diff --git a/src/gallium/drivers/crocus/crocus_screen.c b/src/gallium/drivers/crocus/crocus_screen.c
index a4d26910448..290506855df 100644
--- a/src/gallium/drivers/crocus/crocus_screen.c
+++ b/src/gallium/drivers/crocus/crocus_screen.c
@@ -410,6 +410,9 @@ crocus_init_screen_caps(struct crocus_screen *screen)
       PIPE_CONTEXT_PRIORITY_MEDIUM |
       PIPE_CONTEXT_PRIORITY_HIGH;
 
+   /* Let mesa/st lower for us */
+   caps->flatshade = false;
+
    caps->frontend_noop = true;
    // XXX: don't hardcode 00:00:02.0 PCI here
    caps->pci_group = 0;
diff --git a/src/gallium/drivers/crocus/crocus_state.c b/src/gallium/drivers/crocus/crocus_state.c
index 948aed0887d..888f22b734a 100644
--- a/src/gallium/drivers/crocus/crocus_state.c
+++ b/src/gallium/drivers/crocus/crocus_state.c
@@ -4855,9 +4855,6 @@ crocus_populate_fs_key(const struct crocus_context *ice,
 
    key->alpha_test_replicate_alpha = fb->nr_cbufs > 1 && zsa->cso.alpha_enabled;
 
-   key->flat_shade = rast->cso.flatshade &&
-      (info->inputs_read & (VARYING_BIT_COL0 | VARYING_BIT_COL1));
-
    const bool multisample_fbo = rast->cso.multisample && fb->samples > 1;
    key->multisample_fbo = multisample_fbo ? ELK_ALWAYS : ELK_NEVER;
    key->persample_interp =
diff --git a/src/gallium/drivers/iris/iris_context.h b/src/gallium/drivers/iris/iris_context.h
index 96fc1669d89..fd887ef9a32 100644
--- a/src/gallium/drivers/iris/iris_context.h
+++ b/src/gallium/drivers/iris/iris_context.h
@@ -278,7 +278,6 @@ struct iris_fs_prog_key {
    uint8_t color_outputs_valid;
 
    unsigned nr_color_regions:5;
-   bool flat_shade:1;
    bool alpha_test_replicate_alpha:1;
    bool alpha_to_coverage:1;
    bool persample_interp:1;
@@ -286,7 +285,7 @@ struct iris_fs_prog_key {
    bool force_dual_color_blend:1;
    bool coherent_fb_fetch:1;
    enum intel_vue_layout vue_layout:2;
-   uint64_t padding:42;
+   uint64_t padding:43;
 };
 
 struct iris_cs_prog_key {
diff --git a/src/gallium/drivers/iris/iris_program.c b/src/gallium/drivers/iris/iris_program.c
index 2451aac50f0..155d862dda4 100644
--- a/src/gallium/drivers/iris/iris_program.c
+++ b/src/gallium/drivers/iris/iris_program.c
@@ -576,7 +576,6 @@ iris_to_brw_fs_key(const struct iris_screen *screen,
    return (struct brw_wm_prog_key) {
       BRW_KEY_INIT(key->base, key->vue_layout),
       .nr_color_regions = key->nr_color_regions,
-      .flat_shade = key->flat_shade,
       .alpha_test_replicate_alpha = key->alpha_test_replicate_alpha,
       .alpha_to_coverage = key->alpha_to_coverage ? INTEL_ALWAYS : INTEL_NEVER,
       .persample_interp = key->persample_interp ? INTEL_ALWAYS : INTEL_NEVER,
@@ -662,7 +661,6 @@ iris_to_elk_fs_key(const struct iris_screen *screen,
       ELK_KEY_INIT(screen->devinfo->ver, key->base.program_string_id,
                    key->base.limit_trig_input_range),
       .nr_color_regions = key->nr_color_regions,
-      .flat_shade = key->flat_shade,
       .alpha_test_replicate_alpha = key->alpha_test_replicate_alpha,
       .alpha_to_coverage = key->alpha_to_coverage ? ELK_ALWAYS : ELK_NEVER,
       .persample_interp = key->persample_interp ? ELK_ALWAYS : ELK_NEVER,
diff --git a/src/gallium/drivers/iris/iris_screen.c b/src/gallium/drivers/iris/iris_screen.c
index 8e172801ed5..292a293be9f 100644
--- a/src/gallium/drivers/iris/iris_screen.c
+++ b/src/gallium/drivers/iris/iris_screen.c
@@ -447,6 +447,9 @@ iris_init_screen_caps(struct iris_screen *screen)
       PIPE_CONTEXT_PRIORITY_MEDIUM |
       PIPE_CONTEXT_PRIORITY_HIGH;
 
+   /* Let mesa/st lower for us */
+   caps->flatshade = false;
+
    caps->frontend_noop = true;
 
    // XXX: don't hardcode 00:00:02.0 PCI here
diff --git a/src/gallium/drivers/iris/iris_state.c b/src/gallium/drivers/iris/iris_state.c
index 6d15195cf24..c9bd99c830e 100644
--- a/src/gallium/drivers/iris/iris_state.c
+++ b/src/gallium/drivers/iris/iris_state.c
@@ -5046,9 +5046,6 @@ iris_populate_fs_key(const struct iris_context *ice,
 
    key->alpha_test_replicate_alpha = fb->nr_cbufs > 1 && zsa->alpha_enabled;
 
-   key->flat_shade = rast->flatshade &&
-      (info->inputs_read & (VARYING_BIT_COL0 | VARYING_BIT_COL1));
-
    key->persample_interp = rast->force_persample_interp;
    key->multisample_fbo = rast->multisample && fb->samples > 1;
 
diff --git a/src/intel/compiler/brw_compiler.h b/src/intel/compiler/brw_compiler.h
index 75a9abee944..ad20e4b87fa 100644
--- a/src/intel/compiler/brw_compiler.h
+++ b/src/intel/compiler/brw_compiler.h
@@ -395,7 +395,6 @@ struct brw_wm_prog_key {
    uint8_t color_outputs_valid;
 
    /* Some collection of BRW_WM_IZ_* */
-   bool flat_shade:1;
    unsigned nr_color_regions:5;
    bool alpha_test_replicate_alpha:1;
    enum intel_sometimes alpha_to_coverage:2;
@@ -426,7 +425,7 @@ struct brw_wm_prog_key {
    bool coarse_pixel:1;
    bool null_push_constant_tbimr_workaround:1;
    bool api_sample_shading:1;
-   unsigned pad:1;
+   unsigned pad:2;
 };
 
 static inline bool
diff --git a/src/intel/compiler/brw_debug_recompile.c b/src/intel/compiler/brw_debug_recompile.c
index 56c3609f03c..5f644e1ae59 100644
--- a/src/intel/compiler/brw_debug_recompile.c
+++ b/src/intel/compiler/brw_debug_recompile.c
@@ -132,7 +132,6 @@ debug_fs_recompile(const struct brw_compiler *c, void *log,
 {
    bool found = false;
 
-   found |= check("flat shading", flat_shade);
    found |= check("number of color buffers", nr_color_regions);
    found |= check("MRT alpha test", alpha_test_replicate_alpha);
    found |= check("alpha to coverage", alpha_to_coverage);
diff --git a/src/intel/compiler/brw_nir.c b/src/intel/compiler/brw_nir.c
index b5cbc40ec6b..962debf6989 100644
--- a/src/intel/compiler/brw_nir.c
+++ b/src/intel/compiler/brw_nir.c
@@ -958,19 +958,8 @@ brw_nir_lower_fs_inputs(nir_shader *nir,
    nir_foreach_shader_in_variable(var, nir) {
       var->data.driver_location = var->data.location;
 
-      /* Apply default interpolation mode.
-       *
-       * Everything defaults to smooth except for the legacy GL color
-       * built-in variables, which might be flat depending on API state.
-       */
-      if (var->data.interpolation == INTERP_MODE_NONE) {
-         const bool flat = key->flat_shade &&
-            (var->data.location == VARYING_SLOT_COL0 ||
-             var->data.location == VARYING_SLOT_COL1);
-
-         var->data.interpolation = flat ? INTERP_MODE_FLAT
-                                        : INTERP_MODE_SMOOTH;
-      }
+      if (var->data.interpolation == INTERP_MODE_NONE)
+         var->data.interpolation = INTERP_MODE_SMOOTH;
    }
 
    NIR_PASS(_, nir, nir_lower_io,
diff --git a/src/intel/compiler/elk/elk_compiler.h b/src/intel/compiler/elk/elk_compiler.h
index 5001eaad4d7..97b9f632431 100644
--- a/src/intel/compiler/elk/elk_compiler.h
+++ b/src/intel/compiler/elk/elk_compiler.h
@@ -490,7 +490,6 @@ struct elk_wm_prog_key {
    /* Some collection of ELK_WM_IZ_* */
    uint8_t iz_lookup;
    bool stats_wm:1;
-   bool flat_shade:1;
    unsigned nr_color_regions:5;
    bool emit_alpha_test:1;
    enum compare_func alpha_test_func:3; /* < For Gfx4/5 MRT alpha test */
@@ -517,7 +516,7 @@ struct elk_wm_prog_key {
    bool coherent_fb_fetch:1;
    bool ignore_sample_mask_out:1;
 
-   uint64_t padding:57;
+   uint64_t padding:58;
 };
 
 struct elk_cs_prog_key {
diff --git a/src/intel/compiler/elk/elk_debug_recompile.c b/src/intel/compiler/elk/elk_debug_recompile.c
index 925f15beea0..31ffdfe843d 100644
--- a/src/intel/compiler/elk/elk_debug_recompile.c
+++ b/src/intel/compiler/elk/elk_debug_recompile.c
@@ -160,7 +160,6 @@ debug_fs_recompile(const struct elk_compiler *c, void *log,
    found |= check("alphatest, computed depth, depth test, or depth write",
                   iz_lookup);
    found |= check("depth statistics", stats_wm);
-   found |= check("flat shading", flat_shade);
    found |= check("number of color buffers", nr_color_regions);
    found |= check("MRT alpha test", alpha_test_replicate_alpha);
    found |= check("alpha to coverage", alpha_to_coverage);
diff --git a/src/intel/compiler/elk/elk_nir.c b/src/intel/compiler/elk/elk_nir.c
index a94fe9d90d9..7c476eeb226 100644
--- a/src/intel/compiler/elk/elk_nir.c
+++ b/src/intel/compiler/elk/elk_nir.c
@@ -567,19 +567,8 @@ elk_nir_lower_fs_inputs(nir_shader *nir,
    nir_foreach_shader_in_variable(var, nir) {
       var->data.driver_location = var->data.location;
 
-      /* Apply default interpolation mode.
-       *
-       * Everything defaults to smooth except for the legacy GL color
-       * built-in variables, which might be flat depending on API state.
-       */
-      if (var->data.interpolation == INTERP_MODE_NONE) {
-         const bool flat = key->flat_shade &&
-            (var->data.location == VARYING_SLOT_COL0 ||
-             var->data.location == VARYING_SLOT_COL1);
-
-         var->data.interpolation = flat ? INTERP_MODE_FLAT
-                                        : INTERP_MODE_SMOOTH;
-      }
+      if (var->data.interpolation == INTERP_MODE_NONE)
+         var->data.interpolation = INTERP_MODE_SMOOTH;
 
       /* On Ironlake and below, there is only one interpolation mode.
        * Centroid interpolation doesn't mean anything on this hardware --