commit 33121b799af86e837114c524428ff9ac89a0f7bc
author Drew Davenport <ddavenport@google.com> Fri Dec 13 14:59:35 2024 -0700
committer Drew Davenport <ddavenport@google.com> Mon Dec 16 17:53:16 2024 -0700
tree f400a7ef4fca480cb981acb100ac8b7090d5baf2
parent d387c849400891fdd34752f5fc9d515dad0f384a

drm_hwcomposer: Move vsync tracking into VSyncWorker

Track the timestamp of the last vsync event in VSyncWorker, and provide
an interface for HwcDisplay to enable/disable tracking, and to query the
most recent timestamp.

Moving this into VSyncWorker avoids the need for the VSyncWorker thread
to acquire the global lock.

Change-Id: Ib79d9a6dc5e0f7d6a36ca01dbcda5434a0f582a4
Signed-off-by: Drew Davenport <ddavenport@google.com>

drm/VSyncWorker.cpp

diff --git a/drm/VSyncWorker.cpp b/drm/VSyncWorker.cpp
index 851e87c..c120af6 100644
--- a/drm/VSyncWorker.cpp
+++ b/drm/VSyncWorker.cpp
@@ -63,6 +63,21 @@
   vsync_period_ns_ = vsync_period_ns;
 }
 
+void VSyncWorker::SetVsyncTimestampTracking(bool enabled) {
+  const std::lock_guard<std::mutex> lock(mutex_);
+  enable_vsync_timestamps_ = enabled;
+  if (enabled) {
+    // Reset the last timestamp so the caller knows if a vsync timestamp is
+    // fresh or not.
+    last_vsync_timestamp_ = 0;
+  }
+}
+
+uint32_t VSyncWorker::GetLastVsyncTimestamp() {
+  const std::lock_guard<std::mutex> lock(mutex_);
+  return last_vsync_timestamp_;
+}
+
 void VSyncWorker::StopThread() {
   {
     const std::lock_guard<std::mutex> lock(mutex_);
@@ -164,6 +179,9 @@
       if (!enabled_)
         continue;
       callback = callbacks_.out_event;
+      if (enable_vsync_timestamps_) {
+        last_vsync_timestamp_ = timestamp;
+      }
     }
 
     if (callback)

drm/VSyncWorker.h

diff --git a/drm/VSyncWorker.h b/drm/VSyncWorker.h
index aff34d8..f0367ae 100644
--- a/drm/VSyncWorker.h
+++ b/drm/VSyncWorker.h
@@ -43,6 +43,12 @@
   // Set the expected vsync period.
   void SetVsyncPeriodNs(uint32_t vsync_period_ns);
 
+  // Enable vsync timestamp tracking. GetLastVsyncTimestamp will return 0 if
+  // vsync tracking is disabled, or if no vsync has happened since it was
+  // enabled.
+  void SetVsyncTimestampTracking(bool enabled);
+  uint32_t GetLastVsyncTimestamp();
+
   void StopThread();
 
  private:
@@ -66,6 +72,8 @@
   static constexpr uint32_t kDefaultVSPeriodNs = 16666666;
   // Needs to be threadsafe.
   uint32_t vsync_period_ns_ = kDefaultVSPeriodNs;
+  bool enable_vsync_timestamps_ = false;
+  uint32_t last_vsync_timestamp_ = 0;
 
   std::condition_variable cv_;
   std::thread vswt_;