i965: Fix occlusion query on sandybridge

Clear target query buffer fixed occlusion query on sandybridge.

https://bugs.freedesktop.org/show_bug.cgi?id=32167

diff --git a/src/mesa/drivers/dri/i965/brw_queryobj.c b/src/mesa/drivers/dri/i965/brw_queryobj.c
index f28f28663ea728cce8ce33c2abfdf482ea1ed20f..656aad630a19024d84ef99a4b5197b986c6ea683 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_queryobj.c
+++ b/src/mesa/drivers/dri/i965/brw_queryobj.c
@@ -232,6 +232,12 @@ brw_prepare_query_begin(struct brw_context *brw)
       brw->query.bo = NULL;
 
       brw->query.bo = drm_intel_bo_alloc(intel->bufmgr, "query", 4096, 1);
+
+      /* clear target buffer */
+      drm_intel_bo_map(brw->query.bo, GL_TRUE);
+      memset((char *)brw->query.bo->virtual, 0, 4096);
+      drm_intel_bo_unmap(brw->query.bo);
+
       brw->query.index = 0;
    }