From 7e45fc7dd9aade419938f0e64b879171728baaf4 Mon Sep 17 00:00:00 2001
From: Jakob Bornecrantz <jakob@collabora.com>
Date: Fri, 20 May 2022 11:13:58 +0100
Subject: [PATCH] t/common: Integrate null compositor

---
 CMakeLists.txt                           |  2 +-
 src/xrt/targets/common/CMakeLists.txt    | 11 +++++--
 src/xrt/targets/common/target_instance.c | 41 ++++++++++++++++++++++--
 3 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6e1a87c3a..38b9f7277 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -237,7 +237,7 @@ option(XRT_FEATURE_COLOR_LOG "Enable logging in color on supported platforms" ON
 option_with_deps(XRT_FEATURE_COMPOSITOR_MAIN "Build main compositor host functionality" DEPENDS XRT_HAVE_VULKAN "XRT_HAVE_WAYLAND OR XRT_HAVE_XCB OR ANDROID OR WIN32")
 option_with_deps(XRT_FEATURE_COMPOSITOR_NULL "Build testing null compositor" DEPENDS XRT_HAVE_VULKAN)
 option_with_deps(XRT_FEATURE_IPC "Enable the build of the IPC layer" DEPENDS "NOT WIN32")
-option_with_deps(XRT_FEATURE_OPENXR "Build OpenXR runtime target" DEPENDS XRT_FEATURE_COMPOSITOR_MAIN)
+option_with_deps(XRT_FEATURE_OPENXR "Build OpenXR runtime target" DEPENDS "XRT_FEATURE_COMPOSITOR_MAIN OR XRT_FEATURE_COMPOSITOR_NULL")
 option_with_deps(XRT_FEATURE_RENDERDOC "Enable RenderDoc API" DEPENDS "RT_LIBRARY OR WIN32")
 option_with_deps(XRT_FEATURE_SERVICE "Enable separate service module for OpenXR runtime" DEPENDS XRT_FEATURE_IPC XRT_FEATURE_OPENXR)
 option_with_deps(XRT_FEATURE_SERVICE_SYSTEMD "Enable systemd socket activation of the service" DEPENDS XRT_HAVE_SYSTEMD XRT_FEATURE_SERVICE)
diff --git a/src/xrt/targets/common/CMakeLists.txt b/src/xrt/targets/common/CMakeLists.txt
index d21ee6655..0341523dc 100644
--- a/src/xrt/targets/common/CMakeLists.txt
+++ b/src/xrt/targets/common/CMakeLists.txt
@@ -123,7 +123,7 @@ endif()
 ####
 # Instance
 #
-if(XRT_FEATURE_COMPOSITOR_MAIN)
+if(XRT_FEATURE_COMPOSITOR_MAIN OR XRT_FEATURE_COMPOSITOR_NULL)
 	add_library(target_instance STATIC target_instance.c)
 	target_link_libraries(
 		target_instance
@@ -132,10 +132,17 @@ if(XRT_FEATURE_COMPOSITOR_MAIN)
 			aux_util
 			st_prober
 			target_lists
-			comp_main
 			drv_includes
 		)
 	target_include_directories(target_instance PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+
+	if(XRT_FEATURE_COMPOSITOR_MAIN)
+		target_link_libraries(target_instance PRIVATE comp_main)
+	endif()
+
+	if(XRT_FEATURE_COMPOSITOR_NULL)
+		target_link_libraries(target_instance PRIVATE comp_null)
+	endif()
 endif()
 
 ####
diff --git a/src/xrt/targets/common/target_instance.c b/src/xrt/targets/common/target_instance.c
index d062d28c1..8fd013e94 100644
--- a/src/xrt/targets/common/target_instance.c
+++ b/src/xrt/targets/common/target_instance.c
@@ -1,4 +1,4 @@
-// Copyright 2020, Collabora, Ltd.
+// Copyright 2020-2022, Collabora, Ltd.
 // SPDX-License-Identifier: BSL-1.0
 /*!
  * @file
@@ -9,6 +9,7 @@
 #include "xrt/xrt_gfx_native.h"
 #include "xrt/xrt_system.h"
 
+#include "util/u_debug.h"
 #include "util/u_trace_marker.h"
 #include "util/u_system_helpers.h"
 
@@ -17,6 +18,19 @@
 #include <assert.h>
 
 
+#ifdef XRT_FEATURE_COMPOSITOR_MAIN
+#define USE_NULL_DEFAULT (false)
+#else
+#define USE_NULL_DEFAULT (true)
+#endif
+
+DEBUG_GET_ONCE_BOOL_OPTION(use_null, "XRT_COMPOSITOR_NULL", USE_NULL_DEFAULT)
+
+xrt_result_t
+null_compositor_create_system(struct xrt_device *xdev, struct xrt_system_compositor **out_xsysc);
+
+
+
 /*
  *
  * Internal functions.
@@ -49,7 +63,30 @@ t_instance_create_system(struct xrt_instance *xinst,
 
 	struct xrt_device *head = xsysd->roles.head;
 
-	xret = xrt_gfx_provider_create_system(head, &xsysc);
+	bool use_null = debug_get_bool_option_use_null();
+
+#ifdef XRT_FEATURE_COMPOSITOR_NULL
+	if (use_null) {
+		xret = null_compositor_create_system(head, &xsysc);
+	}
+#else
+	if (use_null) {
+		U_LOG_E("The null compositor is not compiled in!");
+		xret = XRT_ERROR_VULKAN;
+	}
+#endif
+
+#ifdef XRT_FEATURE_COMPOSITOR_MAIN
+	if (xret == XRT_SUCCESS && xsysc == NULL) {
+		xret = xrt_gfx_provider_create_system(head, &xsysc);
+	}
+#else
+	if (!use_null) {
+		U_LOG_E("Explicitly didn't request the null compositor, but the main compositor hasn't been built!");
+		xret = XRT_ERROR_VULKAN;
+	}
+#endif
+
 	if (xret != XRT_SUCCESS) {
 		xrt_system_devices_destroy(&xsysd);
 		return xret;