[Mesa-dev] [PATCH v3 19/19] i965/gen6: Force ALL_SLICES_AT_EACH_LOD for separate stencil/hiz

Jordan Justen jordan.l.justen at intel.com
Fri Aug 1 00:53:49 PDT 2014

For gen6 we will use the ALL_SLICES_AT_EACH_LOD miptree layout for
separate stencil/hiz. This is needed because gen6 hiz and separate
stencil only support a single miplevel. When accessing the other LODs,
we will program a tile aligned offset for the bo.

PRM Volume 1, Part 1, 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>
Reviewed-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 924792b..3808662 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -359,6 +359,7 @@ 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)))) {
+      const bool force_all_slices_at_each_lod = brw->gen == 6;
       mt->stencil_mt = intel_miptree_create(brw,
@@ -370,7 +371,7 @@ intel_miptree_create_layout(struct brw_context *brw,
-                                            false);
+                                            force_all_slices_at_each_lod);
       if (!mt->stencil_mt) {
 	 return NULL;
@@ -1387,6 +1388,7 @@ intel_miptree_alloc_hiz(struct brw_context *brw,
 			struct intel_mipmap_tree *mt)
    assert(mt->hiz_mt == NULL);
+   const bool force_all_slices_at_each_lod = brw->gen == 6;
    mt->hiz_mt = intel_miptree_create(brw,
@@ -1398,7 +1400,7 @@ intel_miptree_alloc_hiz(struct brw_context *brw,
-                                     false);
+                                     force_all_slices_at_each_lod);
    if (!mt->hiz_mt)
       return false;

More information about the mesa-dev mailing list