i965: Emit a dummy MEDIA_VFE_STATE before switching from GPGPU to 3D

There is an object-level  preemption workaround which requires this.
However, even without object-level preemption, we seem to have issues
with geometry flickering when 3D and compute are combined in the same
batch and this appears to fix it.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=110395
Suggested-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Cc: mesa-stable@lists.freedesktop.org

diff --git a/src/mesa/drivers/dri/i965/brw_misc_state.c b/src/mesa/drivers/dri/i965/brw_misc_state.c
index b752294250e3effc4d6b3e33c9c404fe9f1584e8..e73cadc5d3e6f8a8cfd99c9b456dbcefa016898e 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_misc_state.c
+++ b/src/mesa/drivers/dri/i965/brw_misc_state.c
@@ -493,6 +493,27 @@ brw_emit_select_pipeline(struct brw_context *brw, enum brw_pipeline pipeline)
       }
    }
 
+   if (devinfo->gen == 9 && pipeline == BRW_RENDER_PIPELINE) {
+      /* We seem to have issues with geometry flickering when 3D and compute
+       * are combined in the same batch and this appears to fix it.
+       */
+      const uint32_t subslices = MAX2(brw->screen->subslice_total, 1);
+      const uint32_t maxNumberofThreads =
+         devinfo->max_cs_threads * subslices - 1;
+
+      BEGIN_BATCH(9);
+      OUT_BATCH(MEDIA_VFE_STATE << 16 | (9 - 2));
+      OUT_BATCH(0);
+      OUT_BATCH(0);
+      OUT_BATCH(2 << 8 | maxNumberofThreads << 16);
+      OUT_BATCH(0);
+      OUT_BATCH(2 << 16);
+      OUT_BATCH(0);
+      OUT_BATCH(0);
+      OUT_BATCH(0);
+      ADVANCE_BATCH();
+   }
+
    if (devinfo->gen >= 6) {
       /* From "BXML » GT » MI » vol1a GPU Overview » [Instruction]
        * PIPELINE_SELECT [DevBWR+]":