[Mesa-dev] [PATCH 04/14] i965/gen7: Don't allocate hiz miptree structure

[Pohjolainen, Topi]

On Fri, Jul 18, 2014 at 11:02:56AM +0300, Pohjolainen, Topi wrote:
> On Tue, Jul 15, 2014 at 06:32:12PM -0700, Jordan Justen wrote:
> > We now skip allocating a hiz miptree for gen7. Instead, we calculate
> > the required hiz buffer parameters and allocate a bo directly.
> > 
> > Signed-off-by: Jordan Justen <jordan.l.justen at intel.com>
> > ---
> >  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 95 ++++++++++++++++++++++++++-
> >  1 file changed, 93 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 8719c29..7e8bec8 100644
> > --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > @@ -823,7 +823,10 @@ intel_miptree_release(struct intel_mipmap_tree **mt)
> >        drm_intel_bo_unreference((*mt)->bo);
> >        intel_miptree_release(&(*mt)->stencil_mt);
> >        if ((*mt)->hiz_buf) {
> > -         intel_miptree_release(&(*mt)->hiz_buf->mt);
> > +         if ((*mt)->hiz_buf->mt)
> > +            intel_miptree_release(&(*mt)->hiz_buf->mt);
> > +         else
> > +            drm_intel_bo_unreference((*mt)->hiz_buf->bo);
> >           free((*mt)->hiz_buf);
> >        }
> >        intel_miptree_release(&(*mt)->mcs_mt);
> > @@ -1374,6 +1377,89 @@ intel_miptree_level_enable_hiz(struct brw_context *brw,
> >  }
> >  
> >  
> > +/**
> > + * Helper for intel_miptree_alloc_hiz() that determines the required hiz
> > + * buffer dimensions and allocates a bo for the hiz buffer.
> > + */
> > +static struct intel_miptree_aux_buffer *
> > +intel_gen7_hiz_buf_create(struct brw_context *brw,
> > +                          struct intel_mipmap_tree *mt)
> > +{
> > +   unsigned z_width = mt->logical_width0;
> > +   unsigned z_height = mt->logical_height0;
> > +   const unsigned z_depth = mt->logical_depth0;
> > +   unsigned hz_width, hz_height, qpitch;
> > +   struct intel_miptree_aux_buffer *buf = calloc(sizeof(*buf), 1);
> > +
> > +   if (!buf)
> > +      return NULL;
> > +
> > +   /* Gen7 PRM Volume 2, Part 1, 11.5.3 "Hierarchical Depth Buffer" documents
> > +    * adjustments required for Z_Height and Z_Width based on multisampling.
> > +    */
> > +   switch(mt->num_samples) {
> > +   case 0:
> > +   case 1:
> > +      break;
> > +   case 2:
> > +   case 4:
> > +      z_width *= 2;
> > +      z_height *= 2;
> > +      break;
> > +   case 8:
> > +      z_width *= 4;
> > +      z_height *= 2;
> > +      break;
> > +   default:
> > +      assert(!"Unsupported sample count!");
> > +   }
> > +
> > +   const unsigned vertical_align = 8; /* 'j' in the docs */
> > +   const unsigned H0 = z_height;
> > +   const unsigned h0 = ALIGN(H0, vertical_align);
> > +   const unsigned h1 = ALIGN(minify(H0, 1), vertical_align);
> > +   const unsigned Z0 = z_depth;
> > +
> > +   /* HZ_Width (bytes) = ceiling(Z_Width / 16) * 16 */
> > +   hz_width = ALIGN(z_width, 16);
> > +
> > +   if (mt->target == GL_TEXTURE_3D) {
> > +      unsigned H_i = H0;
> > +      unsigned Z_i = Z0;
> > +      hz_height = 0;
> > +      for (int level = mt->first_level; level <= mt->last_level; ++level) {
> > +         unsigned h_i = ALIGN(H_i, vertical_align);
> > +         /* sum(i=0 to m; h_i * max(1, floor(Z_Depth/2**i))) */
> > +         hz_height += h_i * Z_i;
> > +         H_i = minify(H_i, 1);
> > +         Z_i = minify(Z_i, 1);
> > +      }
> > +      /* HZ_Height =
> > +       *    (1/2) * sum(i=0 to m; h_i * max(1, floor(Z_Depth/2**i)))
> > +       */
> > +      hz_height = CEILING(hz_height, 2);
> > +   } else {
> > +      qpitch = h0 + h1 + (12 * vertical_align);
> 
> I wonder if we are reading the same spec. I'm still in the opinion that this
> is the formula for the normal (non-hiz) miptrees. In the table in section
> 3D-Media-GPGPU Engine > 3D Pipeline Stages > Pixel >
> Early Depth/Stencil Processing > Hierarchical Depth Buffer there is a special
> iterative formula for 1D/2D hiz just as there is special case for 3D hiz.
> 
> For 1D/2D: HZ_QPitch = h_0 + max(h1, sum(i=2 to m: h_i))

Oh, you had this in the next patch for gen8. Sorry, my mistake, I should have
checked the specs for the older hw.

> 
> > +      /* HZ_Height (rows) = Ceiling ( ( Q_pitch * Z_depth/2) /8 ) * 8 */
> > +      hz_height = (ALIGN(qpitch, 8) / 2) * Z0;
> > +      if (mt->target == GL_TEXTURE_CUBE_MAP_ARRAY ||
> > +          mt->target == GL_TEXTURE_CUBE_MAP) {
> > +         hz_height *= 6;
> > +      }
> > +   }
> > +
> > +   unsigned long pitch;
> > +   uint32_t tiling = I915_TILING_Y;
> > +   buf->bo = drm_intel_bo_alloc_tiled(brw->bufmgr, "hiz",
> > +                                      hz_width, hz_height, 1,
> > +                                      &tiling, &pitch,
> > +                                      BO_ALLOC_FOR_RENDER);
> > +   buf->pitch = pitch;
> > +
> > +   return buf;
> > +}
> > +
> > +
> >  static struct intel_miptree_aux_buffer *
> >  intel_hiz_miptree_buf_create(struct brw_context *brw,
> >                               struct intel_mipmap_tree *mt)
> > @@ -1412,7 +1498,12 @@ intel_miptree_alloc_hiz(struct brw_context *brw,
> >  			struct intel_mipmap_tree *mt)
> >  {
> >     assert(mt->hiz_buf == NULL);
> > -   mt->hiz_buf = intel_hiz_miptree_buf_create(brw, mt);
> > +
> > +   if (brw->gen == 7) {
> > +      mt->hiz_buf = intel_gen7_hiz_buf_create(brw, mt);
> > +   } else {
> > +      mt->hiz_buf = intel_hiz_miptree_buf_create(brw, mt);
> > +   }
> >  
> >     if (!mt->hiz_buf)
> >        return false;
> > -- 
> > 2.0.0
> > 
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