[PATCH 09/40] drm/amd/display: Test cached suspend state

[Ray Wu <ray.wu@amd.com>]

From: Alex Hung <alex.hung@amd.com>

[Why]
Add KUnit tests for dm_cache_state() covering successful caching
on an empty DRM device and propagation of an atomic suspend error.

[How]
Use the standard DRM KUnit device for the success path and the
shared DM ops table to inject the suspend failure.

Assisted-by: Copilot:Claude-Opus-5 GPT-5.6 Sol
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  5 ++-
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |  1 +
 .../display/amdgpu_dm/tests/amdgpu_dm_test.c  | 40 +++++++++++++++++++
 3 files changed, 44 insertions(+), 2 deletions(-)

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 9b1ffc04c761..42e2ef74c687 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1540,11 +1540,11 @@ STATIC_IFN_KUNIT enum dc_status amdgpu_dm_commit_zero_streams(struct dc *dc)
 }
 EXPORT_IF_KUNIT(amdgpu_dm_commit_zero_streams);
 
-static int dm_cache_state(struct amdgpu_device *adev)
+STATIC_IFN_KUNIT int dm_cache_state(struct amdgpu_device *adev)
 {
 	int r;
 
-	adev->dm.cached_state = drm_atomic_helper_suspend(adev_to_drm(adev));
+	adev->dm.cached_state = dm_atomic_helper_suspend(adev_to_drm(adev));
 	if (IS_ERR(adev->dm.cached_state)) {
 		r = PTR_ERR(adev->dm.cached_state);
 		adev->dm.cached_state = NULL;
@@ -1552,6 +1552,7 @@ static int dm_cache_state(struct amdgpu_device *adev)
 
 	return adev->dm.cached_state ? 0 : r;
 }
+EXPORT_IF_KUNIT(dm_cache_state);
 
 STATIC_IFN_KUNIT void dm_destroy_cached_state(struct amdgpu_device *adev)
 {
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 739171d5365c..4d12632d048f 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -1276,6 +1276,7 @@ void mmhub_read_system_context(struct amdgpu_device *adev,
 int amdgpu_dm_init_power_module(struct amdgpu_display_manager *dm);
 void dm_gpureset_toggle_interrupts(struct amdgpu_device *adev, struct dc_state *state, bool enable);
 enum dc_status amdgpu_dm_commit_zero_streams(struct dc *dc);
+int dm_cache_state(struct amdgpu_device *adev);
 void dm_destroy_cached_state(struct amdgpu_device *adev);
 int dm_early_init(struct amdgpu_ip_block *ip_block);
 int fill_dc_plane_info_and_addr(struct amdgpu_device *adev,
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 833f73972ab2..61fa553c7a99 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
@@ -4371,6 +4371,44 @@ static void dm_test_commit_zero_streams_empty(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, (int)amdgpu_dm_commit_zero_streams(dc), (int)DC_OK);
 }
 
+/**
+ * dm_test_cache_state_empty_device - Test caching an empty DRM atomic state
+ * @test: The KUnit test context
+ */
+static void dm_test_cache_state_empty_device(struct kunit *test)
+{
+	struct amdgpu_device *adev = dm_kunit_alloc_adev(test);
+
+	KUNIT_ASSERT_EQ(test, dm_cache_state(adev), 0);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, adev->dm.cached_state);
+
+	dm_destroy_cached_state(adev);
+	KUNIT_EXPECT_NULL(test, adev->dm.cached_state);
+}
+
+static struct drm_atomic_commit *dm_test_atomic_helper_suspend_error(struct drm_device *dev)
+{
+	return ERR_PTR(-EIO);
+}
+
+static const struct amdgpu_dm_kunit_ops dm_test_cache_state_ops = {
+	.atomic_helper_suspend = dm_test_atomic_helper_suspend_error,
+};
+
+/**
+ * dm_test_cache_state_error - Test atomic suspend errors are returned and cleared
+ * @test: The KUnit test context
+ */
+static void dm_test_cache_state_error(struct kunit *test)
+{
+	struct amdgpu_device *adev = dm_kunit_alloc_adev(test);
+
+	dm_test_install_dm_ops(test, &dm_test_cache_state_ops);
+
+	KUNIT_EXPECT_EQ(test, dm_cache_state(adev), -EIO);
+	KUNIT_EXPECT_NULL(test, adev->dm.cached_state);
+}
+
 /**
  * dm_test_destroy_cached_state_none - Test no cached state is a no-op
  * @test: The KUnit test context
@@ -5196,6 +5234,8 @@ static struct kunit_case amdgpu_dm_tests[] = {
 	KUNIT_CASE(dm_test_early_init_unsupported_version),
 	/* suspend and resume helpers */
 	KUNIT_CASE(dm_test_commit_zero_streams_empty),
+	KUNIT_CASE(dm_test_cache_state_empty_device),
+	KUNIT_CASE(dm_test_cache_state_error),
 	KUNIT_CASE(dm_test_destroy_cached_state_none),
 	/* dm_update_mst_vcpi_slots_for_dsc */
 	KUNIT_CASE(dm_test_mst_vcpi_slots_no_connector),
-- 
2.43.0