[Mesa-dev] [PATCH 17/17] i965/gen6: Force non_mip_arrays for separate stencil/hiz

[Jordan Justen]

For gen6 we will use non-mipmapped array spacing, but with multiple
mip levels. This is needed because gen6 hiz and separate stencil only
support a single mip-level.

PRM Volume 1, Part 1, 7.18.3.7.2 For separate stencil buffer [DevILK]
to [DevSNB]:
 "The separate stencil buffer does not support mip mapping, thus the
  storage for LODs other than LOD 0 is not needed."

We still allocate storage for the other stencil mip-levels within a
single texture, but each mip-level will use non-mip-array spacing.

PRM Volume 2, Part 1, 7.5.3 Hierarchical Depth Buffer
 "[DevSNB]: The hierarchical depth buffer does not support the LOD
  field, it is assumed by hardware to be zero. A separate
  hierarachical depth buffer is required for each LOD used, and the
  corresponding buffer’s state delivered to hardware each time a new
  depth buffer state with modified LOD is delivered."

We allocate storage for the other hiz mip-levels within a single
texture, but each mip-level will use non-mip-array spacing.

Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
---
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 2a5afab..67cf515 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -331,8 +331,10 @@ intel_miptree_create_layout(struct brw_context *brw,
       }
    }
 
-   /* non_mip_arrays is only used for non-IMS MSAA surfaces.  TODO: can we
-    * use it elsewhere?
+   /* non_mip_arrays is only used for:
+    * - non-IMS MSAA surfaces
+    * - gen6 separate stencil
+    * - gen6 hiz
     */
    switch (mt->msaa_layout) {
    case INTEL_MSAA_LAYOUT_NONE:
@@ -358,6 +360,7 @@ intel_miptree_create_layout(struct brw_context *brw,
        _mesa_get_format_base_format(format) == GL_DEPTH_STENCIL &&
        (brw->must_use_separate_stencil ||
 	(brw->has_separate_stencil && brw_is_hiz_depth_format(brw, format)))) {
+      bool force_non_mip_arrays = brw->gen == 6;
       mt->stencil_mt = intel_miptree_create(brw,
                                             mt->target,
                                             MESA_FORMAT_S_UINT8,
@@ -369,7 +372,7 @@ intel_miptree_create_layout(struct brw_context *brw,
                                             true,
                                             num_samples,
                                             INTEL_MIPTREE_TILING_ANY,
-                                            false);
+                                            force_non_mip_arrays);
       if (!mt->stencil_mt) {
 	 intel_miptree_release(&mt);
 	 return NULL;
@@ -1386,6 +1389,7 @@ intel_miptree_alloc_hiz(struct brw_context *brw,
 			struct intel_mipmap_tree *mt)
 {
    assert(mt->hiz_mt == NULL);
+   bool force_non_mip_arrays = brw->gen == 6;
    mt->hiz_mt = intel_miptree_create(brw,
                                      mt->target,
                                      mt->format,
@@ -1397,7 +1401,7 @@ intel_miptree_alloc_hiz(struct brw_context *brw,
                                      true,
                                      mt->num_samples,
                                      INTEL_MIPTREE_TILING_ANY,
-                                     false);
+                                     force_non_mip_arrays);
 
    if (!mt->hiz_mt)
       return false;
-- 
2.0.1