Fix BufferHubBuffer black screen

1/ BufferHubService should read back fields of
HardwareBufferDescription of allocated BufferNode and send them back
to the client.
2/ Update some minor naming for better readability.

Bug: 122959735
Test: cts-tradefed run commandAndExit cts -m CtsNativeHardwareTestCases
Change-Id: I10a176810d78c754fe0b69d4128078fc17d50035

2 files changed, 11 insertions, 5 deletions

diff --git a/libs/ui/BufferHubBuffer.cpp b/libs/ui/BufferHubBuffer.cpp
index 405bcb62e1..604665bc91 100644
--- a/libs/ui/BufferHubBuffer.cpp
+++ b/libs/ui/BufferHubBuffer.cpp
@@ -79,10 +79,10 @@ BufferHubBuffer::BufferHubBuffer(uint32_t width, uint32_t height, uint32_t layer
     sp<IBufferClient> client;
     BufferTraits bufferTraits;
     IBufferHub::allocateBuffer_cb alloc_cb = [&](const auto& status, const auto& outClient,
-                                                 const auto& traits) {
+                                                 const auto& outTraits) {
         ret = status;
         client = std::move(outClient);
-        bufferTraits = std::move(traits);
+        bufferTraits = std::move(outTraits);
     };
 
     if (!bufferhub->allocateBuffer(desc, static_cast<uint32_t>(userMetadataSize), alloc_cb)
@@ -116,10 +116,10 @@ BufferHubBuffer::BufferHubBuffer(const sp<NativeHandle>& token) {
     sp<IBufferClient> client;
     BufferTraits bufferTraits;
     IBufferHub::importBuffer_cb import_cb = [&](const auto& status, const auto& outClient,
-                                                const auto& traits) {
+                                                const auto& outTraits) {
         ret = status;
         client = std::move(outClient);
-        bufferTraits = std::move(traits);
+        bufferTraits = std::move(outTraits);
     };
 
     // hidl_handle(native_handle_t*) simply creates a raw pointer reference withouth ownership
diff --git a/services/bufferhub/BufferHubService.cpp b/services/bufferhub/BufferHubService.cpp
index 90ac1c2535..ade08e7d17 100644
--- a/services/bufferhub/BufferHubService.cpp
+++ b/services/bufferhub/BufferHubService.cpp
@@ -73,7 +73,13 @@ Return<void> BufferHubService::allocateBuffer(const HardwareBufferDescription& d
             buildBufferInfo(bufferInfoStorage, node->id(), node->addNewActiveClientsBitToMask(),
                             node->userMetadataSize(), node->metadata().ashmemFd(),
                             node->eventFd().get());
-    BufferTraits bufferTraits = {/*bufferDesc=*/description,
+    // During the gralloc allocation carried out by BufferNode, gralloc allocator will populate the
+    // fields of its HardwareBufferDescription (i.e. strides) according to the actual
+    // gralloc implementation. We need to read those fields back and send them to the client via
+    // BufferTraits.
+    HardwareBufferDescription allocatedBufferDesc;
+    memcpy(&allocatedBufferDesc, &node->bufferDesc(), sizeof(AHardwareBuffer_Desc));
+    BufferTraits bufferTraits = {/*bufferDesc=*/allocatedBufferDesc,
                                  /*bufferHandle=*/hidl_handle(node->bufferHandle()),
                                  /*bufferInfo=*/std::move(bufferInfo)};