intel: Export a function to re-enable implicit synchronisation

Implicit synchronisation is the default behaviour of the kernel when
rendering with an execobject. It may be disabled with
drm_intel_gem_bo_disable_implicit_sync(), and then to restore it use
drm_intel_gem_bo_enable_implicit_sync().

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

2 files changed, 20 insertions, 0 deletions

diff --git a/intel/intel_bufmgr.h b/intel/intel_bufmgr.h
index 11579fbc..693472a5 100644
--- a/intel/intel_bufmgr.h
+++ b/intel/intel_bufmgr.h
@@ -187,6 +187,7 @@ int drm_intel_gem_bo_unmap_gtt(drm_intel_bo *bo);
 #define HAVE_DRM_INTEL_GEM_BO_DISABLE_IMPLICIT_SYNC 1
 int drm_intel_bufmgr_gem_can_disable_implicit_sync(drm_intel_bufmgr *bufmgr);
 void drm_intel_gem_bo_disable_implicit_sync(drm_intel_bo *bo);
+void drm_intel_gem_bo_enable_implicit_sync(drm_intel_bo *bo);
 
 void *drm_intel_gem_bo_map__cpu(drm_intel_bo *bo);
 void *drm_intel_gem_bo_map__gtt(drm_intel_bo *bo);
diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
index 077746cd..a6656003 100644
--- a/intel/intel_bufmgr_gem.c
+++ b/intel/intel_bufmgr_gem.c
@@ -2816,6 +2816,25 @@ drm_intel_gem_bo_disable_implicit_sync(drm_intel_bo *bo)
 }
 
 /**
+ * Enables implicit synchronisation before executing the bo
+ *
+ * This is the default behaviour of the kernel, to wait upon prior writes
+ * completing on the object before rendering with it, or to wait for prior
+ * reads to complete before writing into the object.
+ * drm_intel_gem_bo_disable_implicit_sync() can stop this behaviour, telling
+ * the kernel never to insert a stall before using the object. Then this
+ * function can be used to restore the implicit sync before subsequent
+ * rendering.
+ */
+void
+drm_intel_gem_bo_enable_implicit_sync(drm_intel_bo *bo)
+{
+	drm_intel_bo_gem *bo_gem = (drm_intel_bo_gem *) bo;
+
+	bo_gem->kflags &= ~EXEC_OBJECT_ASYNC;
+}
+
+/**
  * Query whether the kernel supports disabling of its implicit synchronisation
  * before execbuf. See drm_intel_gem_bo_disable_implicit_sync()
  */