Allow to apply first brightness as -1

The initial brightness is -1 in DisplayDevice. It won't apply
the brightness(-1) for the first brightness. This allow an
caller to set the brightness to -1

Bug: 254657816
test: atest libsurfaceflinger_unittest:SetDisplayBrightnessTest
Change-Id: I3a87d0b505b8bf8ce411c86a061376aadba42a88
Merged-In: I3a87d0b505b8bf8ce411c86a061376aadba42a88

3 files changed, 22 insertions, 4 deletions

diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index 86ad4ef169..b49c95d677 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -174,7 +174,7 @@ auto DisplayDevice::getInputInfo() const -> InputInfo {
 
 void DisplayDevice::setPowerMode(hal::PowerMode mode) {
     if (mode == hal::PowerMode::OFF || mode == hal::PowerMode::ON) {
-        if (mStagedBrightness && mBrightness != *mStagedBrightness) {
+        if (mStagedBrightness && mBrightness != mStagedBrightness) {
             getCompositionDisplay()->setNextBrightness(*mStagedBrightness);
             mBrightness = *mStagedBrightness;
         }
@@ -336,7 +336,7 @@ void DisplayDevice::stageBrightness(float brightness) {
 }
 
 void DisplayDevice::persistBrightness(bool needsComposite) {
-    if (mStagedBrightness && mBrightness != *mStagedBrightness) {
+    if (mStagedBrightness && mBrightness != mStagedBrightness) {
         if (needsComposite) {
             getCompositionDisplay()->setNextBrightness(*mStagedBrightness);
         }
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index f14bef3d11..b91dece909 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -284,8 +284,8 @@ private:
      // allow initial power mode as null.
     std::optional<hardware::graphics::composer::hal::PowerMode> mPowerMode;
     DisplayModePtr mActiveMode;
-    std::optional<float> mStagedBrightness = std::nullopt;
-    float mBrightness = -1.f;
+    std::optional<float> mStagedBrightness;
+    std::optional<float> mBrightness;
     const DisplayModes mSupportedModes;
 
     std::atomic<nsecs_t> mLastHwVsync = 0;
diff --git a/services/surfaceflinger/tests/unittests/DisplayDevice_SetDisplayBrightnessTest.cpp b/services/surfaceflinger/tests/unittests/DisplayDevice_SetDisplayBrightnessTest.cpp
index 225ad163d9..ac5e9274bb 100644
--- a/services/surfaceflinger/tests/unittests/DisplayDevice_SetDisplayBrightnessTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayDevice_SetDisplayBrightnessTest.cpp
@@ -96,5 +96,23 @@ TEST_F(SetDisplayBrightnessTest, persistDisplayBrightnessWithCompositeShortCircu
     EXPECT_EQ(std::nullopt, displayDevice->getCompositionDisplay()->getState().displayBrightness);
 }
 
+TEST_F(SetDisplayBrightnessTest, firstDisplayBrightnessWithComposite) {
+    ftl::FakeGuard guard(kMainThreadContext);
+    sp<DisplayDevice> displayDevice = getDisplayDevice();
+
+    EXPECT_EQ(std::nullopt, displayDevice->getStagedBrightness());
+
+    constexpr float kDisplayBrightness = -1.0f;
+    displayDevice->stageBrightness(kDisplayBrightness);
+
+    EXPECT_EQ(-1.0f, displayDevice->getStagedBrightness());
+
+    displayDevice->persistBrightness(true);
+
+    EXPECT_EQ(std::nullopt, displayDevice->getStagedBrightness());
+    EXPECT_EQ(kDisplayBrightness,
+              displayDevice->getCompositionDisplay()->getState().displayBrightness);
+}
+
 } // namespace
 } // namespace android