sna/gen6: Tweak flush around CC state changes

In order to fix some font corruption, it appears that we need an extra
flush in the Sandybridge pipeline when we change the CC stage and the
render cache is dirty. We previously triggered a full pipeline stall
for this case.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/src/sna/gen6_render.c b/src/sna/gen6_render.c
index f271cf8..9797ef9 100644 (file)
--- a/src/sna/gen6_render.c
+++ b/src/sna/gen6_render.c
@@ -866,21 +866,22 @@ gen6_emit_state(struct sna *sna,
                const struct sna_composite_op *op,
                uint16_t wm_binding_table)
 {
-       bool need_stall = wm_binding_table & 1;
+       bool need_flush, need_stall;
 
        assert(op->dst.bo->exec);
 
-       if (gen6_emit_cc(sna, GEN6_BLEND(op->u.gen6.flags)))
-               need_stall = false;
+       need_flush =
+               gen6_emit_cc(sna, GEN6_BLEND(op->u.gen6.flags)) &&
+               wm_binding_table & 1;
        gen6_emit_sampler(sna, GEN6_SAMPLER(op->u.gen6.flags));
        gen6_emit_sf(sna, GEN6_VERTEX(op->u.gen6.flags) >> 2);
        gen6_emit_wm(sna, GEN6_KERNEL(op->u.gen6.flags), GEN6_VERTEX(op->u.gen6.flags) >> 2);
        gen6_emit_vertex_elements(sna, op);
 
-       need_stall |= gen6_emit_binding_table(sna, wm_binding_table & ~1);
+       need_stall = gen6_emit_binding_table(sna, wm_binding_table & ~1);
        if (gen6_emit_drawing_rectangle(sna, op))
                need_stall = false;
-       if (kgem_bo_is_dirty(op->src.bo) || kgem_bo_is_dirty(op->mask.bo)) {
+       if (need_flush || kgem_bo_is_dirty(op->src.bo) || kgem_bo_is_dirty(op->mask.bo)) {
                gen6_emit_flush(sna);
                kgem_clear_dirty(&sna->kgem);
                assert(op->dst.bo->exec);