st/oxr: Detect VK_LAYER_MND_enable_timeline_semaphore

And enable timeline semaphore support if it is found.

src/xrt/state_trackers/oxr/oxr_session_gfx_vk.c

@@ -8,23 +8,65 @@
  * @ingroup comp_client
  */
 
-#include <stdlib.h>
-
-
 #include "xrt/xrt_instance.h"
 #include "xrt/xrt_gfx_vk.h"
 
 #include "util/u_misc.h"
 #include "util/u_debug.h"
 
+#include "vk/vk_helpers.h"
+
 #include "oxr_objects.h"
 #include "oxr_logger.h"
 #include "oxr_two_call.h"
 #include "oxr_handle.h"
 
+
 DEBUG_GET_ONCE_BOOL_OPTION(force_timeline_semaphores, "OXR_DEBUG_FORCE_TIMELINE_SEMAPHORES", false)
 
 
+static bool
+check_for_layer_mnd_enable_timeline_semaphore(struct oxr_logger *log,
+                                              VkInstance instance,
+                                              VkPhysicalDevice physical_device)
+{
+	PFN_vkEnumerateDeviceLayerProperties func =
+	    (PFN_vkEnumerateDeviceLayerProperties)vkGetInstanceProcAddr(instance, "vkEnumerateDeviceLayerProperties");
+	uint32_t prop_count = 0;
+	VkResult ret = VK_SUCCESS;
+
+	ret = func(physical_device, &prop_count, NULL);
+	if (ret != VK_SUCCESS) {
+		oxr_log(log, "vkEnumerateDeviceLayerProperties: %s", vk_result_string(ret));
+		return false;
+	}
+
+	if (prop_count == 0) {
+		// No layers, nothing more to do.
+		return false;
+	}
+
+	VkLayerProperties *props = NULL;
+	props = U_TYPED_ARRAY_CALLOC(VkLayerProperties, prop_count);
+
+	ret = func(physical_device, &prop_count, props);
+	if (ret != VK_SUCCESS) {
+		oxr_log(log, "vkEnumerateDeviceLayerProperties: %s", vk_result_string(ret));
+		free(props);
+		return false;
+	}
+
+	for (uint32_t i = 0; i < prop_count; i++) {
+		if (strcmp(props[i].layerName, "VK_LAYER_MND_enable_timeline_semaphore") == 0) {
+			free(props);
+			return true;
+		}
+	}
+
+	free(props);
+	return false;
+}
+
 XrResult
 oxr_session_populate_vk(struct oxr_logger *log,
                         struct oxr_system *sys,
@@ -33,6 +75,12 @@ oxr_session_populate_vk(struct oxr_logger *log,
 {
 	bool timeline_semaphore_enabled = sess->sys->vk.timeline_semaphore_enabled;
 
+	if (!timeline_semaphore_enabled &&
+	    check_for_layer_mnd_enable_timeline_semaphore(log, next->instance, next->physicalDevice)) {
+		oxr_log(log, "Found VK_LAYER_MND_enable_timeline_semaphore and enabled them!");
+		timeline_semaphore_enabled = true;
+	}
+
 	if (!timeline_semaphore_enabled && debug_get_bool_option_force_timeline_semaphores()) {
 		oxr_log(log, "Forcing timeline semaphores on, your app better have enabled them!");
 		timeline_semaphore_enabled = true;