drm/amd/display: Test power module init

[WHAT]
Add KUnit tests for amdgpu_dm_init_power_module(), covering the skip
when no eDP is detected and the backlight parameter setup loop followed
by the allocation failure report.

[HOW]
mod_power_create() rejects a NULL DC, which walks the full parameter
setup loop without needing a live display core.

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>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

3 files changed, 43 insertions, 1 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 568ec421e65d..5ae59b3498b2 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -407,7 +407,7 @@ STATIC_IFN_KUNIT void mmhub_read_system_context(struct amdgpu_device *adev,
 }
 EXPORT_IF_KUNIT(mmhub_read_system_context);
 
-static int amdgpu_dm_init_power_module(struct amdgpu_display_manager *dm)
+STATIC_IFN_KUNIT int amdgpu_dm_init_power_module(struct amdgpu_display_manager *dm)
 {
 	struct mod_power_init_params init_data[MAX_NUM_EDP];
 
@@ -470,6 +470,7 @@ static int amdgpu_dm_init_power_module(struct amdgpu_display_manager *dm)
 
 	return 0;
 }
+EXPORT_IF_KUNIT(amdgpu_dm_init_power_module);
 
 static int amdgpu_dm_init(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 a53246040948..5e9d0b203a0f 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -1252,6 +1252,7 @@ struct dc_phy_addr_space_config;
 
 void mmhub_read_system_context(struct amdgpu_device *adev,
 			       struct dc_phy_addr_space_config *pa_config);
+int amdgpu_dm_init_power_module(struct amdgpu_display_manager *dm);
 #endif
 
 #endif /* __AMDGPU_DM_H__ */
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 bb52da037e69..d1a25b3e68c5 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
@@ -3522,6 +3522,43 @@ static void dm_test_mmhub_agp_enabled_renoir(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, pa_config.system_aperture.end_addr, 0x80000000ULL);
 }
 
+/* Tests for amdgpu_dm_init_power_module() */
+
+/**
+ * dm_test_init_power_module_no_edp - Test no eDP skips the power module
+ * @test: The KUnit test context
+ */
+static void dm_test_init_power_module_no_edp(struct kunit *test)
+{
+	struct amdgpu_device *adev = dm_kunit_alloc_adev(test);
+
+	adev->dm.ddev = &adev->ddev;
+	adev->dm.num_of_edps = 0;
+
+	KUNIT_EXPECT_EQ(test, amdgpu_dm_init_power_module(&adev->dm), 0);
+	KUNIT_EXPECT_NULL(test, adev->dm.power_module);
+}
+
+/**
+ * dm_test_init_power_module_alloc_failure - Test a failed power module create
+ * @test: The KUnit test context
+ *
+ * mod_power_create() rejects a NULL DC, which walks the full parameter setup
+ * loop and then reports the allocation failure.
+ */
+static void dm_test_init_power_module_alloc_failure(struct kunit *test)
+{
+	struct amdgpu_device *adev = dm_kunit_alloc_adev(test);
+
+	adev->dm.ddev = &adev->ddev;
+	adev->dm.num_of_edps = 1;
+	adev->dm.backlight_caps[0].min_input_signal = 0x10;
+	adev->dm.backlight_caps[0].max_input_signal = 0xff;
+
+	KUNIT_EXPECT_EQ(test, amdgpu_dm_init_power_module(&adev->dm), -ENOMEM);
+	KUNIT_EXPECT_NULL(test, adev->dm.power_module);
+}
+
 static struct kunit_case amdgpu_dm_tests[] = {
 	/* Simple DM callbacks */
 	KUNIT_CASE(dm_test_wait_for_idle),
@@ -3699,6 +3736,9 @@ static struct kunit_case amdgpu_dm_tests[] = {
 	KUNIT_CASE(dm_test_mmhub_agp_disabled_raven2),
 	KUNIT_CASE(dm_test_mmhub_agp_enabled),
 	KUNIT_CASE(dm_test_mmhub_agp_enabled_renoir),
+	/* amdgpu_dm_init_power_module */
+	KUNIT_CASE(dm_test_init_power_module_no_edp),
+	KUNIT_CASE(dm_test_init_power_module_alloc_failure),
 	{}
 };