EGL_ANDROID_fence_sync: make it more generic

This change updates the extension spec to refer to generic "native fence sync
objects" rather than "Android fence sync objects."

Change-Id: I15a79f08571586431845b54c58c8420b652f40ef

1 files changed, 73 insertions, 61 deletions

diff --git a/opengl/specs/EGL_ANDROID_fence_sync.txt b/opengl/specs/EGL_ANDROID_native_fence_sync.txt
index 316ee1c..bd1cdda 100644
--- a/opengl/specs/EGL_ANDROID_fence_sync.txt
+++ b/opengl/specs/EGL_ANDROID_native_fence_sync.txt
@@ -1,10 +1,10 @@
 Name
 
-    ANDROID_fence_sync
+    ANDROID_native_fence_sync
 
 Name Strings
 
-    EGL_ANDROID_fence_sync
+    EGL_ANDROID_native_fence_sync
 
 Contributors
 
@@ -37,10 +37,17 @@ Dependencies
 Overview
 
     This extension enables the creation of EGL fence sync objects that are
-    associated with an Android Sync HAL fence object.  These EGL fence sync
-    objects have nearly identical semantics to those defined by the
-    KHR_fence_sync extension, except that they have an additional attribute
-    storing the file descriptor referring to the native Android fence object.
+    associated with a native synchronization fence object that is referenced
+    using a file descriptor.  These EGL fence sync objects have nearly
+    identical semantics to those defined by the KHR_fence_sync extension,
+    except that they have an additional attribute storing the file descriptor
+    referring to the native fence object.
+
+    This extension assumes the existence of a native fence synchronization
+    object that behaves similarly to an EGL fence sync object.  These native
+    objects must have a signal status like that of an EGLSyncKHR object that
+    indicates whether the fence has ever been signaled.  Once signaled the
+    native object's signal status may not change again.
 
 New Types
 
@@ -48,7 +55,7 @@ New Types
 
 New Procedures and Functions
 
-    EGLint eglDupAndroidFenceFDANDROID(
+    EGLint eglDupNativeFenceFDANDROID(
                         EGLDisplay dpy,
                         EGLSyncKHR);
 
@@ -58,72 +65,72 @@ New Tokens
     in <value> when eglGetSyncAttribKHR is called with <attribute>
     EGL_SYNC_TYPE_KHR:
 
-    EGL_SYNC_ANDROID_FENCE_ANDROID          0x3144
+    EGL_SYNC_NATIVE_FENCE_ANDROID          0x3144
 
     Accepted by the <attrib_list> parameter of eglCreateSyncKHR:
 
-    EGL_SYNC_ANDROID_FENCE_FD_ANDROID       0x3145
+    EGL_SYNC_NATIVE_FENCE_FD_ANDROID       0x3145
 
     Accepted by the <attrib_list> parameter of eglCreateSyncKHR, and returned
-    by eglDupAndroidFenceFDANDROID in the event of an error:
+    by eglDupNativeFenceFDANDROID in the event of an error:
 
-    EGL_NO_ANDROID_FENCE_ANDROID            -1
+    EGL_NO_NATIVE_FENCE_ANDROID            -1
 
     Returned in <value> when eglGetSyncAttribKHR is called with <attribute>
     EGL_SYNC_CONDITION_KHR:
 
-    EGL_SYNC_ANDROID_FENCE_SIGNALED_ANDROID 0x3146
+    EGL_SYNC_NATIVE_FENCE_SIGNALED_ANDROID 0x3146
 
 Changes to Chapter 3 of the EGL 1.2 Specification (EGL Functions and Errors)
 
     Add the following after the sixth paragraph of Section 3.8.1 (Sync
     Objects), added by KHR_fence_sync
 
-    "If <type> is EGL_SYNC_ANDROID_FENCE_ANDROID, an EGL Android fence sync
-    object is created. In this case the EGL_SYNC_ANDROID_FENCE_FD_ANDROID
+    "If <type> is EGL_SYNC_NATIVE_FENCE_ANDROID, an EGL native fence sync
+    object is created. In this case the EGL_SYNC_NATIVE_FENCE_FD_ANDROID
     attribute may optionally be specified. If this attribute is specified, it
-    must be set to either a file descriptor that refers to a native Android
-    fence object or to the value EGL_NO_ANDROID_FENCE_ANDROID.
+    must be set to either a file descriptor that refers to a native fence
+    object or to the value EGL_NO_NATIVE_FENCE_ANDROID.
 
-    The default values for the EGL Android fence sync object attributes are as
+    The default values for the EGL native fence sync object attributes are as
     follows:
 
       Attribute Name                     Initial Attribute Value(s)
       ---------------                    --------------------------
-      EGL_SYNC_TYPE_KHR                  EGL_SYNC_ANDROID_FENCE_ANDROID
+      EGL_SYNC_TYPE_KHR                  EGL_SYNC_NATIVE_FENCE_ANDROID
       EGL_SYNC_STATUS_KHR                EGL_UNSIGNALED_KHR
       EGL_SYNC_CONDITION_KHR             EGL_SYNC_PRIOR_COMMANDS_COMPLETE_KHR
-      EGL_SYNC_ANDROID_FENCE_FD_ANDROID  EGL_NO_ANDROID_FENCE_ANDROID
+      EGL_SYNC_NATIVE_FENCE_FD_ANDROID   EGL_NO_NATIVE_FENCE_ANDROID
 
-    If the EGL_SYNC_ANDROID_FENCE_FD_ANDROID attribute is not
-    EGL_NO_ANDROID_FENCE_ANDROID then the EGL_SYNC_CONDITION_KHR attribute is
-    set to EGL_SYNC_ANDROID_FENCE_SIGNALED_ANDROID and the EGL_SYNC_STATUS_KHR
-    attribute is set to reflect the signal status of the native Android fence
-    object. Additionally, the EGL implementation assumes ownership of the file
+    If the EGL_SYNC_NATIVE_FENCE_FD_ANDROID attribute is not
+    EGL_NO_NATIVE_FENCE_ANDROID then the EGL_SYNC_CONDITION_KHR attribute is
+    set to EGL_SYNC_NATIVE_FENCE_SIGNALED_ANDROID and the EGL_SYNC_STATUS_KHR
+    attribute is set to reflect the signal status of the native fence object.
+    Additionally, the EGL implementation assumes ownership of the file
     descriptor, so the caller must not use it after calling eglCreateSyncKHR."
 
     Modify Section 3.8.1 (Sync Objects), added by KHR_fence_sync, starting at
     the seventh paragraph
 
-    "When a fence sync object is created or when an EGL Android fence sync
-    object is created with the EGL_SYNC_ANDROID_FENCE_FD_ANDROID attribute set
-    to EGL_NO_ANDROID_FENCE_ANDROID, eglCreateSyncKHR also inserts a fence
+    "When a fence sync object is created or when an EGL native fence sync
+    object is created with the EGL_SYNC_NATIVE_FENCE_FD_ANDROID attribute set
+    to EGL_NO_NATIVE_FENCE_ANDROID, eglCreateSyncKHR also inserts a fence
     command into the command stream of the bound client API's current context
     (i.e., the context returned by eglGetCurrentContext), and associates it
     with the newly created sync object.
 
-    After associating the fence command with an EGL Android fence sync object,
+    After associating the fence command with an EGL native fence sync object,
     the next Flush() operation performed by the current client API causes a
-    new native Android fence object to be created, and the
-    EGL_SYNC_ANDROID_FENCE_ANDROID attribute of the EGL Android fence object
-    is set to a file descriptor that refers to the new native Android fence
-    object. This new native Android fence object is signaled when the EGL
-    Android fence sync object is signaled.
+    new native fence object to be created, and the
+    EGL_SYNC_NATIVE_FENCE_ANDROID attribute of the EGL native fence object is
+    set to a file descriptor that refers to the new native fence object. This
+    new native fence object is signaled when the EGL native fence sync object
+    is signaled.
 
     When the condition of the sync object is satisfied by the fence command,
     the sync is signaled by the associated client API context, causing any
-    eglClientWaitSyncKHR commands (see below) blocking on <sync> to unblock. If
-    the sync object is an EGL Android fence sync object then the native Android
+    eglClientWaitSyncKHR commands (see below) blocking on <sync> to unblock.
+    If the sync object is an EGL native fence sync object then the native
     fence object is also signaled when the condition is satisfied. The
     EGL_SYNC_PRIOR_COMMANDS_COMPLETE_KHR condition is satisfied by completion
     of the fence command corresponding to the sync object and all preceding
@@ -132,9 +139,9 @@ Changes to Chapter 3 of the EGL 1.2 Specification (EGL Functions and Errors)
     client API's internal and framebuffer state are fully realized. No other
     state is affected by execution of the fence command.
 
-    The EGL_SYNC_ANDROID_FENCE_SIGNALED_ANDROID condition is satisfied by the
-    signaling of the native Android fence object referred to by the
-    EGL_SYNC_ANDROID_FENCE_FD_ANDROID attribute. When this happens any
+    The EGL_SYNC_NATIVE_FENCE_SIGNALED_ANDROID condition is satisfied by the
+    signaling of the native fence object referred to by the
+    EGL_SYNC_NATIVE_FENCE_FD_ANDROID attribute. When this happens any
     eglClientWaitSyncKHR commands blocking on <sync> unblock."
 
     Modify the list of eglCreateSyncKHR errors in Section 3.8.1 (Sync Objects),
@@ -149,22 +156,22 @@ Changes to Chapter 3 of the EGL 1.2 Specification (EGL Functions and Errors)
       * If <type> is EGL_SYNC_FENCE_KHR and <attrib_list> is neither NULL nor
         empty (containing only EGL_NONE), EGL_NO_SYNC_KHR is returned and an
         EGL_BAD_ATTRIBUTE error is generated.
-      * If <type> is EGL_SYNC_ANDROID_FENCE_ANDROID and <attrib_list> contains
-        an attribute other than EGL_SYNC_ANDROID_FENCE_FD_ANDROID, EGL_NO_SYNC_KHR is
+      * If <type> is EGL_SYNC_NATIVE_FENCE_ANDROID and <attrib_list> contains
+        an attribute other than EGL_SYNC_NATIVE_FENCE_FD_ANDROID, EGL_NO_SYNC_KHR is
         returned and an EGL_BAD_ATTRIBUTE error is generated.
       * If <type> is not a supported type of sync object,
         EGL_NO_SYNC_KHR is returned and an EGL_BAD_ATTRIBUTE error is
         generated.
-      * If <type> is EGL_SYNC_FENCE_KHR or EGL_SYNC_ANDROID_FENCE_ANDROID and
+      * If <type> is EGL_SYNC_FENCE_KHR or EGL_SYNC_NATIVE_FENCE_ANDROID and
         no context is current for the bound API (i.e., eglGetCurrentContext
         returns EGL_NO_CONTEXT), EGL_NO_SYNC_KHR is returned and an
         EGL_BAD_MATCH error is generated.
-      * If <type> is EGL_SYNC_FENCE_KHR or EGL_SYNC_ANDROID_FENCE_ANDROID and
+      * If <type> is EGL_SYNC_FENCE_KHR or EGL_SYNC_NATIVE_FENCE_ANDROID and
         <dpy> does not match the EGLDisplay of the currently bound context for
         the currently bound client API (the EGLDisplay returned by
         eglGetCurrentDisplay()) then EGL_NO_SYNC_KHR is returned and an
         EGL_BAD_MATCH error is generated.
-      * If <type> is EGL_SYNC_FENCE_KHR or EGL_SYNC_ANDROID_FENCE_ANDROID and
+      * If <type> is EGL_SYNC_FENCE_KHR or EGL_SYNC_NATIVE_FENCE_ANDROID and
         the currently bound client API does not support the client API
         extension indicating it can place fence commands, then EGL_NO_SYNC_KHR
         is returned and an EGL_BAD_MATCH error is generated."
@@ -177,7 +184,7 @@ Changes to Chapter 3 of the EGL 1.2 Specification (EGL Functions and Errors)
     EGL_SYNC_TYPE_KHR                  Type of the sync object    All
     EGL_SYNC_STATUS_KHR                Status of the sync object  All
     EGL_SYNC_CONDITION_KHR             Signaling condition        EGL_SYNC_FENCE_KHR and
-                                                                  EGL_SYNC_ANDROID_FENCE_ANDROID only
+                                                                  EGL_SYNC_NATIVE_FENCE_ANDROID only
     "
 
     Modify the second paragraph description of eglDestroySyncKHR in Section
@@ -185,8 +192,8 @@ Changes to Chapter 3 of the EGL 1.2 Specification (EGL Functions and Errors)
 
     "If no errors are generated, EGL_TRUE is returned, and <sync> will no
     longer be the handle of a valid sync object.  Additionally, if <sync> is an
-    EGL Android fence sync object and the EGL_SYNC_ANDROID_FENCE_FD_ANDROID
-    attribute is not EGL_NO_ANDROID_FENCE_ANDROID then that file descriptor is
+    EGL native fence sync object and the EGL_SYNC_NATIVE_FENCE_FD_ANDROID
+    attribute is not EGL_NO_NATIVE_FENCE_ANDROID then that file descriptor is
     closed."
 
     Add the following after the last paragraph of Section 3.8.1 (Sync
@@ -194,51 +201,50 @@ Changes to Chapter 3 of the EGL 1.2 Specification (EGL Functions and Errors)
 
     The command
 
-        EGLint eglDupAndroidFenceFDANDROID(
+        EGLint eglDupNativeFenceFDANDROID(
                             EGLdisplay dpy,
                             EGLSyncKHR sync);
 
     duplicates the file descriptor stored in the
-    EGL_SYNC_ANDROID_FENCE_FD_ANDROID attribute of an EGL Android fence sync
+    EGL_SYNC_NATIVE_FENCE_FD_ANDROID attribute of an EGL native fence sync
     object and returns the new file descriptor.
 
     Errors
     ------
 
       * If <sync> is not a valid sync object for <dpy>,
-        EGL_NO_ANDROID_FENCE_ANDROID is returned and an EGL_BAD_PARAMETER
+        EGL_NO_NATIVE_FENCE_ANDROID is returned and an EGL_BAD_PARAMETER
         error is generated.
-      * If the EGL_SYNC_ANDROID_FENCE_FD_ANDROID attribute of <sync> is
-        EGL_NO_ANDROID_FENCE_ANDROID, EGL_NO_ANDROID_FENCE_ANDROID is returned
+      * If the EGL_SYNC_NATIVE_FENCE_FD_ANDROID attribute of <sync> is
+        EGL_NO_NATIVE_FENCE_ANDROID, EGL_NO_NATIVE_FENCE_ANDROID is returned
         and an EGL_BAD_PARAMETER error is generated.
       * If <dpy> does not match the display passed to eglCreateSyncKHR
         when <sync> was created, the behaviour is undefined."
 
 Issues
 
-    1. Should EGLSyncKHR objects that wrap Android fence objects use the
+    1. Should EGLSyncKHR objects that wrap native fence objects use the
     EGL_SYNC_FENCE_KHR type?
 
     RESOLVED: A new sync object type will be added.
 
-    We don't want to require all EGL fence sync objects to wrap Android fence
+    We don't want to require all EGL fence sync objects to wrap native fence
     objects, so we need some way to tell the EGL implementation at sync object
-    creation whether the sync object should support querying the Android fence
+    creation whether the sync object should support querying the native fence
     FD attribute. We could do this with either a new sync object type or with a
     boolean attribute. It might be nice to pick up future signaling conditions
     that might be added for fence sync objects, but there may be things that
-    get added that don't make sense in the context of Android fence objects.
+    get added that don't make sense in the context of native fence objects.
 
-    2. Who is responsible for dup'ing the Android fence file descriptors?
+    2. Who is responsible for dup'ing the native fence file descriptors?
 
     RESOLVED: Whenever a file descriptor is passed into or returned from an
     EGL call in this extension, ownership of that file descriptor is
     transfered. The recipient of the file descriptor must close it when it is
     no longer needed, and the provider of the file descriptor must dup it
-    before providing it if they require continued use of the native Android
-    fence.
+    before providing it if they require continued use of the native fence.
 
-    3. Can the EGL_SYNC_ANDROID_FENCE_FD_ANDROID attribute be queried?
+    3. Can the EGL_SYNC_NATIVE_FENCE_FD_ANDROID attribute be queried?
 
     RESOLVED: No.
 
@@ -250,15 +256,21 @@ Issues
 
     That said, the attribute is useful both as a way to pass an existing file
     descriptor to eglCreateSyncKHR and as a way to describe the subsequent
-    behavior of EGL Android fence sync objects, so it is left as an attribute
+    behavior of EGL native fence sync objects, so it is left as an attribute
     for which the value cannot be queried.
 
 Revision History
 
+#3 (Jamie Gennis, September 4, 2012)
+    - Reworded the extension to refer to "native fence" objects rather than
+    "Android fence" objects.
+    - Added a paragraph to the overview that describes assumptions about the
+    native fence sync objects.
+
 #2 (Jamie Gennis, July 23, 2012)
     - Changed the file descriptor ownership transferring behavior.
     - Added the eglDupAndroidFenceFDANDROID function.
-    - Removed EGL_SYNC_ANDROID_FENCE_FD_ANDROID from the table of gettable
+    - Removed EGL_SYNC_NATIVE_FENCE_FD_ANDROID from the table of gettable
     attributes.
     - Added language specifying that a native Android fence is created at the
     flush following the creation of an EGL Android fence sync object that is