drm/tests: hdmi: Add max TMDS rate fallback tests for YUV420 mode

Provide tests to verify drm_atomic_helper_connector_hdmi_check() helper
fallback behavior when using YUV420 output format.

Acked-by: Maxime Ripard <[e-mail]>
Signed-off-by: Cristian Ciocaltea <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Maxime Ripard <[e-mail]>

drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c

···
 
 /*
  * Test that if:
+ * - We have an HDMI connector and a display supporting both RGB and YUV420
+ * - The chosen mode can be supported in YUV420 output format only
+ * - The chosen mode has a TMDS character rate higher than the display
+ *   supports in YUV420/12bpc
+ * - The chosen mode has a TMDS character rate lower than the display
+ *   supports in YUV420/10bpc.
+ *
+ * Then we will pick the latter, and the computed TMDS character rate
+ * will be equal to 1.25 * 0.5 times the mode pixel clock.
+ */
+static void drm_test_check_max_tmds_rate_bpc_fallback_yuv420(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 *yuv420_only_mode;
+	unsigned long long rate;
+	struct drm_connector *conn;
+	struct drm_device *drm;
+	struct drm_crtc *crtc;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(HDMI_COLORSPACE_RGB) |
+				BIT(HDMI_COLORSPACE_YUV420),
+				12,
+				&dummy_connector_hdmi_funcs,
+				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_GT(test, info->max_tmds_clock, 0);
+	KUNIT_ASSERT_TRUE(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));
+
+	rate = drm_hdmi_compute_mode_clock(yuv420_only_mode, 12, HDMI_COLORSPACE_YUV420);
+	KUNIT_ASSERT_GT(test, rate, info->max_tmds_clock * 1000);
+
+	rate = drm_hdmi_compute_mode_clock(yuv420_only_mode, 10, HDMI_COLORSPACE_YUV420);
+	KUNIT_ASSERT_LT(test, rate, info->max_tmds_clock * 1000);
+
+	drm_modeset_acquire_init(&ctx, 0);
+
+retry_conn_enable:
+	ret = drm_kunit_helper_enable_crtc_connector(test, drm, crtc, conn,
+						     yuv420_only_mode, &ctx);
+	if (ret == -EDEADLK) {
+		ret = drm_modeset_backoff(&ctx);
+		if (!ret)
+			goto retry_conn_enable;
+	}
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	conn_state = conn->state;
+	KUNIT_ASSERT_NOT_NULL(test, conn_state);
+
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_bpc, 10);
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, HDMI_COLORSPACE_YUV420);
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.tmds_char_rate, yuv420_only_mode->clock * 625);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test that if:
  * - We have an HDMI connector supporting both RGB and YUV422 and up to
  *   12 bpc
  * - The chosen mode has a TMDS character rate higher than the display
···
 	KUNIT_ASSERT_NOT_NULL(test, conn_state);
 
 	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_bpc, 10);
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, HDMI_COLORSPACE_RGB);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+}
+
+/*
+ * Test that if:
+ * - We have an HDMI connector supporting both RGB and YUV420 and up to
+ *   12 bpc
+ * - The chosen mode has a TMDS character rate higher than the display
+ *   supports in RGB/10bpc but lower than the display supports in
+ *   RGB/8bpc
+ * - The chosen mode has a TMDS character rate lower than the display
+ *   supports in YUV420/12bpc.
+ *
+ * Then we will prefer to keep the RGB format with a lower bpc over
+ * picking YUV420.
+ */
+static void drm_test_check_max_tmds_rate_bpc_fallback_ignore_yuv420(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;
+	unsigned long long rate;
+	struct drm_connector *conn;
+	struct drm_device *drm;
+	struct drm_crtc *crtc;
+	int ret;
+
+	priv = drm_kunit_helper_connector_hdmi_init_with_edid_funcs(test,
+				BIT(HDMI_COLORSPACE_RGB) |
+				BIT(HDMI_COLORSPACE_YUV420),
+				12,
+				&dummy_connector_hdmi_funcs,
+				test_edid_hdmi_4k_rgb_yuv420_dc_max_340mhz);
+	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_GT(test, info->max_tmds_clock, 0);
+	KUNIT_ASSERT_TRUE(test, conn->ycbcr_420_allowed);
+
+	preferred = find_preferred_mode(conn);
+	KUNIT_ASSERT_NOT_NULL(test, preferred);
+	KUNIT_ASSERT_FALSE(test, preferred->flags & DRM_MODE_FLAG_DBLCLK);
+	KUNIT_ASSERT_TRUE(test, drm_mode_is_420_also(info, preferred));
+
+	rate = drm_hdmi_compute_mode_clock(preferred, 8, HDMI_COLORSPACE_RGB);
+	KUNIT_ASSERT_LT(test, rate, info->max_tmds_clock * 1000);
+
+	rate = drm_hdmi_compute_mode_clock(preferred, 10, HDMI_COLORSPACE_RGB);
+	KUNIT_ASSERT_GT(test, rate, info->max_tmds_clock * 1000);
+
+	rate = drm_hdmi_compute_mode_clock(preferred, 12, HDMI_COLORSPACE_YUV420);
+	KUNIT_ASSERT_LT(test, rate, info->max_tmds_clock * 1000);
+
+	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_EXPECT_EQ(test, ret, 0);
+
+	conn_state = conn->state;
+	KUNIT_ASSERT_NOT_NULL(test, conn_state);
+
+	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_bpc, 8);
 	KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, HDMI_COLORSPACE_RGB);
 
 	drm_modeset_drop_locks(&ctx);
···
 	KUNIT_CASE(drm_test_check_disable_connector),
 	KUNIT_CASE(drm_test_check_hdmi_funcs_reject_rate),
 	KUNIT_CASE(drm_test_check_max_tmds_rate_bpc_fallback_rgb),
+	KUNIT_CASE(drm_test_check_max_tmds_rate_bpc_fallback_yuv420),
 	KUNIT_CASE(drm_test_check_max_tmds_rate_bpc_fallback_ignore_yuv422),
+	KUNIT_CASE(drm_test_check_max_tmds_rate_bpc_fallback_ignore_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),