tu: Fix hangs for DS with no output
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5738>
diff --git a/src/freedreno/vulkan/tu_pipeline.c b/src/freedreno/vulkan/tu_pipeline.c
index 541d834..679e76f 100644
--- a/src/freedreno/vulkan/tu_pipeline.c
+++ b/src/freedreno/vulkan/tu_pipeline.c
@@ -847,6 +847,14 @@
tu6_setup_streamout(cs, last_shader, &linkage);
+ /* The GPU hangs on some models when there are no outputs (xs_pack::CNT),
+ * at least when a DS is the last stage, so add a dummy output to keep it
+ * happy if there aren't any. We do this late in order to avoid emitting
+ * any unused code and make sure that optimizations don't remove it.
+ */
+ if (linkage.cnt == 0)
+ ir3_link_add(&linkage, 0, 0x1, linkage.max_loc);
+
/* map outputs of the last shader to VPC */
assert(linkage.cnt <= 32);
const uint32_t sp_out_count = DIV_ROUND_UP(linkage.cnt, 2);
