src/panfrost/midgard/midgard_errata_lod.c

   1 /*
   2  * Copyright (C) 2019 Collabora, Ltd.
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 #include "compiler/nir/nir.h"
  25 #include "compiler/nir/nir_builder.h"
  26
  27 void midgard_nir_lod_errata(nir_shader *shader);
  28
  29 /* Workarounds errata pertaining to early Midgard chips where the settings for
  30  * min_lod/max_lod/lod_bias are ignored in the sampler descriptor when
  31  * texturing with a textureLod instruction. The workaround is to load these
  32  * constants in as system values and perform the bias/clamp in the shader.
  33  */
  34
  35 static void
  36 mir_lod_errata_body(nir_builder *b, nir_tex_instr *tex)
  37 {
  38         /* The errata only applies to textureLod ("TEXGRD") */
  39         if (tex->op != nir_texop_txl)
  40                 return;
  41
  42         /* Let's grab the sampler parameters */
  43         nir_intrinsic_instr *l = nir_intrinsic_instr_create(b->shader,
  44                         nir_intrinsic_load_sampler_lod_parameters_pan);
  45         l->num_components = 3;
  46         nir_ssa_dest_init(&l->instr, &l->dest, 3, 32, NULL);
  47
  48         /* TODO: Indirect samplers, separate sampler objects XXX */
  49         nir_src idx = nir_src_for_ssa(nir_imm_int(b, tex->texture_index));
  50         nir_src_copy(&l->src[0], &idx, l);
  51
  52         nir_builder_instr_insert(b, &l->instr);
  53         nir_ssa_def *params = &l->dest.ssa;
  54
  55         /* Extract the individual components */
  56         nir_ssa_def *min_lod = nir_channel(b, params, 0);
  57         nir_ssa_def *max_lod = nir_channel(b, params, 1);
  58         nir_ssa_def *lod_bias = nir_channel(b, params, 2);
  59
  60         /* Rewrite the LOD with bias/clamps. Order sensitive. */
  61         for (unsigned i = 0; i < tex->num_srcs; i++) {
  62                 if (tex->src[i].src_type != nir_tex_src_lod)
  63                         continue;
  64
  65                 nir_ssa_def *lod = nir_ssa_for_src(b, tex->src[i].src, 1);
  66
  67                 nir_ssa_def *biased = nir_fadd(b, lod, lod_bias);
  68                 nir_ssa_def *clamped = nir_fmin(b,
  69                                 nir_fmax(b, biased, min_lod), max_lod);
  70
  71                 nir_instr_rewrite_src(&tex->instr, &tex->src[i].src,
  72                                 nir_src_for_ssa(clamped));
  73         }
  74 }
  75
  76 void
  77 midgard_nir_lod_errata(nir_shader *shader)
  78 {
  79         nir_foreach_function(function, shader) {
  80                 if (!function->impl) continue;
  81
  82                 nir_builder b;
  83                 nir_builder_init(&b, function->impl);
  84
  85                 nir_foreach_block(block, function->impl) {
  86                         nir_foreach_instr_safe(instr, block) {
  87                                 if (instr->type != nir_instr_type_tex) continue;
  88
  89                                 nir_tex_instr *tex = nir_instr_as_tex(instr);
  90                                 b.cursor = nir_before_instr(instr);
  91                                 mir_lod_errata_body(&b, tex);
  92                         }
  93                 }
  94
  95                 nir_metadata_preserve(function->impl, nir_metadata_block_index | nir_metadata_dominance);
  96
  97         }
  98 }