From dc6dd69948498538c8668de47f53cb576250dc59 Mon Sep 17 00:00:00 2001
From: Ady Abraham <adyabr@google.com>
Date: Tue, 21 Dec 2021 18:10:46 -0800
Subject: [PATCH] composer: release fence can be null

Add @nullable to the releaseFence in IComposerClient.setReadbackBuffer
as it can be null, if the buffer is ready to be consumed.

Bug: 210166943
Test: VTS
Change-Id: Ic556ceabd22ba8acddf37ca7d9a6d14d41697c5b
---
 .../graphics/composer3/IComposerClient.aidl         |  4 ++--
 .../graphics/composer3/IComposerClient.aidl         | 13 ++++++++-----
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/graphics/composer/aidl/aidl_api/android.hardware.graphics.composer3/current/android/hardware/graphics/composer3/IComposerClient.aidl b/graphics/composer/aidl/aidl_api/android.hardware.graphics.composer3/current/android/hardware/graphics/composer3/IComposerClient.aidl
index 2bdbc9fd96..36f701ce2b 100644
--- a/graphics/composer/aidl/aidl_api/android.hardware.graphics.composer3/current/android/hardware/graphics/composer3/IComposerClient.aidl
+++ b/graphics/composer/aidl/aidl_api/android.hardware.graphics.composer3/current/android/hardware/graphics/composer3/IComposerClient.aidl
@@ -56,7 +56,7 @@ interface IComposerClient {
   int getMaxVirtualDisplayCount();
   android.hardware.graphics.composer3.PerFrameMetadataKey[] getPerFrameMetadataKeys(long display);
   android.hardware.graphics.composer3.ReadbackBufferAttributes getReadbackBufferAttributes(long display);
-  ParcelFileDescriptor getReadbackBufferFence(long display);
+  @nullable ParcelFileDescriptor getReadbackBufferFence(long display);
   android.hardware.graphics.composer3.RenderIntent[] getRenderIntents(long display, android.hardware.graphics.composer3.ColorMode mode);
   android.hardware.graphics.composer3.ContentType[] getSupportedContentTypes(long display);
   void registerCallback(in android.hardware.graphics.composer3.IComposerCallback callback);
@@ -69,7 +69,7 @@ interface IComposerClient {
   void setDisplayBrightness(long display, float brightness);
   void setDisplayedContentSamplingEnabled(long display, boolean enable, android.hardware.graphics.composer3.FormatColorComponent componentMask, long maxFrames);
   void setPowerMode(long display, android.hardware.graphics.composer3.PowerMode mode);
-  void setReadbackBuffer(long display, in android.hardware.common.NativeHandle buffer, in ParcelFileDescriptor releaseFence);
+  void setReadbackBuffer(long display, in android.hardware.common.NativeHandle buffer, in @nullable ParcelFileDescriptor releaseFence);
   void setVsyncEnabled(long display, boolean enabled);
   const int EX_BAD_CONFIG = 1;
   const int EX_BAD_DISPLAY = 2;
diff --git a/graphics/composer/aidl/android/hardware/graphics/composer3/IComposerClient.aidl b/graphics/composer/aidl/android/hardware/graphics/composer3/IComposerClient.aidl
index 28bdb2c44e..1b198924fb 100644
--- a/graphics/composer/aidl/android/hardware/graphics/composer3/IComposerClient.aidl
+++ b/graphics/composer/aidl/android/hardware/graphics/composer3/IComposerClient.aidl
@@ -479,7 +479,7 @@ interface IComposerClient {
      *   getReadbackBufferAttributes
      *   setReadbackBuffer
      */
-    ParcelFileDescriptor getReadbackBufferFence(long display);
+    @nullable ParcelFileDescriptor getReadbackBufferFence(long display);
 
     /**
      * Returns the render intents supported by the specified display and color
@@ -702,13 +702,15 @@ interface IComposerClient {
      * This buffer must have been allocated as described in
      * getReadbackBufferAttributes and is in the dataspace provided by the same.
      *
+     * Also provides a file descriptor referring to a release sync fence
+     * object, which must be signaled when it is safe to write to the readback
+     * buffer. If it is already safe to write to the readback buffer, null may be passed instead.
+     *
      * If there is hardware protected content on the display at the time of the next
      * composition, the area of the readback buffer covered by such content must be
      * completely black. Any areas of the buffer not covered by such content may
      * optionally be black as well.
      *
-     * The release fence file descriptor provided works identically to the one
-     * described for setOutputBuffer.
      *
      * This function must not be called between any call to validateDisplay and a
      * subsequent call to presentDisplay.
@@ -716,7 +718,8 @@ interface IComposerClient {
      * Parameters:
      * @param display - the display on which to create the layer.
      * @param buffer - the new readback buffer
-     * @param releaseFence - a sync fence file descriptor as described in setOutputBuffer
+     * @param releaseFence - a sync fence file descriptor as described above or null if it is
+     *                       already safe to write to the readback buffer.
      *
      * @exception EX_BAD_DISPLAY - an invalid display handle was passed in
      * @exception EX_BAD_PARAMETER - the new readback buffer handle was invalid
@@ -726,7 +729,7 @@ interface IComposerClient {
      *   getReadbackBufferFence
      */
     void setReadbackBuffer(long display, in android.hardware.common.NativeHandle buffer,
-            in ParcelFileDescriptor releaseFence);
+            in @nullable ParcelFileDescriptor releaseFence);
 
     /**
      * Enables or disables the vsync signal for the given display. Virtual