libweston: Introduce zwp_linux_explicit_synchronization_v1

Introduce support for the zwp_linux_explicit_synchronization_unstable_v1
protocol with an implementation of the zwp_linux_explicit_synchronization_v1
interface.

Explicit synchronization provides a more versatile notification
mechanism for buffer readiness and availability, and can be used to
improve efficiency by integrating with related functionality in display
and graphics APIs.

In addition, the per-commit nature of the release events provided by
this protocol potentially offers a solution to a deficiency of the
wl_buffer.release event (see
https://gitlab.freedesktop.org/wayland/wayland/issues/46).

Support for this protocol depends on the capabilities of the backend, so
we don't register it by default but provide a function which each
backend will need to call. In this commit only the headless backend when
using the noop renderer supports this to enable testing.

Note that the zwp_surface_synchronization_v1 interface, which contains
the core functionality of the protocol, is not implemented in this
commit. Support for it will be added in future commits.

Changes in v7:
  - Added some information in the commit message about the benefits of
    the explicit sync protocol.

Changes in v6:
  - Fall back to advertising minor version 1 of the explicit sync protocol,
    although we support minor version 2 features, until the new
    wayland-protocols version is released.

Changes in v5:
  - Meson support.
  - Advertise minor version 2 of the explicit sync protocol.

Changes in v4:
  - Enable explicit sync support in the headless backend for all
    renderers.

Changes in v3:
  - Use wl_resource_get_version() instead of hardcoding version 1.
  - Use updated protocol interface names.
  - Use correct format specifier for resource id.
  - Change test name to 'linux-explicit-synchronization.weston'
    (s/_/-/g).

Changes in v2:
  - Move implementation to separate file so protocol can be registered
    on demand by backends.
  - Register protocol in headless+noop backend for testing purposes.

Signed-off-by: Alexandros Frantzis <alexandros.frantzis@collabora.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/Makefile.am b/Makefile.am
index 24561a58..358dd7bb 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -94,6 +94,8 @@ libweston_@LIBWESTON_MAJOR@_la_SOURCES =			\
 	libweston/timeline-object.h			\
 	libweston/linux-dmabuf.c			\
 	libweston/linux-dmabuf.h			\
+	libweston/linux-explicit-synchronization.c	\
+	libweston/linux-explicit-synchronization.h	\
 	libweston/pixel-formats.c			\
 	libweston/pixel-formats.h			\
 	libweston/weston-debug.c			\
@@ -177,7 +179,9 @@ nodist_libweston_@LIBWESTON_MAJOR@_la_SOURCES =				\
 	protocol/input-timestamps-unstable-v1-protocol.c		\
 	protocol/input-timestamps-unstable-v1-server-protocol.h		\
 	protocol/weston-touch-calibration-protocol.c			\
-	protocol/weston-touch-calibration-server-protocol.h
+	protocol/weston-touch-calibration-server-protocol.h		\
+	protocol/linux-explicit-synchronization-unstable-v1-protocol.c	\
+	protocol/linux-explicit-synchronization-unstable-v1-server-protocol.h
 
 BUILT_SOURCES += $(nodist_libweston_@LIBWESTON_MAJOR@_la_SOURCES)
 
@@ -968,7 +972,9 @@ BUILT_SOURCES +=					\
 	protocol/input-timestamps-unstable-v1-protocol.c		\
 	protocol/input-timestamps-unstable-v1-client-protocol.h		\
 	protocol/xdg-output-unstable-v1-protocol.c			\
-	protocol/xdg-output-unstable-v1-client-protocol.h
+	protocol/xdg-output-unstable-v1-client-protocol.h		\
+	protocol/linux-explicit-synchronization-unstable-v1-protocol.c	\
+	protocol/linux-explicit-synchronization-unstable-v1-client-protocol.h
 
 westondatadir = $(datadir)/weston
 dist_westondata_DATA =				\
@@ -1308,7 +1314,8 @@ weston_tests =					\
 	subsurface.weston			\
 	subsurface-shot.weston			\
 	devices.weston				\
-	touch.weston
+	touch.weston				\
+	linux-explicit-synchronization.weston
 
 AM_TESTS_ENVIRONMENT = \
 	abs_builddir='$(abs_builddir)'; export abs_builddir; \
@@ -1502,6 +1509,14 @@ touch_weston_SOURCES = tests/touch-test.c
 touch_weston_CFLAGS = $(AM_CFLAGS) $(TEST_CLIENT_CFLAGS)
 touch_weston_LDADD = libtest-client.la
 
+linux_explicit_synchronization_weston_SOURCES = \
+	tests/linux-explicit-synchronization-test.c
+nodist_linux_explicit_synchronization_weston_SOURCES = \
+	protocol/linux-explicit-synchronization-unstable-v1-protocol.c	\
+	protocol/linux-explicit-synchronization-unstable-v1-client-protocol.h
+linux_explicit_synchronization_weston_CFLAGS = $(AM_CFLAGS) $(TEST_CLIENT_CFLAGS)
+linux_explicit_synchronization_weston_LDADD = libtest-client.la
+
 if ENABLE_XWAYLAND_TEST
 weston_tests +=	xwayland-test.weston
 xwayland_test_weston_SOURCES = tests/xwayland-test.c