diff --git a/drivers/gpu/drm/vc4/tests/vc4_mock.h b/drivers/gpu/drm/vc4/tests/vc4_mock.h
index 002b6218960c..8b150a065e1c 100644
--- a/drivers/gpu/drm/vc4/tests/vc4_mock.h
+++ b/drivers/gpu/drm/vc4/tests/vc4_mock.h
@@ -7,9 +7,9 @@
 
 static inline
 struct drm_crtc *vc4_find_crtc_for_encoder(struct kunit *test,
-					   struct drm_device *drm,
 					   struct drm_encoder *encoder)
 {
+	struct drm_device *drm = encoder->dev;
 	struct drm_crtc *crtc;
 
 	KUNIT_ASSERT_EQ(test, hweight32(encoder->possible_crtcs), 1);
diff --git a/drivers/gpu/drm/vc4/tests/vc4_mock_output.c b/drivers/gpu/drm/vc4/tests/vc4_mock_output.c
index 577d9a956369..ff2168895749 100644
--- a/drivers/gpu/drm/vc4/tests/vc4_mock_output.c
+++ b/drivers/gpu/drm/vc4/tests/vc4_mock_output.c
@@ -91,7 +91,7 @@ int vc4_mock_atomic_add_output(struct kunit *test,
 	if (!encoder)
 		return -ENODEV;
 
-	crtc = vc4_find_crtc_for_encoder(test, drm, encoder);
+	crtc = vc4_find_crtc_for_encoder(test, encoder);
 	if (!crtc)
 		return -ENODEV;
 
@@ -148,7 +148,7 @@ int vc4_mock_atomic_del_output(struct kunit *test,
 	if (!encoder)
 		return -ENODEV;
 
-	crtc = vc4_find_crtc_for_encoder(test, drm, encoder);
+	crtc = vc4_find_crtc_for_encoder(test, encoder);
 	if (!crtc)
 		return -ENODEV;
 
diff --git a/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c b/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c
index d1f694029169..cfcab3dc392e 100644
--- a/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c
+++ b/drivers/gpu/drm/vc4/tests/vc4_test_pv_muxing.c
@@ -130,7 +130,7 @@ get_vc4_crtc_state_for_encoder(struct kunit *test,
 	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);
+	crtc = vc4_find_crtc_for_encoder(test, encoder);
 	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc);
 
 	new_crtc_state = drm_atomic_get_new_crtc_state(state, crtc);