diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
index 7e95232e93fe..538f14600c98 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.c
@@ -34,6 +34,7 @@
 #include "dal_asic_id.h"
 #include "amdgpu_display.h"
 #include "amdgpu_dm_trace.h"
+#include "amdgpu_dm_plane.h"
 #include "gc/gc_11_0_0_offset.h"
 #include "gc/gc_11_0_0_sh_mask.h"
 
@@ -149,12 +150,12 @@ static void add_modifier(uint64_t **mods, uint64_t *size, uint64_t *cap, uint64_
 	*size += 1;
 }
 
-bool modifier_has_dcc(uint64_t modifier)
+static bool modifier_has_dcc(uint64_t modifier)
 {
 	return IS_AMD_FMT_MOD(modifier) && AMD_FMT_MOD_GET(DCC, modifier);
 }
 
-unsigned modifier_gfx9_swizzle_mode(uint64_t modifier)
+static unsigned modifier_gfx9_swizzle_mode(uint64_t modifier)
 {
 	if (modifier == DRM_FORMAT_MOD_LINEAR)
 		return 0;
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h
index 95168c2cfa6f..286981a2dd40 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_plane.h
@@ -36,17 +36,9 @@ int fill_dc_scaling_info(struct amdgpu_device *adev,
 			 const struct drm_plane_state *state,
 			 struct dc_scaling_info *scaling_info);
 
-void get_min_max_dc_plane_scaling(struct drm_device *dev,
-				  struct drm_framebuffer *fb,
-				  int *min_downscale, int *max_upscale);
-
 int dm_plane_helper_check_state(struct drm_plane_state *state,
 				struct drm_crtc_state *new_crtc_state);
 
-bool modifier_has_dcc(uint64_t modifier);
-
-unsigned int modifier_gfx9_swizzle_mode(uint64_t modifier);
-
 int fill_plane_buffer_attributes(struct amdgpu_device *adev,
 				 const struct amdgpu_framebuffer *afb,
 				 const enum surface_pixel_format format,