[PATCH 31/59] drm/amd/display: Test affected MST DSC CRTC selection

[WHAT]
Add KUnit tests for add_affected_mst_dsc_crtcs() covering an empty commit,
a writeback connector, a connector that is not behind an MST branch, a
connector bound to a different CRTC, and a disabled connector whose old
state decides which CRTC is affected.

Assisted-by: Copilot:Claude-Opus-5 GPT-5.6-Sol
Reviewed-by: Bhawanpreet Lakha <[email protected]>
Signed-off-by: Alex Hung <[email protected]>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |   4 +-
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |   2 +
 .../display/amdgpu_dm/tests/amdgpu_dm_test.c  | 142 ++++++++++++++++++
 3 files changed, 147 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 5c4aac207e8f..9d233b18f2df 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -6007,7 +6007,8 @@ struct __drm_planes_state *amdgpu_dm_get_next_zpos(
 	return &state->planes[highest_i];
 }
 
-static int add_affected_mst_dsc_crtcs(struct drm_atomic_commit *state, struct drm_crtc *crtc)
+STATIC_IFN_KUNIT int add_affected_mst_dsc_crtcs(struct drm_atomic_commit *state,
+						struct drm_crtc *crtc)
 {
 	struct drm_connector *connector;
 	struct drm_connector_state *conn_state, *old_conn_state;
@@ -6036,6 +6037,7 @@ static int add_affected_mst_dsc_crtcs(struct drm_atomic_commit *state, struct dr
 
 	return drm_dp_mst_add_affected_dsc_crtcs(state, &aconnector->mst_root->mst_mgr);
 }
+EXPORT_IF_KUNIT(add_affected_mst_dsc_crtcs);
 
 static bool amdgpu_dm_crtc_mem_type_changed(struct drm_device *dev,
 					    struct drm_atomic_commit *state,
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index 6e078be5bc5e..a48154ea62ae 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -1171,6 +1171,8 @@ struct dm_atomic_state *dm_atomic_get_new_state(struct drm_atomic_commit *state)
 struct drm_private_state *dm_atomic_duplicate_state(struct drm_private_obj *obj);
 void dm_atomic_destroy_state(struct drm_private_obj *obj,
 			     struct drm_private_state *state);
+int add_affected_mst_dsc_crtcs(struct drm_atomic_commit *state,
+			       struct drm_crtc *crtc);
 int dm_plane_layer_index_cmp(const void *a, const void *b);
 int fill_plane_color_attributes(const struct drm_plane_state *plane_state,
 				const enum surface_pixel_format format,
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_test.c
index 66c35a22c45e..2afa73a07ebd 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_test.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_test.c
@@ -1282,6 +1282,142 @@ static void dm_test_atomic_duplicate_state_no_context(struct kunit *test)
 	KUNIT_EXPECT_NULL(test, dm_atomic_duplicate_state(obj));
 }
 
+/* Tests for add_affected_mst_dsc_crtcs() */
+
+/**
+ * dm_test_add_affected_mst_dsc_crtcs_no_connector - Test an empty state adds nothing
+ * @test: The KUnit test context
+ */
+static void dm_test_add_affected_mst_dsc_crtcs_no_connector(struct kunit *test)
+{
+	struct amdgpu_device *adev = dm_kunit_alloc_adev(test);
+	struct drm_atomic_commit *state = dm_test_alloc_commit(test, adev);
+	struct drm_crtc *crtc;
+
+	crtc = kunit_kzalloc(test, sizeof(*crtc), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, crtc);
+
+	KUNIT_EXPECT_EQ(test, add_affected_mst_dsc_crtcs(state, crtc), 0);
+}
+
+/*
+ * Build an atomic state holding a single connector bound to @crtc.
+ */
+static struct drm_atomic_commit *
+dm_test_state_with_connector(struct kunit *test, struct drm_connector *connector,
+			     struct drm_crtc *crtc)
+{
+	struct drm_connector_state *conn_state;
+	struct drm_atomic_commit *state;
+
+	state = kunit_kzalloc(test, sizeof(*state), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, state);
+	conn_state = kunit_kzalloc(test, sizeof(*conn_state), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, conn_state);
+
+	state->connectors = kunit_kzalloc(test, sizeof(*state->connectors),
+					  GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, state->connectors);
+
+	conn_state->crtc = crtc;
+	state->num_connector = 1;
+	state->connectors[0].ptr = connector;
+	state->connectors[0].old_state = conn_state;
+	state->connectors[0].new_state = conn_state;
+
+	return state;
+}
+
+/**
+ * dm_test_add_affected_mst_dsc_crtcs_writeback - Test writeback connectors are ignored
+ * @test: The KUnit test context
+ */
+static void dm_test_add_affected_mst_dsc_crtcs_writeback(struct kunit *test)
+{
+	struct amdgpu_dm_connector *aconnector;
+	struct drm_atomic_commit *state;
+	struct drm_crtc *crtc;
+
+	aconnector = kunit_kzalloc(test, sizeof(*aconnector), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, aconnector);
+	crtc = kunit_kzalloc(test, sizeof(*crtc), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, crtc);
+
+	aconnector->base.connector_type = DRM_MODE_CONNECTOR_WRITEBACK;
+	state = dm_test_state_with_connector(test, &aconnector->base, crtc);
+
+	KUNIT_EXPECT_EQ(test, add_affected_mst_dsc_crtcs(state, crtc), 0);
+}
+
+/**
+ * dm_test_add_affected_mst_dsc_crtcs_not_mst - Test a non-MST connector adds nothing
+ * @test: The KUnit test context
+ */
+static void dm_test_add_affected_mst_dsc_crtcs_not_mst(struct kunit *test)
+{
+	struct amdgpu_dm_connector *aconnector;
+	struct drm_atomic_commit *state;
+	struct drm_crtc *crtc;
+
+	aconnector = kunit_kzalloc(test, sizeof(*aconnector), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, aconnector);
+	crtc = kunit_kzalloc(test, sizeof(*crtc), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, crtc);
+
+	aconnector->base.connector_type = DRM_MODE_CONNECTOR_DisplayPort;
+	state = dm_test_state_with_connector(test, &aconnector->base, crtc);
+
+	KUNIT_EXPECT_EQ(test, add_affected_mst_dsc_crtcs(state, crtc), 0);
+}
+
+/**
+ * dm_test_add_affected_mst_dsc_crtcs_other_crtc - Test connectors on other CRTCs are skipped
+ * @test: The KUnit test context
+ */
+static void dm_test_add_affected_mst_dsc_crtcs_other_crtc(struct kunit *test)
+{
+	struct amdgpu_dm_connector *aconnector;
+	struct drm_atomic_commit *state;
+	struct drm_crtc *crtc, *other_crtc;
+
+	aconnector = kunit_kzalloc(test, sizeof(*aconnector), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, aconnector);
+	crtc = kunit_kzalloc(test, sizeof(*crtc), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, crtc);
+	other_crtc = kunit_kzalloc(test, sizeof(*other_crtc), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, other_crtc);
+
+	aconnector->base.connector_type = DRM_MODE_CONNECTOR_DisplayPort;
+	state = dm_test_state_with_connector(test, &aconnector->base, other_crtc);
+
+	KUNIT_EXPECT_EQ(test, add_affected_mst_dsc_crtcs(state, crtc), 0);
+}
+
+/**
+ * dm_test_add_affected_mst_dsc_crtcs_disabled - Test a disabled connector uses its old state
+ * @test: The KUnit test context
+ */
+static void dm_test_add_affected_mst_dsc_crtcs_disabled(struct kunit *test)
+{
+	struct amdgpu_dm_connector *aconnector;
+	struct drm_connector_state *new_conn_state;
+	struct drm_atomic_commit *state;
+	struct drm_crtc *crtc;
+
+	aconnector = kunit_kzalloc(test, sizeof(*aconnector), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, aconnector);
+	crtc = kunit_kzalloc(test, sizeof(*crtc), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, crtc);
+	new_conn_state = kunit_kzalloc(test, sizeof(*new_conn_state), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, new_conn_state);
+
+	aconnector->base.connector_type = DRM_MODE_CONNECTOR_DisplayPort;
+	state = dm_test_state_with_connector(test, &aconnector->base, crtc);
+	state->connectors[0].new_state = new_conn_state;
+
+	KUNIT_EXPECT_EQ(test, add_affected_mst_dsc_crtcs(state, crtc), 0);
+}
+
 static struct kunit_case amdgpu_dm_tests[] = {
 	/* Simple DM callbacks */
 	KUNIT_CASE(dm_test_wait_for_idle),
@@ -1355,6 +1491,12 @@ static struct kunit_case amdgpu_dm_tests[] = {
 	/* dm_atomic_get_state / dm_atomic_duplicate_state */
 	KUNIT_CASE(dm_test_atomic_get_state_already_acquired),
 	KUNIT_CASE(dm_test_atomic_duplicate_state_no_context),
+	/* add_affected_mst_dsc_crtcs */
+	KUNIT_CASE(dm_test_add_affected_mst_dsc_crtcs_no_connector),
+	KUNIT_CASE(dm_test_add_affected_mst_dsc_crtcs_writeback),
+	KUNIT_CASE(dm_test_add_affected_mst_dsc_crtcs_not_mst),
+	KUNIT_CASE(dm_test_add_affected_mst_dsc_crtcs_other_crtc),
+	KUNIT_CASE(dm_test_add_affected_mst_dsc_crtcs_disabled),
 	{}
 };
 
-- 
2.43.0