[Mesa-dev] [PATCH 3/3] i965/miptree: Stop retiling miptrees

[Nanley Chery]

We previously retiled miptrees to work around limitations of the BLT
engine. BLORP fallbacks can overcome these, so we no longer have need
for retiling.

Removing retiling fixes a number of problems. If the row pitch was too
wide for the BLT engine, we retiled to linear and had the following
issues:
* We retiled on gen6+ platforms which don't actually use the blitter.
* We ignored miptree_create_for_bo's requests for tiled miptrees.

I don't know how to write a test for the last issue unfortunately. Also,
I haven't nominated this for stable releases, because of the amount of
churn needed - we'd have to pull in the series which stops using the
blitter on gen6+.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106738
---
 src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 62 +------------------
 1 file changed, 1 insertion(+), 61 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
index 1c888d5210b..a57720b338a 100644
--- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
+++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
@@ -509,46 +509,6 @@ free_aux_state_map(enum isl_aux_state **state)
    free(state);
 }
 
-static bool
-need_to_retile_as_linear(struct brw_context *brw, unsigned row_pitch,
-                         enum isl_tiling tiling, unsigned samples)
-{
-   if (samples > 1)
-      return false;
-
-   if (tiling == ISL_TILING_LINEAR)
-      return false;
-
-    /* If the width is much smaller than a tile, don't bother tiling. */
-   if (row_pitch < 64)
-      return true;
-
-   if (ALIGN(row_pitch, 512) >= 32768) {
-      perf_debug("row pitch %u too large to blit, falling back to untiled",
-                 row_pitch);
-      return true;
-   }
-
-   return false;
-}
-
-static bool
-need_to_retile_as_x(const struct brw_context *brw, uint64_t size,
-                    enum isl_tiling tiling)
-{
-   const struct gen_device_info *devinfo = &brw->screen->devinfo;
-
-   /* If the BO is too large to fit in the aperture, we need to use the
-    * BLT engine to support it.  Prior to Sandybridge, the BLT paths can't
-    * handle Y-tiling, so we need to fall back to X.
-    */
-   if (devinfo->gen < 6 && size >= brw->max_gtt_map_object_size &&
-       tiling == ISL_TILING_Y0)
-      return true;
-
-   return false;
-}
-
 static struct intel_mipmap_tree *
 make_surface(struct brw_context *brw, GLenum target, mesa_format format,
              unsigned first_level, unsigned last_level,
@@ -580,7 +540,7 @@ make_surface(struct brw_context *brw, GLenum target, mesa_format format,
        num_samples, width0, height0, depth0,
        first_level, last_level, mt);
 
-   struct isl_surf_init_info init_info = {
+   const struct isl_surf_init_info init_info = {
       .dim = get_isl_surf_dim(target),
       .format = translate_tex_format(brw, format, false),
       .width = width0,
@@ -597,26 +557,6 @@ make_surface(struct brw_context *brw, GLenum target, mesa_format format,
    if (!isl_surf_init_s(&brw->isl_dev, &mt->surf, &init_info))
       goto fail;
 
-   /* Depth surfaces are always Y-tiled and stencil is always W-tiled, although
-    * on gen7 platforms we also need to create Y-tiled copies of stencil for
-    * texturing since the hardware can't sample from W-tiled surfaces. For
-    * everything else, check for corner cases needing special treatment.
-    */
-   bool is_depth_stencil =
-      mt->surf.usage & (ISL_SURF_USAGE_STENCIL_BIT | ISL_SURF_USAGE_DEPTH_BIT);
-   if (!is_depth_stencil) {
-      if (need_to_retile_as_linear(brw, mt->surf.row_pitch,
-                                   mt->surf.tiling, mt->surf.samples)) {
-         init_info.tiling_flags = 1u << ISL_TILING_LINEAR;
-         if (!isl_surf_init_s(&brw->isl_dev, &mt->surf, &init_info))
-            goto fail;
-      } else if (need_to_retile_as_x(brw, mt->surf.size, mt->surf.tiling)) {
-         init_info.tiling_flags = 1u << ISL_TILING_X;
-         if (!isl_surf_init_s(&brw->isl_dev, &mt->surf, &init_info))
-            goto fail;
-      }
-   }
-
    /* In case of linear the buffer gets padded by fixed 64 bytes and therefore
     * the size may not be multiple of row_pitch.
     * See isl_apply_surface_padding().
-- 
2.17.0