[Mesa-dev] [PATCH 4/6] i965/gen4-5: Emit MI_FLUSH as required prior to switching pipelines.
Francisco Jerez
currojerez at riseup.net
Sat Jan 2 22:48:03 PST 2016
AFAIK brw_emit_select_pipeline() is only called once during context
init on Gen4-5, at which point the pipeline is likely to be already
idle so it may just happen to work by luck regardless of the MI_FLUSH.
---
src/mesa/drivers/dri/i965/brw_misc_state.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/src/mesa/drivers/dri/i965/brw_misc_state.c b/src/mesa/drivers/dri/i965/brw_misc_state.c
index 75540c1..e5af1da 100644
--- a/src/mesa/drivers/dri/i965/brw_misc_state.c
+++ b/src/mesa/drivers/dri/i965/brw_misc_state.c
@@ -914,6 +914,19 @@ brw_emit_select_pipeline(struct brw_context *brw, enum brw_pipeline pipeline)
PIPE_CONTROL_STATE_CACHE_INVALIDATE |
PIPE_CONTROL_INSTRUCTION_INVALIDATE |
PIPE_CONTROL_NO_WRITE);
+
+ } else {
+ /* From "BXML » GT » MI » vol1a GPU Overview » [Instruction]
+ * PIPELINE_SELECT [DevBWR+]":
+ *
+ * Project: PRE-DEVSNB
+ *
+ * Software must ensure the current pipeline is flushed via an
+ * MI_FLUSH or PIPE_CONTROL prior to the execution of PIPELINE_SELECT.
+ */
+ BEGIN_BATCH(1);
+ OUT_BATCH(MI_FLUSH);
+ ADVANCE_BATCH();
}
/* Select the pipeline */
--
2.6.4
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