[PATCH v8 37/39] drm/tests: hdmi_state_helper: Cover source-side scrambling decision
Cristian Ciocaltea
cristian.ciocaltea at collabora.com
Thu Jul 2 07:46:50 PDT 2026
Add two atomic-check cases that initialise an HDMI 2.0 connector via
drm_connector_hdmi_caps (so the core infers scrambler_supported and the
600 MHz TMDS limit) and assert that conn_state->hdmi.scrambler_needed
stays clear for a 1080p at 60 CEA mode (~148.5 MHz TMDS) and is set for the
4K at 60 RGB preferred mode (~594 MHz TMDS), straddling the 340 MHz
threshold.
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea at collabora.com>
---
drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 160 +++++++++++++++++++++
1 file changed, 160 insertions(+)
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 b8ae5fad2794..7cd6bd422b0b 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -20,6 +20,8 @@
#include <drm/display/drm_hdmi_helper.h>
#include <drm/display/drm_hdmi_state_helper.h>
+#include <linux/hdmi.h>
+
#include "../drm_crtc_internal.h"
#include <kunit/test.h>
@@ -194,6 +196,29 @@ static const struct drm_connector_hdmi_funcs accept_connector_hdmi_funcs = {
},
};
+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 = {
+ .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 =
@@ -2265,6 +2290,139 @@ 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_connector_hdmi_caps caps = {
+ .supported_hdmi_ver = HDMI_VERSION_2_0,
+ .supported_formats = BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444),
+ .max_bpc = 8,
+ };
+ 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_caps_edid_funcs(test,
+ &caps,
+ &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, conn->hdmi.scrambler_supported);
+ 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 at 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_connector_hdmi_caps caps = {
+ .supported_hdmi_ver = HDMI_VERSION_2_0,
+ .supported_formats = BIT(DRM_OUTPUT_COLOR_FORMAT_RGB444),
+ .max_bpc = 8,
+ };
+ 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_caps_edid_funcs(test,
+ &caps,
+ &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, conn->hdmi.scrambler_supported);
+ 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;
@@ -2505,6 +2663,8 @@ 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,
--
2.54.0
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