drm_hwcomposer: Add composition skipping backend

This display backend may be chosen by setting the hwc.backend_override
system property to the "client" value.

Suggested-by: Andrii Chepurnyi <andrii_chepurnyi@epam.com>
Signed-off-by: Matvii Zorin <matvii.zorin@globallogic.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/backend/backendclient.cpp b/backend/backendclient.cpp
new file mode 100644
index 0000000..3f3cd44
--- /dev/null
+++ b/backend/backendclient.cpp
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "backendclient.h"
+#include "backendmanager.h"
+#include "drmhwctwo.h"
+
+namespace android {
+
+HWC2::Error BackendClient::ValidateDisplay(DrmHwcTwo::HwcDisplay *display,
+                                           uint32_t *num_types,
+                                           uint32_t * /*num_requests*/) {
+  for (auto & [ layer_handle, layer ] : display->layers()) {
+    layer.set_validated_type(HWC2::Composition::Client);
+    ++*num_types;
+  }
+  return HWC2::Error::HasChanges;
+}
+
+REGISTER_BACKEND("client", BackendClient);
+
+}  // namespace android