drm/vc4: tests: Add unit test suite for the PV muxing

The HVS to PixelValve muxing code is fairly error prone and has a bunch
of arbitrary constraints due to the hardware setup.

Let's create a test suite that makes sure that the possible combinations
work and the invalid ones don't.

Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Link: https://lore.kernel.org/r/20221123-rpi-kunit-tests-v3-19-4615a663a84a@cerno.tech
Signed-off-by: Maxime Ripard <maxime@cerno.tech>

drivers/gpu/drm/vc4/Makefile

@@ -29,7 +29,8 @@ vc4-$(CONFIG_DRM_VC4_KUNIT_TEST) += \
 	tests/vc4_mock.o \
 	tests/vc4_mock_crtc.o \
 	tests/vc4_mock_output.o \
-	tests/vc4_mock_plane.o
+	tests/vc4_mock_plane.o \
+	tests/vc4_test_pv_muxing.o
 
 vc4-$(CONFIG_DEBUG_FS) += vc4_debugfs.o
 

drivers/gpu/drm/vc4/tests/vc4_mock.h

@@ -53,8 +53,11 @@ struct vc4_dummy_output *vc4_dummy_output(struct kunit *test,
 struct vc4_dev *vc4_mock_device(struct kunit *test);
 struct vc4_dev *vc5_mock_device(struct kunit *test);
 
-int vc4_mock_atomic_add_output(struct kunit *test, struct drm_device *drm,
-			       enum vc4_encoder_type type,
-			       struct drm_atomic_state *state);
+int vc4_mock_atomic_add_output(struct kunit *test,
+			       struct drm_atomic_state *state,
+			       enum vc4_encoder_type type);
+int vc4_mock_atomic_del_output(struct kunit *test,
+			       struct drm_atomic_state *state,
+			       enum vc4_encoder_type type);
 
 #endif // VC4_MOCK_H_

drivers/gpu/drm/vc4/tests/vc4_mock_output.c

@@ -61,16 +61,17 @@ static const struct drm_display_mode default_mode = {
 	DRM_SIMPLE_MODE(640, 480, 64, 48)
 };
 
-int vc4_mock_atomic_add_output(struct kunit *test, struct drm_device *drm,
-			       enum vc4_encoder_type type,
-			       struct drm_atomic_state *state)
+int vc4_mock_atomic_add_output(struct kunit *test,
+			       struct drm_atomic_state *state,
+			       enum vc4_encoder_type type)
 {
+	struct drm_device *drm = state->dev;
+	struct drm_connector_state *conn_state;
+	struct drm_crtc_state *crtc_state;
 	struct vc4_dummy_output *output;
 	struct drm_connector *conn;
-	struct drm_connector_state *conn_state;
 	struct drm_encoder *encoder;
 	struct drm_crtc *crtc;
-	struct drm_crtc_state *crtc_state;
 	int ret;
 
 	encoder = vc4_find_encoder_by_type(drm, type);
@@ -97,3 +98,41 @@ int vc4_mock_atomic_add_output(struct kunit *test, struct drm_device *drm,
 
 	return 0;
 }
+
+int vc4_mock_atomic_del_output(struct kunit *test,
+			       struct drm_atomic_state *state,
+			       enum vc4_encoder_type type)
+{
+	struct drm_device *drm = state->dev;
+	struct drm_connector_state *conn_state;
+	struct drm_crtc_state *crtc_state;
+	struct vc4_dummy_output *output;
+	struct drm_connector *conn;
+	struct drm_encoder *encoder;
+	struct drm_crtc *crtc;
+	int ret;
+
+	encoder = vc4_find_encoder_by_type(drm, type);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, encoder);
+
+	crtc = vc4_find_crtc_for_encoder(test, drm, encoder);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc);
+
+	crtc_state = drm_atomic_get_crtc_state(state, crtc);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
+
+	crtc_state->active = false;
+
+	ret = drm_atomic_set_mode_for_crtc(crtc_state, NULL);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	output = container_of(encoder, struct vc4_dummy_output, encoder.base);
+	conn = &output->connector;
+	conn_state = drm_atomic_get_connector_state(state, conn);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
+
+	ret = drm_atomic_set_crtc_for_connector(conn_state, NULL);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	return 0;
+}