pan/mdg: quirk to disable auto32

For some reason, flat shading on T604 does not work when using auto32 varyings
type.

This commit introduces a quirk for T60x, and some plumbing in pan_nir, allowing to
explicitely use appropriate types, rather than always using .u32 for flat shading.

Backport-to: 24.1
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/10632
Signed-off-by: Alexandre Marquet <tb@a-marquet.fr>
Reviewed-by: Eric R. Smith <eric.smith@collabora.com>
Acked-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28146>

src/panfrost/midgard/midgard_compile.c

@@ -1266,12 +1266,32 @@ emit_varying_read(compiler_context *ctx, unsigned dest, unsigned offset,
    ins.load_store.arg_reg = REGISTER_LDST_ZERO;
    ins.load_store.index_format = midgard_index_address_u32;
 
-   /* For flat shading, we always use .u32 and require 32-bit mode. For
-    * smooth shading, we use the appropriate floating-point type.
+   /* For flat shading, for GPUs supporting auto32, we always use .u32 and
+    * require 32-bit mode. For smooth shading, we use the appropriate
+    * floating-point type.
     *
     * This could be optimized, but it makes it easy to check correctness.
     */
-   if (flat) {
+   if (ctx->quirks & MIDGARD_NO_AUTO32) {
+      switch (type) {
+      case nir_type_uint32:
+      case nir_type_bool32:
+         ins.op = midgard_op_ld_vary_32u;
+         break;
+      case nir_type_int32:
+         ins.op = midgard_op_ld_vary_32i;
+         break;
+      case nir_type_float32:
+         ins.op = midgard_op_ld_vary_32;
+         break;
+      case nir_type_float16:
+         ins.op = midgard_op_ld_vary_16;
+         break;
+      default:
+         unreachable("Attempted to load unknown type");
+         break;
+      }
+   } else if (flat) {
       assert(nir_alu_type_get_type_size(type) == 32);
       ins.op = midgard_op_ld_vary_32u;
    } else {
@@ -2891,6 +2911,7 @@ midgard_compile_shader_nir(nir_shader *nir,
    ctx->ssa_constants = _mesa_hash_table_u64_create(ctx);
 
    /* Collect varyings after lowering I/O */
+   info->quirk_no_auto32 = (ctx->quirks & MIDGARD_NO_AUTO32);
    pan_nir_collect_varyings(nir, info);
 
    /* Optimisation passes */

src/panfrost/midgard/midgard_quirks.h

@@ -66,11 +66,19 @@
 
 #define MIDGARD_NO_OOO (1 << 5)
 
+/* Disable auto32 type (apparently broken on T60x). */
+
+#define MIDGARD_NO_AUTO32 (1 << 6)
+
 static inline unsigned
 midgard_get_quirks(unsigned gpu_id)
 {
    switch (gpu_id) {
    case 0x600:
+      return MIDGARD_OLD_BLEND | MIDGARD_BROKEN_BLEND_LOADS |
+             MIDGARD_BROKEN_LOD | MIDGARD_NO_UPPER_ALU | MIDGARD_NO_OOO |
+             MIDGARD_NO_AUTO32;
+
    case 0x620:
       return MIDGARD_OLD_BLEND | MIDGARD_BROKEN_BLEND_LOADS |
              MIDGARD_BROKEN_LOD | MIDGARD_NO_UPPER_ALU | MIDGARD_NO_OOO;

src/panfrost/util/pan_collect_varyings.c

@@ -67,10 +67,17 @@ struct slot_info {
    unsigned index;
 };
 
+struct walk_varyings_data {
+   struct pan_shader_info *info;
+   struct slot_info *slots;
+};
+
 static bool
 walk_varyings(UNUSED nir_builder *b, nir_instr *instr, void *data)
 {
-   struct slot_info *slots = data;
+   struct walk_varyings_data *wv_data = data;
+   struct pan_shader_info *info = wv_data->info;
+   struct slot_info *slots = wv_data->slots;
 
    if (instr->type != nir_instr_type_intrinsic)
       return false;
@@ -113,8 +120,9 @@ walk_varyings(UNUSED nir_builder *b, nir_instr *instr, void *data)
     * only to determine the type, and the GL linker uses the type from the
     * fragment shader instead.
     */
-   bool flat = (intr->intrinsic != nir_intrinsic_load_interpolated_input);
-   nir_alu_type type = flat ? nir_type_uint : nir_type_float;
+   bool flat = intr->intrinsic != nir_intrinsic_load_interpolated_input;
+   bool auto32 = !info->quirk_no_auto32;
+   nir_alu_type type = (flat && auto32) ? nir_type_uint : nir_type_float;
 
    /* Demote interpolated float varyings to fp16 where possible. We do not
     * demote flat varyings, including integer varyings, due to various
@@ -161,7 +169,8 @@ pan_nir_collect_varyings(nir_shader *s, struct pan_shader_info *info)
       return;
 
    struct slot_info slots[64] = {0};
-   nir_shader_instructions_pass(s, walk_varyings, nir_metadata_all, slots);
+   struct walk_varyings_data wv_data = {info, slots};
+   nir_shader_instructions_pass(s, walk_varyings, nir_metadata_all, &wv_data);
 
    struct pan_shader_varying *varyings = (s->info.stage == MESA_SHADER_VERTEX)
                                             ? info->varyings.output

src/panfrost/util/pan_ir.h

@@ -288,6 +288,9 @@ struct pan_shader_info {
 
    uint32_t ubo_mask;
 
+   /* Quirk for GPUs that does not support auto32 types. */
+   bool quirk_no_auto32;
+
    union {
       struct bifrost_shader_info bifrost;
       struct midgard_shader_info midgard;