diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
index 9a9a5c3..741eb7c 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.cpp
@@ -905,23 +905,25 @@
     return Error::NONE;
 }
 
-Error Composer::getPerFrameMetadataKeys(
-        Display display, std::vector<IComposerClient::PerFrameMetadataKey>* outKeys) {
+std::vector<IComposerClient::PerFrameMetadataKey> Composer::getPerFrameMetadataKeys(
+        Display display) {
+    std::vector<IComposerClient::PerFrameMetadataKey>  keys;
     if (!mClient_2_2) {
-        return Error::UNSUPPORTED;
+        return keys;
     }
 
     Error error = kDefaultError;
     mClient_2_2->getPerFrameMetadataKeys(display, [&](const auto& tmpError, const auto& tmpKeys) {
         error = tmpError;
         if (error != Error::NONE) {
+            ALOGW("getPerFrameMetadataKeys failed with %d", tmpError);
             return;
         }
 
-        *outKeys = tmpKeys;
+        keys = tmpKeys;
     });
 
-    return error;
+    return keys;
 }
 
 Error Composer::getRenderIntents(Display display, ColorMode colorMode,
diff --git a/services/surfaceflinger/DisplayHardware/ComposerHal.h b/services/surfaceflinger/DisplayHardware/ComposerHal.h
index bd18b09..60b0f72 100644
--- a/services/surfaceflinger/DisplayHardware/ComposerHal.h
+++ b/services/surfaceflinger/DisplayHardware/ComposerHal.h
@@ -182,8 +182,8 @@
     virtual Error setLayerPerFrameMetadata(
             Display display, Layer layer,
             const std::vector<IComposerClient::PerFrameMetadata>& perFrameMetadatas) = 0;
-    virtual Error getPerFrameMetadataKeys(
-            Display display, std::vector<IComposerClient::PerFrameMetadataKey>* outKeys) = 0;
+    virtual std::vector<IComposerClient::PerFrameMetadataKey> getPerFrameMetadataKeys(
+            Display display) = 0;
     virtual Error getRenderIntents(Display display, ColorMode colorMode,
             std::vector<RenderIntent>* outRenderIntents) = 0;
     virtual Error getDataspaceSaturationMatrix(Dataspace dataspace, mat4* outMatrix) = 0;
@@ -380,8 +380,8 @@
     Error setLayerPerFrameMetadata(
             Display display, Layer layer,
             const std::vector<IComposerClient::PerFrameMetadata>& perFrameMetadatas) override;
-    Error getPerFrameMetadataKeys(
-            Display display, std::vector<IComposerClient::PerFrameMetadataKey>* outKeys) override;
+    std::vector<IComposerClient::PerFrameMetadataKey> getPerFrameMetadataKeys(
+            Display display) override;
     Error getRenderIntents(Display display, ColorMode colorMode,
             std::vector<RenderIntent>* outRenderIntents) override;
     Error getDataspaceSaturationMatrix(Dataspace dataspace, mat4* outMatrix) override;
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.cpp b/services/surfaceflinger/DisplayHardware/HWC2.cpp
index add93fd..ef31908 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWC2.cpp
@@ -409,21 +409,17 @@
     return static_cast<Error>(intError);
 }
 
-Error Display::getSupportedPerFrameMetadata(int32_t* outSupportedPerFrameMetadata) const
+int32_t Display::getSupportedPerFrameMetadata() const
 {
-    *outSupportedPerFrameMetadata = 0;
-    std::vector<Hwc2::PerFrameMetadataKey> tmpKeys;
-    auto intError = mComposer.getPerFrameMetadataKeys(mId, &tmpKeys);
-    auto error = static_cast<Error>(intError);
-    if (error != Error::None) {
-        return error;
-    }
+    int32_t supportedPerFrameMetadata = 0;
+
+    std::vector<Hwc2::PerFrameMetadataKey> tmpKeys = mComposer.getPerFrameMetadataKeys(mId);
+    std::set<Hwc2::PerFrameMetadataKey> keys(tmpKeys.begin(), tmpKeys.end());
 
     // Check whether a specific metadata type is supported. A metadata type is considered
     // supported if and only if all required fields are supported.
 
     // SMPTE2086
-    std::set<Hwc2::PerFrameMetadataKey> keys(tmpKeys.begin(), tmpKeys.end());
     if (hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::DISPLAY_RED_PRIMARY_X) &&
         hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::DISPLAY_RED_PRIMARY_Y) &&
         hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::DISPLAY_GREEN_PRIMARY_X) &&
@@ -434,15 +430,15 @@
         hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::WHITE_POINT_Y) &&
         hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::MAX_LUMINANCE) &&
         hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::MIN_LUMINANCE)) {
-        *outSupportedPerFrameMetadata |= HdrMetadata::Type::SMPTE2086;
+        supportedPerFrameMetadata |= HdrMetadata::Type::SMPTE2086;
     }
     // CTA861_3
     if (hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::MAX_CONTENT_LIGHT_LEVEL) &&
         hasMetadataKey(keys, Hwc2::PerFrameMetadataKey::MAX_FRAME_AVERAGE_LIGHT_LEVEL)) {
-        *outSupportedPerFrameMetadata |= HdrMetadata::Type::CTA861_3;
+        supportedPerFrameMetadata |= HdrMetadata::Type::CTA861_3;
     }
 
-    return Error::None;
+    return supportedPerFrameMetadata;
 }
 
 Error Display::getRenderIntents(ColorMode colorMode,
diff --git a/services/surfaceflinger/DisplayHardware/HWC2.h b/services/surfaceflinger/DisplayHardware/HWC2.h
index 532685c..900b3d7 100644
--- a/services/surfaceflinger/DisplayHardware/HWC2.h
+++ b/services/surfaceflinger/DisplayHardware/HWC2.h
@@ -218,10 +218,8 @@
             std::unordered_map<Layer*, Composition>* outTypes);
     [[clang::warn_unused_result]] Error getColorModes(
             std::vector<android::ui::ColorMode>* outModes) const;
-    // outSupportedPerFrameMetadata is an opaque bitmask to the callers
-    // but contains HdrMetadata::Type::*.
-    [[clang::warn_unused_result]] Error getSupportedPerFrameMetadata(
-            int32_t* outSupportedPerFrameMetadata) const;
+    // Returns a bitmask which contains HdrMetadata::Type::*.
+    [[clang::warn_unused_result]] int32_t getSupportedPerFrameMetadata() const;
     [[clang::warn_unused_result]] Error getRenderIntents(
             android::ui::ColorMode colorMode,
             std::vector<android::ui::RenderIntent>* outRenderIntents) const;
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 8b7bca7..bf8905a 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -745,12 +745,7 @@
 
 int32_t HWComposer::getSupportedPerFrameMetadata(int32_t displayId) const {
     RETURN_IF_INVALID_DISPLAY(displayId, 0);
-
-    int32_t supportedMetadata;
-    auto error = mDisplayData[displayId].hwcDisplay->getSupportedPerFrameMetadata(
-            &supportedMetadata);
-    RETURN_IF_HWC_ERROR(error, displayId, 0);
-    return supportedMetadata;
+    return mDisplayData[displayId].hwcDisplay->getSupportedPerFrameMetadata();
 }
 
 std::vector<ui::RenderIntent> HWComposer::getRenderIntents(int32_t displayId,
diff --git a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
index 0f28a7d..58d3879 100644
--- a/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
+++ b/services/surfaceflinger/tests/unittests/DisplayTransactionTest.cpp
@@ -577,7 +577,7 @@
 struct NonHwcPerFrameMetadataSupportVariant {
     static constexpr int PER_FRAME_METADATA_KEYS = 0;
     static void setupComposerCallExpectations(DisplayTransactionTest* test) {
-        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(_, _)).Times(0);
+        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(_)).Times(0);
     }
 };
 
@@ -585,9 +585,8 @@
 struct NoPerFrameMetadataSupportVariant {
     static constexpr int PER_FRAME_METADATA_KEYS = 0;
     static void setupComposerCallExpectations(DisplayTransactionTest* test) {
-        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(Display::HWC_DISPLAY_ID, _))
-                .WillOnce(DoAll(SetArgPointee<1>(std::vector<PerFrameMetadataKey>()),
-                                Return(Error::NONE)));
+        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(Display::HWC_DISPLAY_ID))
+                .WillOnce(Return(std::vector<PerFrameMetadataKey>()));
     }
 };
 
@@ -595,8 +594,8 @@
 struct Smpte2086PerFrameMetadataSupportVariant {
     static constexpr int PER_FRAME_METADATA_KEYS = HdrMetadata::Type::SMPTE2086;
     static void setupComposerCallExpectations(DisplayTransactionTest* test) {
-        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(Display::HWC_DISPLAY_ID, _))
-                .WillOnce(DoAll(SetArgPointee<1>(std::vector<PerFrameMetadataKey>({
+        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(Display::HWC_DISPLAY_ID))
+                .WillOnce(Return(std::vector<PerFrameMetadataKey>({
                                         PerFrameMetadataKey::DISPLAY_RED_PRIMARY_X,
                                         PerFrameMetadataKey::DISPLAY_RED_PRIMARY_Y,
                                         PerFrameMetadataKey::DISPLAY_GREEN_PRIMARY_X,
@@ -607,8 +606,7 @@
                                         PerFrameMetadataKey::WHITE_POINT_Y,
                                         PerFrameMetadataKey::MAX_LUMINANCE,
                                         PerFrameMetadataKey::MIN_LUMINANCE,
-                                })),
-                                Return(Error::NONE)));
+                                })));
     }
 };
 
@@ -616,12 +614,11 @@
 struct Cta861_3_PerFrameMetadataSupportVariant {
     static constexpr int PER_FRAME_METADATA_KEYS = HdrMetadata::Type::CTA861_3;
     static void setupComposerCallExpectations(DisplayTransactionTest* test) {
-        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(Display::HWC_DISPLAY_ID, _))
-                .WillOnce(DoAll(SetArgPointee<1>(std::vector<PerFrameMetadataKey>({
+        EXPECT_CALL(*test->mComposer, getPerFrameMetadataKeys(Display::HWC_DISPLAY_ID))
+                .WillOnce(Return(std::vector<PerFrameMetadataKey>({
                                         PerFrameMetadataKey::MAX_CONTENT_LIGHT_LEVEL,
                                         PerFrameMetadataKey::MAX_FRAME_AVERAGE_LIGHT_LEVEL,
-                                })),
-                                Return(Error::NONE)));
+                                })));
     }
 };
 
diff --git a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
index 2a707a4..b9e0715 100644
--- a/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
+++ b/services/surfaceflinger/tests/unittests/mock/DisplayHardware/MockComposer.h
@@ -74,8 +74,8 @@
     MOCK_METHOD2(getDisplayType, Error(Display, IComposerClient::DisplayType*));
     MOCK_METHOD2(getDozeSupport, Error(Display, bool*));
     MOCK_METHOD5(getHdrCapabilities, Error(Display, std::vector<Hdr>*, float*, float*, float*));
-    MOCK_METHOD2(getPerFrameMetadataKeys,
-                 Error(Display, std::vector<IComposerClient::PerFrameMetadataKey>*));
+    MOCK_METHOD1(getPerFrameMetadataKeys,
+                 std::vector<IComposerClient::PerFrameMetadataKey>(Display));
     MOCK_METHOD2(getDataspaceSaturationMatrix, Error(Dataspace, mat4*));
     MOCK_METHOD3(getDisplayIdentificationData, Error(Display, uint8_t*, std::vector<uint8_t>*));
     MOCK_METHOD3(getReleaseFences, Error(Display, std::vector<Layer>*, std::vector<int>*));