commit 63a699e14e0945015d978be16fbd5703d0b370e9
author Drew Davenport <ddavenport@google.com> Fri Dec 13 15:00:00 2024 -0700
committer Drew Davenport <ddavenport@google.com> Mon Dec 16 17:53:16 2024 -0700
tree 47e9348f7bc65eada0efc76b050b001d178d3a23
parent 33121b799af86e837114c524428ff9ac89a0f7bc

drm_hwcomposer: Set vsync callback on demand

Set and clear a vsync callback based on when the client requests vsync
events to be enabled or not. The new vsync callback does not need to
acquire the global resource lock.

The vsync callback uses the vsync period that was set in the VSyncWorker
rather than querying it from the HwcDisplay.

Change-Id: Ic7868af4963ad40aa5a0982a190c67f1642d5b32
Signed-off-by: Drew Davenport <ddavenport@google.com>

drm/VSyncWorker.cpp

diff --git a/drm/VSyncWorker.cpp b/drm/VSyncWorker.cpp
index c120af6..6123e5c 100644
--- a/drm/VSyncWorker.cpp
+++ b/drm/VSyncWorker.cpp
@@ -78,6 +78,12 @@
   return last_vsync_timestamp_;
 }
 
+void VSyncWorker::SetTimestampCallback(
+    std::optional<VsyncTimestampCallback> &&callback) {
+  const std::lock_guard<std::mutex> lock(mutex_);
+  callback_ = std::move(callback);
+}
+
 void VSyncWorker::StopThread() {
   {
     const std::lock_guard<std::mutex> lock(mutex_);
@@ -173,6 +179,7 @@
     }
 
     decltype(callbacks_.out_event) callback;
+    std::optional<VsyncTimestampCallback> vsync_callback;
 
     {
       const std::lock_guard<std::mutex> lock(mutex_);
@@ -182,6 +189,11 @@
       if (enable_vsync_timestamps_) {
         last_vsync_timestamp_ = timestamp;
       }
+      vsync_callback = callback_;
+    }
+
+    if (vsync_callback) {
+      vsync_callback.value()(timestamp, vsync_period_ns_);
     }
 
     if (callback)

drm/VSyncWorker.h

diff --git a/drm/VSyncWorker.h b/drm/VSyncWorker.h
index f0367ae..f032d79 100644
--- a/drm/VSyncWorker.h
+++ b/drm/VSyncWorker.h
@@ -32,6 +32,9 @@
 
 class VSyncWorker {
  public:
+  using VsyncTimestampCallback = std::function<void(int64_t /*timestamp*/,
+                                                    uint32_t /*period*/)>;
+
   ~VSyncWorker() = default;
 
   auto static CreateInstance(std::shared_ptr<DrmDisplayPipeline> &pipe,
@@ -43,6 +46,9 @@
   // Set the expected vsync period.
   void SetVsyncPeriodNs(uint32_t vsync_period_ns);
 
+  // Set or clear a callback to be fired on vsync.
+  void SetTimestampCallback(std::optional<VsyncTimestampCallback> &&callback);
+
   // Enable vsync timestamp tracking. GetLastVsyncTimestamp will return 0 if
   // vsync tracking is disabled, or if no vsync has happened since it was
   // enabled.
@@ -74,6 +80,7 @@
   uint32_t vsync_period_ns_ = kDefaultVSPeriodNs;
   bool enable_vsync_timestamps_ = false;
   uint32_t last_vsync_timestamp_ = 0;
+  std::optional<VsyncTimestampCallback> callback_;
 
   std::condition_variable cv_;
   std::thread vswt_;