diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
index 6410eca57a99..c46aba6cfe80 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -215,6 +215,34 @@ static const struct drm_connector_hdmi_funcs reject_over_165mhz_connector_hdmi_f
 	},
 };
 
+static int accept_scrambler_enable(struct drm_connector *connector)
+{
+	return 0;
+}
+
+static int accept_scrambler_disable(struct drm_connector *connector)
+{
+	return 0;
+}
+
+static const struct drm_connector_hdmi_funcs scrambler_connector_hdmi_funcs = {
+	.vendor = "Vendor",
+	.product = "Product",
+	.supported_hdmi_ver = HDMI_VERSION_2_0,
+	.supported_formats = BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444),
+	.max_bpc = 8,
+	.scrambler_enable	 = accept_scrambler_enable,
+	.scrambler_disable	 = accept_scrambler_disable,
+	.avi = {
+		.clear_infoframe = accept_infoframe_clear_infoframe,
+		.write_infoframe = accept_infoframe_write_infoframe,
+	},
+	.hdmi = {
+		.clear_infoframe = accept_infoframe_clear_infoframe,
+		.write_infoframe = accept_infoframe_write_infoframe,
+	},
+};
+
 static int dummy_connector_get_modes(struct drm_connector *connector)
 {
 	struct drm_atomic_helper_connector_hdmi_priv *priv =
@@ -2252,6 +2280,127 @@ static void drm_test_check_disable_connector(struct kunit *test)
 	drm_modeset_acquire_fini(&ctx);
 }
 
+/*
+ * Test that on an HDMI connector with source+sink scrambling support, driving
+ * a sub-340 MHz CEA mode, we end up with scrambler_needed cleared.
+ */
+static void drm_test_check_scrambler_needed_low_rate(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_connector_state *conn_state;
+	struct drm_display_info *info;
+	struct drm_display_mode *low_rate_mode;
+	struct drm_connector *conn;
+	struct drm_device *drm;
+	struct drm_crtc *crtc;
+	unsigned long long rate;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				&scrambler_connector_hdmi_funcs,
+				test_edid_hdmi_4k_rgb_yuv420_dc_max_600mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	drm = &priv->drm;
+	crtc = priv->crtc;
+	conn = &priv->connector;
+	info = &conn->display_info;
+	KUNIT_ASSERT_TRUE(test, drm_connector_hdmi_scrambler_supported(conn));
+	KUNIT_ASSERT_TRUE(test, info->is_hdmi);
+	KUNIT_ASSERT_TRUE(test, info->hdmi.scdc.supported);
+	KUNIT_ASSERT_TRUE(test, info->hdmi.scdc.scrambling.supported);
+
+	low_rate_mode = drm_kunit_display_mode_from_cea_vic(test, drm, 16);
+	KUNIT_ASSERT_NOT_NULL(test, low_rate_mode);
+
+	rate = drm_hdmi_compute_mode_clock(low_rate_mode, 8, DRM_OUTPUT_COLOR_FORMAT_RGB444);
+	KUNIT_ASSERT_LT(test, rate, HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+retry_conn_enable:
+	ret = drm_kunit_helper_enable_crtc_connector(test, drm, crtc, conn,
+						     low_rate_mode, &ctx);
+	if (ret == -EDEADLK) {
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_enable;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	conn_state = conn->state;
+	KUNIT_ASSERT_NOT_NULL(test, conn_state);
+
+	KUNIT_EXPECT_LE(test, conn_state->hdmi.tmds_char_rate,
+			HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ);
+	KUNIT_EXPECT_FALSE(test, conn_state->hdmi.scrambler_needed);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test that on an HDMI connector with source+sink scrambling support, driving
+ * the 4K@60 RGB preferred mode (~594 MHz TMDS, above the 340 MHz threshold),
+ * we end up with scrambler_needed set.
+ */
+static void drm_test_check_scrambler_needed_high_rate(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_connector_state *conn_state;
+	struct drm_display_info *info;
+	struct drm_display_mode *preferred;
+	struct drm_connector *conn;
+	struct drm_device *drm;
+	struct drm_crtc *crtc;
+	unsigned long long rate;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				&scrambler_connector_hdmi_funcs,
+				test_edid_hdmi_4k_rgb_yuv420_dc_max_600mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	drm = &priv->drm;
+	crtc = priv->crtc;
+	conn = &priv->connector;
+	info = &conn->display_info;
+	KUNIT_ASSERT_TRUE(test, drm_connector_hdmi_scrambler_supported(conn));
+	KUNIT_ASSERT_TRUE(test, info->is_hdmi);
+	KUNIT_ASSERT_TRUE(test, info->hdmi.scdc.supported);
+	KUNIT_ASSERT_TRUE(test, info->hdmi.scdc.scrambling.supported);
+
+	preferred = find_preferred_mode(conn);
+	KUNIT_ASSERT_NOT_NULL(test, preferred);
+
+	rate = drm_hdmi_compute_mode_clock(preferred, 8, DRM_OUTPUT_COLOR_FORMAT_RGB444);
+	KUNIT_ASSERT_GT(test, rate, HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+retry_conn_enable:
+	ret = drm_kunit_helper_enable_crtc_connector(test, drm, crtc, conn,
+						     preferred, &ctx);
+	if (ret == -EDEADLK) {
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_enable;
+	}
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	conn_state = conn->state;
+	KUNIT_ASSERT_NOT_NULL(test, conn_state);
+
+	KUNIT_EXPECT_GT(test, conn_state->hdmi.tmds_char_rate,
+			HDMI_1_3_TMDS_CHAR_RATE_MAX_HZ);
+	KUNIT_EXPECT_TRUE(test, conn_state->hdmi.scrambler_needed);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
 struct color_format_test_param {
 	enum drm_connector_color_format fmt;
 	enum drm_output_color_format expected;
@@ -2494,6 +2643,8 @@ static struct kunit_case drm_atomic_helper_connector_hdmi_check_tests[] = {
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_8bpc),
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_10bpc),
 	KUNIT_CASE(drm_test_check_tmds_char_rate_rgb_12bpc),
+	KUNIT_CASE(drm_test_check_scrambler_needed_low_rate),
+	KUNIT_CASE(drm_test_check_scrambler_needed_high_rate),
 	KUNIT_CASE_PARAM(drm_test_check_hdmi_color_format,
 			 check_hdmi_color_format_gen_params),
 	KUNIT_CASE_PARAM(drm_test_check_hdmi_color_format_420_only,