diff --git a/src/gallium/drivers/iris/iris_program.c b/src/gallium/drivers/iris/iris_program.c
index 105f4735555..635fd4ffdbe 100644
--- a/src/gallium/drivers/iris/iris_program.c
+++ b/src/gallium/drivers/iris/iris_program.c
@@ -1966,7 +1966,7 @@ iris_compile_fs(struct iris_screen *screen,
       .prog_data = fs_prog_data,
 
       .allow_spilling = true,
-      .max_polygons = 1,
+      .max_polygons = UCHAR_MAX,
       .vue_map = vue_map,
    };
 
diff --git a/src/gallium/drivers/iris/iris_state.c b/src/gallium/drivers/iris/iris_state.c
index 716d48e1678..85d50365346 100644
--- a/src/gallium/drivers/iris/iris_state.c
+++ b/src/gallium/drivers/iris/iris_state.c
@@ -7177,6 +7177,18 @@ iris_upload_dirty_render_state(struct iris_context *ice,
                                            wm_prog_data, util_framebuffer_get_num_samples(cso_fb),
                                            0 /* msaa_flags */);
 
+#if GFX_VER == 12
+               assert(wm_prog_data->dispatch_multi == 0 ||
+                      (wm_prog_data->dispatch_multi == 16 && wm_prog_data->max_polygons == 2));
+               ps.DualSIMD8DispatchEnable = wm_prog_data->dispatch_multi;
+               /* XXX - No major improvement observed from enabling
+                *       overlapping subspans, but it could be helpful
+                *       in theory when the requirements listed on the
+                *       BSpec page for 3DSTATE_PS_BODY are met.
+                */
+               ps.OverlappingSubspansEnable = false;
+#endif
+
                ps.DispatchGRFStartRegisterForConstantSetupData0 =
                   brw_wm_prog_data_dispatch_grf_start_reg(wm_prog_data, ps, 0);
                ps.DispatchGRFStartRegisterForConstantSetupData1 =