diff --git a/current.txt b/current.txt
index 7ef176bab0..073beb7681 100644
--- a/current.txt
+++ b/current.txt
@@ -769,6 +769,7 @@ a64467bae843569f0d465c5be7f0c7a5b987985b55a3ef4794dd5afc68538650 android.hardwar
 # ABI preserving changes to HALs during Android S
 1ca372cd67d197df099e87616a613ba6ede6552638a603e18f86c8834302c3d1 android.hardware.gnss@1.0::IGnssMeasurementCallback
 6a271e493907e8ba20912e42771bd0d99ae45431a851d5675ef9496d02510a34 android.hardware.gnss@1.1::IGnssMeasurementCallback
+2c331a9605f3a08d9c1e0a36169ca57758bc43c11a78ef3f3730509885e52c15 android.hardware.graphics.composer@2.4::IComposerClient
 3da3ce039247872d95c6bd48621dbfdfa1c2d2a91a90f257862f87ee2bc46300 android.hardware.health@2.1::types
 cd84ab19c590e0e73dd2307b591a3093ee18147ef95e6d5418644463a6620076 android.hardware.neuralnetworks@1.2::IDevice
 9625e85f56515ad2cf87b6a1847906db669f746ea4ab02cd3d4ca25abc9b0109 android.hardware.neuralnetworks@1.2::types
diff --git a/graphics/composer/2.4/IComposerClient.hal b/graphics/composer/2.4/IComposerClient.hal
index 9e3cf0e083..1a59bbde80 100644
--- a/graphics/composer/2.4/IComposerClient.hal
+++ b/graphics/composer/2.4/IComposerClient.hal
@@ -34,7 +34,9 @@ interface IComposerClient extends @2.3::IComposerClient {
         /**
          * The configuration group ID (as int32_t) this config is associated to.
          * Switching between configurations within the same group may be done seamlessly
-         * in some conditions via setActiveConfigWithConstraints.
+         * in some conditions via setActiveConfigWithConstraints. Configurations which
+         * share the same config group are similar in all attributes except for the
+         * vsync period.
          */
         CONFIG_GROUP = 7,
     };