[Mesa-dev] [PATCH] i965: Move control flush into pipelined conditional render

[Chris Wilson]

The nv_conditional_render piglits were sporadically failing. Moving
the control flush from the write and placing it just before the read
was sufficient to make the piglits pass a 1000/1000 times. The bspec
says that the flush enable bit "waits until all previous writes of
immediate data from post sync circles are complete before executing the
next commend" - the operative word being previous!

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Neil Roberts <neil at linux.intel.com>
Cc: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_conditional_render.c |  6 ++++++
 src/mesa/drivers/dri/i965/brw_queryobj.c           | 19 +++++--------------
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_conditional_render.c b/src/mesa/drivers/dri/i965/brw_conditional_render.c
index 6d37c3b..122a4ec 100644
--- a/src/mesa/drivers/dri/i965/brw_conditional_render.c
+++ b/src/mesa/drivers/dri/i965/brw_conditional_render.c
@@ -56,6 +56,12 @@ set_predicate_for_result(struct brw_context *brw,
 
    assert(query->bo != NULL);
 
+   /* Needed to ensure the memory is coherent for the MI_LOAD_REGISTER_MEM
+    * command when loading the values into the predicate source registers for
+    * conditional rendering.
+    */
+   brw_emit_pipe_control_flush(brw, PIPE_CONTROL_FLUSH_ENABLE);
+
    brw_load_register_mem64(brw,
                            MI_PREDICATE_SRC0,
                            query->bo,
diff --git a/src/mesa/drivers/dri/i965/brw_queryobj.c b/src/mesa/drivers/dri/i965/brw_queryobj.c
index d6b012c..a8e5aba 100644
--- a/src/mesa/drivers/dri/i965/brw_queryobj.c
+++ b/src/mesa/drivers/dri/i965/brw_queryobj.c
@@ -66,20 +66,11 @@ brw_write_timestamp(struct brw_context *brw, drm_intel_bo *query_bo, int idx)
 void
 brw_write_depth_count(struct brw_context *brw, drm_intel_bo *query_bo, int idx)
 {
-   uint32_t flags;
-
-   flags = (PIPE_CONTROL_WRITE_DEPTH_COUNT |
-            PIPE_CONTROL_DEPTH_STALL);
-
-   /* Needed to ensure the memory is coherent for the MI_LOAD_REGISTER_MEM
-    * command when loading the values into the predicate source registers for
-    * conditional rendering.
-    */
-   if (brw->predicate.supported)
-      flags |= PIPE_CONTROL_FLUSH_ENABLE;
-
-   brw_emit_pipe_control_write(brw, flags, query_bo,
-                               idx * sizeof(uint64_t), 0, 0);
+   brw_emit_pipe_control_write(brw,
+                               PIPE_CONTROL_WRITE_DEPTH_COUNT |
+                               PIPE_CONTROL_DEPTH_STALL,
+                               query_bo, idx * sizeof(uint64_t),
+                               0, 0);
 }
 
 /**
-- 
2.5.0