[PATCH i-g-t v2 2/2] DONT_MERGE: Add kms_modifier_list test to verify new modifier helper

[Jeevan B <jeevan.b@intel.com>]

Temporary test to check that the new lib modifier functions work and
print all supported modifiers.

Signed-off-by: Jeevan B <jeevan.b@intel.com>
---
 tests/kms_modifier_list.c | 127 ++++++++++++++++++++++++++++++++++++++
 tests/meson.build         |   1 +
 2 files changed, 128 insertions(+)
 create mode 100644 tests/kms_modifier_list.c

diff --git a/tests/kms_modifier_list.c b/tests/kms_modifier_list.c
new file mode 100644
index 000000000..2e203855c
--- /dev/null
+++ b/tests/kms_modifier_list.c
@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: MIT */
+
+/*
+ * Copyright © 2026 Intel Corporation
+ */
+
+#include "igt.h"
+#include "igt_modifier.h"
+#include <drm_fourcc.h>
+#include <inttypes.h>
+
+IGT_TEST_DESCRIPTION("Validate igt_get_basic_tiling_modifiers() and "
+                     "igt_get_all_supported_modifiers().");
+
+/**
+ * TEST: kms modifier list
+ * Category: Display
+ * Description: Validate the igt_get_basic_tiling_modifiers() and
+ *              igt_get_all_supported_modifiers() helper functions.
+ * Driver requirement: i915, xe
+ * Mega feature: General Display Features
+ */
+
+/**
+ * SUBTEST: basic-modifiers-nonempty
+ * Description: Verify that igt_get_basic_tiling_modifiers() returns a
+ *              non-empty list for DRM_FORMAT_XRGB8888.
+ *
+ * SUBTEST: all-modifiers-nonempty
+ * Description: Verify that igt_get_all_supported_modifiers() returns a
+ *              non-empty list for DRM_FORMAT_XRGB8888.
+ *
+ * SUBTEST: basic-subset-of-all
+ * Description: Verify that every modifier in the basic list is also present
+ *              in the all-modifiers list.
+ */
+
+static int drm_fd;
+static igt_display_t display;
+
+int igt_main()
+{
+	igt_fixture() {
+		drm_fd = drm_open_driver_master(DRIVER_ANY);
+		igt_display_require(&display, drm_fd);
+	}
+
+	igt_subtest("basic-modifiers-nonempty") {
+		uint64_t *mods = NULL;
+		int count;
+
+		count = igt_get_basic_tiling_modifiers(drm_fd,
+						       DRM_FORMAT_XRGB8888,
+						       &mods);
+		igt_assert_f(count > 0,
+			     "igt_get_basic_tiling_modifiers() returned empty list\n");
+
+		igt_info("Basic modifiers (%d):\n", count);
+		for (int i = 0; i < count; i++) {
+			const char *name = igt_fb_modifier_name(mods[i]);
+			igt_info("  [basic] 0x%" PRIx64 " (%s)\n", mods[i], name);
+		}
+		free(mods);
+	}
+
+	igt_subtest("all-modifiers-nonempty") {
+		uint64_t *mods = NULL;
+		int count;
+
+		count = igt_get_all_supported_modifiers(drm_fd,
+							DRM_FORMAT_XRGB8888,
+							&mods);
+		igt_assert_f(count > 0,
+			     "igt_get_all_supported_modifiers() returned empty list\n");
+
+		igt_info("All supported modifiers (%d):\n", count);
+		for (int i = 0; i < count; i++) {
+			const char *name = igt_fb_modifier_name(mods[i]);
+			igt_info("  [all] 0x%" PRIx64 " (%s)\n", mods[i], name);
+		}
+
+		free(mods);
+	}
+
+	igt_subtest("basic-subset-of-all") {
+		uint64_t *basic = NULL, *all = NULL;
+		int basic_count, all_count;
+
+		basic_count = igt_get_basic_tiling_modifiers(drm_fd,
+							     DRM_FORMAT_XRGB8888,
+							     &basic);
+		all_count = igt_get_all_supported_modifiers(drm_fd,
+							    DRM_FORMAT_XRGB8888,
+							    &all);
+
+		igt_assert(basic_count > 0);
+		igt_assert(all_count > 0);
+
+		igt_info("Checking: basic-subset-of-all\n");
+		for (int i = 0; i < basic_count; i++) {
+			bool found = false;
+			const char *name = igt_fb_modifier_name(basic[i]);
+
+			for (int j = 0; j < all_count; j++) {
+				if (basic[i] == all[j]) {
+					found = true;
+					break;
+				}
+			}
+
+			igt_info("  [basic] 0x%" PRIx64 " (%s) -> %s\n",
+				 basic[i], name, found ? "FOUND" : "NOT FOUND");
+
+			igt_assert_f(found,
+				     "basic modifier 0x%"PRIx64" not in all-modifiers list\n",
+				     basic[i]);
+		}
+
+		free(basic);
+		free(all);
+	}
+
+	igt_fixture() {
+		igt_display_fini(&display);
+		drm_close_driver(drm_fd);
+	}
+}
diff --git a/tests/meson.build b/tests/meson.build
index cecb4a8ae..348cb9c74 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -46,6 +46,7 @@ test_progs = [
 	'kms_hdr',
 	'kms_invalid_mode',
 	'kms_lease',
+        'kms_modifier_list',
 	'kms_multipipe_modeset',
 	'kms_panel_fitting',
 	'kms_pipe_crc_basic',
-- 
2.43.0