drm/amd/display: Test backlight device registration

[WHAT]
Add KUnit test to amdgpu_dm_register_backlight_device() and
cover its bl_idx == -1 early return, which must leave the
backlight device slot untouched.

Assisted-by: Copilot:Claude-Opus-4.8
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: George Zhang <george.zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c
index 452e772..859cbce 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_backlight.c
@@ -494,6 +494,7 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector)
                drm_dbg_driver(drm, "DM: Registered Backlight device: %s\n", bl_name);
        }
 }
+EXPORT_IF_KUNIT(amdgpu_dm_register_backlight_device);
 
 void amdgpu_dm_update_connector_ext_caps(struct amdgpu_dm_connector *aconnector)
 {

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_backlight_test.c b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_backlight_test.c
index 1096530..5a2c32d 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_backlight_test.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/tests/amdgpu_dm_backlight_test.c
@@ -440,6 +440,24 @@ static void dm_test_backlight_get_brightness_uses_device_index(struct kunit *tes
        KUNIT_EXPECT_EQ(test, amdgpu_dm_backlight_get_brightness(bd), 2468);
 }
 
+/* Tests for amdgpu_dm_register_backlight_device() */
+
+/**
+ * dm_test_register_backlight_device_negative_index - Test invalid index no-op
+ * @test: The KUnit test context
+ */
+static void dm_test_register_backlight_device_negative_index(struct kunit *test)
+{
+       struct amdgpu_device *adev = dm_kunit_alloc_adev(test);
+       struct amdgpu_dm_connector *aconnector;
+
+       aconnector = dm_kunit_alloc_connector(test, adev, NULL);
+       aconnector->bl_idx = -1;
+
+       amdgpu_dm_register_backlight_device(aconnector);
+       KUNIT_EXPECT_NULL(test, adev->dm.backlight_dev[0]);
+}
+
 /* Tests for amdgpu_dm_backlight_get_device_index() */
 
 /**
@@ -1616,6 +1634,8 @@ static struct kunit_case dm_backlight_test_cases[] = {
        KUNIT_CASE(dm_test_backlight_get_level_aux_success),
        KUNIT_CASE(dm_test_backlight_get_level_aux_error),
        KUNIT_CASE(dm_test_backlight_get_brightness_uses_device_index),
+       /* amdgpu_dm_register_backlight_device */
+       KUNIT_CASE(dm_test_register_backlight_device_negative_index),
        /* amdgpu_dm_backlight_get_device_index */
        KUNIT_CASE(dm_test_backlight_device_index_matches_second),
        KUNIT_CASE(dm_test_backlight_device_index_missing_fallback),