[v3,15/15] drm/tests: hdmi: Add test for unsuccessful forced fallback to YUV420

Commit Message

Cristian Ciocaltea March 26, 2025, 10:20 a.m. UTC

Provide test to verify a forced fallback to YUV420 output cannot succeed
when driver doesn't advertise YUV420 support.

Signed-off-by: Cristian Ciocaltea <[e-mail]>
---
 drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 46 ++++++++++++++++++++++
 1 file changed, 46 insertions(+)

Patch

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 99bedb2d6f555b3b140256000dfa7491d2a8f515..c2976b42aa2aacd2a68a871bffe97e795ca713d4 100644
--- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
@@ -1493,6 +1493,51 @@  static void drm_test_check_max_tmds_rate_format_fallback_yuv420(struct kunit *te
 	drm_modeset_acquire_fini(&ctx);
 }
 
+/*
+ * Test that if a driver supports only RGB, but the chosen mode can be
+ * supported by the screen only in YUV420 output format, we end up with
+ * an unsuccessful forced fallback attempt.
+ */
+static void drm_test_check_driver_unsupported_fallback_yuv420(struct kunit *test)
+{
+	struct drm_atomic_helper_connector_hdmi_priv *priv;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_display_info *info;
+	struct drm_display_mode *yuv420_only_mode;
+	struct drm_connector *conn;
+	struct drm_device *drm;
+	struct drm_crtc *crtc;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid(test,
+				BIT(HDMI_COLORSPACE_RGB),
+				12,
+				test_edid_hdmi_1080p_rgb_yuv_4k_yuv420_dc_max_200mhz);
+	KUNIT_ASSERT_NOT_NULL(test, priv);
+
+	drm = &priv->drm;
+	crtc = priv->crtc;
+	conn = &priv->connector;
+	info = &conn->display_info;
+	KUNIT_ASSERT_TRUE(test, info->is_hdmi);
+	KUNIT_ASSERT_FALSE(test, conn->ycbcr_420_allowed);
+
+	yuv420_only_mode = drm_kunit_display_mode_from_cea_vic(test, drm, 95);
+	KUNIT_ASSERT_NOT_NULL(test, yuv420_only_mode);
+	KUNIT_ASSERT_TRUE(test, drm_mode_is_420_only(info, yuv420_only_mode));
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+	ret = drm_kunit_helper_enable_crtc_connector(test, drm,
+						     crtc, conn,
+						     yuv420_only_mode,
+						     &ctx);
+	KUNIT_EXPECT_LT(test, ret, 0);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
 /*
  * Test that if a driver and screen supports RGB and YUV formats, and we
  * try to set the VIC 1 mode, we end up with 8bpc RGB even if we could
@@ -1884,6 +1929,7 @@  static struct kunit_case drm_atomic_helper_connector_hdmi_check_tests[] = {
 	KUNIT_CASE(drm_test_check_max_tmds_rate_bpc_fallback_yuv420),
 	KUNIT_CASE(drm_test_check_max_tmds_rate_format_fallback_yuv422),
 	KUNIT_CASE(drm_test_check_max_tmds_rate_format_fallback_yuv420),
+	KUNIT_CASE(drm_test_check_driver_unsupported_fallback_yuv420),
 	KUNIT_CASE(drm_test_check_output_bpc_crtc_mode_changed),
 	KUNIT_CASE(drm_test_check_output_bpc_crtc_mode_not_changed),
 	KUNIT_CASE(drm_test_check_output_bpc_dvi),