle_;
+
+  int ret = drmIoctl(vgem_fd_, DRM_IOCTL_VGEM_MODE_MAP_DUMB, &mmap_arg);
+  if (ret) {

[reveman, 2015/08/13 14:03:58]

What is the reason for this failing? I guess running out of virtual address
space, in which case we should call TerminateBecauseOutOfMemory.

[reveman, 2015/08/13 15:15:58]

ping?

[dshwang, 2015/08/13 15:45:28]

yes, mostly oom. I followed Android code. Now I added
TerminateBecauseOutOfMemory
https://code.google.com/p/chromium/codesearch#chromium/src/content/common/gpu...

+    PLOG(ERROR) << "fail to map a vgem buffer.";
+    return false;
+  }
+  DCHECK(mmap_arg.offset);
+
+  size_t size = stride_ * size_.height();
+  data_ = mmap(nullptr, size, (PROT_READ | PROT_WRITE), MAP_SHARED, vgem_fd_,
+               mmap_arg.offset);
+  DCHECK_NE(data_, MAP_FAILED);
+  *data = data_;
+  return true;
+}
+
+void ClientNativePixmapVgem::Unmap() {
+  TRACE_EVENT0("gpu", "ClientNativePixmapVgem::Unmap");
+  DCHECK(data_);
+
+  // TODO(dshwang): keep it consistently mapped, and unmap it in dtor.
+  size_t size = stride_ * size_.height();
+  int ret = munmap(data_, size);
+  DCHECK(!ret) << "fail to munmap a vgem buffer.";
+  data_ = nullptr;
+}
+
+void ClientNativePixmapVgem::GetStride(int* stride) const {
+  *stride = stride_;
+}
+
+}  // namespace ui