diff --git a/src/amd/common/nir/ac_nir.h b/src/amd/common/nir/ac_nir.h
index db67fdfdaae..acf4fc509f1 100644
--- a/src/amd/common/nir/ac_nir.h
+++ b/src/amd/common/nir/ac_nir.h
@@ -275,7 +275,21 @@ typedef struct {
    bool load_sample_positions_always_loads_current_ones;
    bool dynamic_rasterization_samples;
    int force_front_face; /* 0 -> keep, 1 -> set to true, -1 -> set to false */
-   unsigned ps_iter_samples; /* >= 2 forces sample interpolation, affects sample_mask_in lowering */
+
+   /* barycentrics:
+    *    ps_iter_samples >= 2:
+    *       * All barycentrics are changed to per-sample interpolation except at_offset/at_sample.
+    *       * barycentric_at_sample(sample_id) is replaced by barycentric_sample.
+    *
+    * sample_mask_in:
+    *    ps_iter_samples == 2, 4:
+    *       * sample_mask_in is changed to (sample_mask_in & (ps_iter_mask << sample_id))
+    *    ps_iter_samples == 8:
+    *       * sample_mask_in is replaced by 1 << sample_id.
+    *
+    * When ps_iter_samples is equal to rasterization samples, set ps_iter_samples = 8 for this pass.
+    */
+   unsigned ps_iter_samples;
 
    /* fbfetch_output */
    bool fbfetch_is_1D;
diff --git a/src/amd/common/nir/ac_nir_lower_ps_early.c b/src/amd/common/nir/ac_nir_lower_ps_early.c
index f716df0dae3..0aab96a94ac 100644
--- a/src/amd/common/nir/ac_nir_lower_ps_early.c
+++ b/src/amd/common/nir/ac_nir_lower_ps_early.c
@@ -383,19 +383,26 @@ lower_ps_intrinsic(nir_builder *b, nir_intrinsic_instr *intrin, void *state)
       return true;
    case nir_intrinsic_load_barycentric_at_sample: {
       unsigned mode = nir_intrinsic_interp_mode(intrin);
+      nir_def *sample_id = intrin->src[0].ssa;
 
       if (s->options->force_center_interp_no_msaa) {
          nir_def_replace(&intrin->def, nir_load_barycentric_pixel(b, 32, .interp_mode = mode));
          return true;
       }
 
+      if (s->options->ps_iter_samples >= 2 &&
+          sample_id->parent_instr->type == nir_instr_type_intrinsic &&
+          nir_instr_as_intrinsic(sample_id->parent_instr)->intrinsic == nir_intrinsic_load_sample_id) {
+         nir_def_replace(&intrin->def, nir_load_barycentric_sample(b, 32, .interp_mode = mode));
+         return true;
+      }
+
       /* If load_sample_positions_always_loads_current_ones is true, load_sample_positions_amd
        * always loads the sample positions that are currently set in the rasterizer state
        * even if MSAA is disabled.
        */
       nir_def *num_samples = s->options->load_sample_positions_always_loads_current_ones ?
                                 nir_undef(b, 1, 32) : nir_load_rasterization_samples_amd(b);
-      nir_def *sample_id = intrin->src[0].ssa;
       nir_def *sample_pos = nir_load_sample_positions_amd(b, 32, sample_id, num_samples);
       sample_pos = nir_fadd_imm(b, sample_pos, -0.5f);
 
diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index e13b35b82ed..856e3141338 100644
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -2487,11 +2487,11 @@ static struct nir_shader *si_get_nir_shader(struct si_shader *shader, struct si_
                                         key->ps.mono.interpolate_at_sample_force_center,
          .load_sample_positions_always_loads_current_ones = true,
          .force_front_face = key->ps.opt.force_front_face_input,
-         /* This forces per-sample interpolation (if at least 2) and lowers sample_mask_in. */
+         /* This does a lot of things. See the description in ac_nir_lower_ps_early_options. */
          .ps_iter_samples = key->ps.part.prolog.samplemask_log_ps_iter ?
                               (1 << key->ps.part.prolog.samplemask_log_ps_iter) :
                               (key->ps.part.prolog.force_persp_sample_interp ||
-                               key->ps.part.prolog.force_linear_sample_interp ? 2 : 1),
+                               key->ps.part.prolog.force_linear_sample_interp ? 2 : 0),
 
          .fbfetch_is_1D = key->ps.mono.fbfetch_is_1D,
          .fbfetch_layered = key->ps.mono.fbfetch_layered,