i965: Unify CC_STATE and BLEND_STATE atoms on Haswell as a workaround

Re-emitting 3DSTATE_CC_STATE_POINTERS after emitting
3DSTATE_BLEND_STATE_POINTERS fixes the shadow flickering in
SuperTuxCart and Tropico 6 which was seen only on Haswell.
The reason for this is unknown and fix was found empirically.

The closest mention in PRM is that it should improve performance.
From the HSW PRM, volume 2b, page 823 (3DSTATE_BLEND_STATE_POINTERS):
 "When the BLEND_STATE pointer changes but not the CC_STATE pointer,
  driver needs to force a CC_STATE pointer change to improve
  blend performance in pixel backend."

Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/1834
Fixes: eca4a654 ("i965: Disable dual source blending when shader doesn't support it on gen8+")
Cc: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

diff --git a/src/mesa/drivers/dri/i965/genX_state_upload.c b/src/mesa/drivers/dri/i965/genX_state_upload.c
index 629849def749515e8734f48e7d83519fd32ad5a4..01f9d198104945b403f22986de896c5b47dd36d1 100644 (file)
--- a/src/mesa/drivers/dri/i965/genX_state_upload.c
+++ b/src/mesa/drivers/dri/i965/genX_state_upload.c
@@ -3051,7 +3051,7 @@ genX(upload_blend_state)(struct brw_context *brw)
 #endif
 }
 
-static const struct brw_tracked_state genX(blend_state) = {
+UNUSED static const struct brw_tracked_state genX(blend_state) = {
    .dirty = {
       .mesa = _NEW_BUFFERS |
               _NEW_COLOR |
@@ -3412,7 +3412,7 @@ genX(upload_color_calc_state)(struct brw_context *brw)
 #endif
 }
 
-static const struct brw_tracked_state genX(color_calc_state) = {
+UNUSED static const struct brw_tracked_state genX(color_calc_state) = {
    .dirty = {
       .mesa = _NEW_COLOR |
               _NEW_STENCIL |
@@ -3430,6 +3430,35 @@ static const struct brw_tracked_state genX(color_calc_state) = {
 };
 
 
+/* ---------------------------------------------------------------------- */
+
+#if GEN_IS_HASWELL
+static void
+genX(upload_color_calc_and_blend_state)(struct brw_context *brw)
+{
+   genX(upload_blend_state)(brw);
+   genX(upload_color_calc_state)(brw);
+}
+
+/* On Haswell when BLEND_STATE is emitted CC_STATE should also be re-emitted,
+ * this workarounds the flickering shadows in several games.
+ */
+static const struct brw_tracked_state genX(cc_and_blend_state) = {
+   .dirty = {
+      .mesa = _NEW_BUFFERS |
+              _NEW_COLOR |
+              _NEW_STENCIL |
+              _NEW_MULTISAMPLE,
+      .brw = BRW_NEW_BATCH |
+             BRW_NEW_BLORP |
+             BRW_NEW_CC_STATE |
+             BRW_NEW_FS_PROG_DATA |
+             BRW_NEW_STATE_BASE_ADDRESS,
+   },
+   .emit = genX(upload_color_calc_and_blend_state),
+};
+#endif
+
 /* ---------------------------------------------------------------------- */
 
 #if GEN_GEN >= 7
@@ -5697,8 +5726,12 @@ genX(init_atoms)(struct brw_context *brw)
       &gen7_l3_state,
       &gen7_push_constant_space,
       &gen7_urb,
+#if GEN_IS_HASWELL
+      &genX(cc_and_blend_state),
+#else
       &genX(blend_state),              /* must do before cc unit */
       &genX(color_calc_state), /* must do before cc unit */
+#endif
       &genX(depth_stencil_state),      /* must do before cc unit */
 
       &brw_vs_image_surfaces, /* Before vs push/pull constants and binding table */