EGL_ANDROID_fence_sync: make it more generic (a1d49ce1) · Commits · e / os / android_frameworks_native

opengl/specs/EGL_ANDROID_fence_sync.txt→opengl/specs/EGL_ANDROID_native_fence_sync.txt

+73 −61

Original line number	Diff line number	Diff line
		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