commit d387c849400891fdd34752f5fc9d515dad0f384a
author Drew Davenport <ddavenport@google.com> Mon Dec 16 16:57:24 2024 -0700
committer Drew Davenport <ddavenport@google.com> Mon Dec 16 17:53:10 2024 -0700
tree 3c54eca24229f92e16197b783d3b8c1567d601f9
parent edccc0b7e4fa888857be6846f36b30d94c8d0150

drm_hwcomposer: Simplify default vsync period

VSyncWorker::SetVsyncPeriod won't be called with a value of 0, so the
only time the internal vsync period will be zero is if SetVsyncPeriod
was not called.

Set the 60Hz vsync period as a default value, and let the synthetic
vsync code expect it to be set to a reasonable value.

Change-Id: Ie1f83b0c11504acf304cc241923bfa60a5ffd647
Signed-off-by: Drew Davenport <ddavenport@google.com>

drm/VSyncWorker.cpp

diff --git a/drm/VSyncWorker.cpp b/drm/VSyncWorker.cpp
index f4c0710..851e87c 100644
--- a/drm/VSyncWorker.cpp
+++ b/drm/VSyncWorker.cpp
@@ -100,11 +100,7 @@
 int VSyncWorker::SyntheticWaitVBlank(int64_t *timestamp) {
   auto time_now = ResourceManager::GetTimeMonotonicNs();
 
-  // Default to 60Hz refresh rate
-  constexpr uint32_t kDefaultVSPeriodNs = 16666666;
-  auto period_ns = vsync_period_ns_ ? vsync_period_ns_ : kDefaultVSPeriodNs;
-
-  auto phased_timestamp = GetPhasedVSync(period_ns, time_now);
+  auto phased_timestamp = GetPhasedVSync(vsync_period_ns_, time_now);
   struct timespec vsync {};
   vsync.tv_sec = int(phased_timestamp / kOneSecondNs);
   vsync.tv_nsec = int(phased_timestamp - (vsync.tv_sec * kOneSecondNs));

drm/VSyncWorker.h

diff --git a/drm/VSyncWorker.h b/drm/VSyncWorker.h
index 2ee7f37..aff34d8 100644
--- a/drm/VSyncWorker.h
+++ b/drm/VSyncWorker.h
@@ -62,8 +62,10 @@
   bool thread_exit_ = false;
   int64_t last_timestamp_ = -1;
 
+  // Default to 60Hz refresh rate
+  static constexpr uint32_t kDefaultVSPeriodNs = 16666666;
   // Needs to be threadsafe.
-  uint32_t vsync_period_ns_ = 0;
+  uint32_t vsync_period_ns_ = kDefaultVSPeriodNs;
 
   std::condition_variable cv_;
   std::thread vswt_;

hwc2_device/HwcDisplay.cpp

diff --git a/hwc2_device/HwcDisplay.cpp b/hwc2_device/HwcDisplay.cpp
index f3c0fa0..2260e36 100644
--- a/hwc2_device/HwcDisplay.cpp
+++ b/hwc2_device/HwcDisplay.cpp
@@ -680,7 +680,7 @@
   uint32_t prev_vperiod_ns = 0;
   GetDisplayVsyncPeriod(&prev_vperiod_ns);
 
-  auto mode_update_commited_ = false;
+  std::optional<uint32_t> new_vsync_period_ns;
   if (staged_mode_config_id_ &&
       staged_mode_change_time_ <= ResourceManager::GetTimeMonotonicNs()) {
     const HwcDisplayConfig *staged_config = GetConfig(
@@ -697,7 +697,7 @@
     configs_.active_config_id = staged_mode_config_id_.value();
     a_args.display_mode = staged_config->mode;
     if (!a_args.test_only) {
-      mode_update_commited_ = true;
+      new_vsync_period_ns = staged_config->mode.GetVSyncPeriodNs();
     }
   }
 
@@ -773,12 +773,8 @@
     return HWC2::Error::BadParameter;
   }
 
-  if (mode_update_commited_) {
-    const HwcDisplayConfig *new_config = GetCurrentConfig();
-    uint32_t new_vsync_period_ns = new_config
-                                       ? new_config->mode.GetVSyncPeriodNs()
-                                       : 0;
-    vsync_worker_->SetVsyncPeriodNs(new_vsync_period_ns);
+  if (new_vsync_period_ns) {
+    vsync_worker_->SetVsyncPeriodNs(new_vsync_period_ns.value());
     staged_mode_config_id_.reset();
     vsync_tracking_en_ = false;
     if (last_vsync_ts_ != 0) {