Currently we signal the availabilty of the query result using an
unordered pipe-control write. As it is unordered, it may be executed
before the write of the query result itself - and so an observer may
read the query result too early. Fix this by requesting that the write
of the availablity flag is ordered after earlier pipe control writes.
Testcase: piglit/arb_query_buffer_object-qbo/*async*
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
---
src/mesa/drivers/dri/i965/gen6_queryobj.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/gen6_queryobj.c
b/src/mesa/drivers/dri/i965/gen6_queryobj.c
index bbd3c44..f6b90f7 100644
--- a/src/mesa/drivers/dri/i965/gen6_queryobj.c
+++ b/src/mesa/drivers/dri/i965/gen6_queryobj.c
@@ -60,8 +60,16 @@ set_query_availability(struct brw_context *brw, struct
brw_query_object *query,
*/
if (brw->ctx.Extensions.ARB_query_buffer_object &&
brw_is_query_pipelined(query)) {
- brw_emit_pipe_control_write(brw,
- PIPE_CONTROL_WRITE_IMMEDIATE,
+ unsigned flags = PIPE_CONTROL_WRITE_IMMEDIATE;
+
+ if (available)
+ /* Order available *after* the query results */
+ flags |= PIPE_CONTROL_FLUSH_ENABLE;
+ else
+ /* Make it unavailable *before* any pipelined reads */
+ flags |= PIPE_CONTROL_CS_STALL;
+
+ brw_emit_pipe_control_write(brw, flags,
query->bo, 2 * sizeof(uint64_t),
available, 0);
}
--
2.10.2
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