diff --git a/evs/1.0/default/EvsCamera.cpp b/evs/1.0/default/EvsCamera.cpp
index 32d4ed7..6715a2e 100644
--- a/evs/1.0/default/EvsCamera.cpp
+++ b/evs/1.0/default/EvsCamera.cpp
@@ -48,14 +48,14 @@
 
     // Set up dummy data for testing
     if (mDescription.cameraId == kCameraName_Backup) {
-        mDescription.hints                  = UsageHint::USAGE_HINT_REVERSE;
+        mDescription.hints                  = static_cast<uint32_t>(UsageHint::USAGE_HINT_REVERSE);
         mDescription.vendorFlags            = 0xFFFFFFFF;   // Arbitrary value
         mDescription.defaultHorResolution   = 320;          // 1/2 NTSC/VGA
         mDescription.defaultVerResolution   = 240;          // 1/2 NTSC/VGA
     }
     else if (mDescription.cameraId == kCameraName_RightTurn) {
         // Nothing but the name and the usage hint
-        mDescription.hints                  = UsageHint::USAGE_HINT_RIGHT_TURN;
+        mDescription.hints                  = static_cast<uint32_t>(UsageHint::USAGE_HINT_RIGHT_TURN);
     }
     else {
         // Leave empty for a minimalist camera description without even a hint
@@ -149,7 +149,7 @@
     return EvsResult::OK;
 }
 
-Return<EvsResult> EvsCamera::doneWithFrame(uint32_t frameId, const hidl_handle& bufferHandle)  {
+Return<EvsResult> EvsCamera::doneWithFrame(uint32_t /* frameId */, const hidl_handle& bufferHandle)  {
     ALOGD("doneWithFrame");
     std::lock_guard<std::mutex> lock(mAccessLock);
 
diff --git a/evs/1.0/types.hal b/evs/1.0/types.hal
index e0051e1..fd9dcdc 100644
--- a/evs/1.0/types.hal
+++ b/evs/1.0/types.hal
@@ -32,7 +32,6 @@
     USAGE_HINT_REVERSE      = 0x00000001,
     USAGE_HINT_LEFT_TURN    = 0x00000002,
     USAGE_HINT_RIGHT_TURN   = 0x00000004,
-    // remaining bits are reserved for future use
 };
 
 
@@ -48,11 +47,11 @@
  * should be set to ZERO.
  */
 struct CameraDesc {
-    string      cameraId;
-    UsageHint   hints;                  // Bit flags (legal to | values together) (TODO: b/31702236)
-    uint32_t    vendorFlags;            // Opaque value from driver
-    uint32_t    defaultHorResolution;   // Units of pixels
-    uint32_t    defaultVerResolution;   // Units of pixels
+    string              cameraId;
+    bitfield<UsageHint> hints;                  // Mask of usage hints
+    uint32_t            vendorFlags;            // Opaque value from driver
+    uint32_t            defaultHorResolution;   // Units of pixels
+    uint32_t            defaultVerResolution;   // Units of pixels
 };
 
 
@@ -90,7 +89,6 @@
 
 
 /* Error codes used in EVS HAL interface. */
-/* TODO:  Adopt a common set of function return codes */
 enum EvsResult : uint32_t {
     OK = 0,
     INVALID_ARG,