[Mesa-dev] [PATCH 3/9] i965: Weaken the flushing in gen7_end_transform_feedback().

Kenneth Graunke kenneth at whitecape.org
Fri Oct 18 08:09:31 CEST 2013

Since 062317d6671 (i965: Go back to using the kernel SOL reset feature.)
we've been flushing the batch on BeginTransformFeedback().  So it's not
necessary to do it on EndTransformFeedback().  A PIPE_CONTROL will work.

This makes gen7_end_transform_feedback() exactly the same as the gen6
variant.  However, they'll diverge again shortly.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
 src/mesa/drivers/dri/i965/gen7_sol_state.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/gen7_sol_state.c b/src/mesa/drivers/dri/i965/gen7_sol_state.c
index fc69bfc..504d9e7 100644
--- a/src/mesa/drivers/dri/i965/gen7_sol_state.c
+++ b/src/mesa/drivers/dri/i965/gen7_sol_state.c
@@ -263,13 +263,13 @@ void
 gen7_end_transform_feedback(struct gl_context *ctx,
 			    struct gl_transform_feedback_object *obj)
-   /* Because we have to rely on the kernel to reset our SO write offsets, and
-    * we only get to do it once per batchbuffer, flush the batch after feedback
-    * so another transform feedback can get the write offset reset it needs.
-    *
-    * This also covers any cache flushing required.
+   /* After EndTransformFeedback, it's likely that the client program will try
+    * to draw using the contents of the transform feedback buffer as vertex
+    * input.  In order for this to work, we need to flush the data through at
+    * least the GS stage of the pipeline, and flush out the render cache.  For
+    * simplicity, just do a full flush.
    struct brw_context *brw = brw_context(ctx);
-   intel_batchbuffer_flush(brw);
+   intel_batchbuffer_emit_mi_flush(brw);

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