diff --git a/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.c b/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.c
index c242b8d41b8a22e6ab6ad3eb0f492f3292c091e4..7c0eb52b91b87aa28e82c710c445fdd87216c1ac 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.c
+++ b/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.c
@@ -59,36 +59,3 @@ unsigned int dml_round_to_multiple(
 	else
 		return (num - remainder);
 }
-
-bool dml_util_is_420(enum source_format_class sorce_format)
-{
-	bool val = false;
-
-	switch (sorce_format) {
-	case dm_444_16:
-		val = false;
-		break;
-	case dm_444_32:
-		val = false;
-		break;
-	case dm_444_64:
-		val = false;
-		break;
-	case dm_420_8:
-		val = true;
-		break;
-	case dm_420_10:
-		val = true;
-		break;
-	case dm_422_8:
-		val = false;
-		break;
-	case dm_422_10:
-		val = false;
-		break;
-	default:
-		BREAK_TO_DEBUGGER();
-	}
-
-	return val;
-}
diff --git a/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.h b/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.h
index c621f8321b03a128e8a1a424dc7a6d2f268b36cf..a2da3da5ef8f05eeae0a891f787a20aaa33f19d4 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.h
+++ b/drivers/gpu/drm/amd/display/dc/dml/dml_common_defs.h
@@ -32,7 +32,6 @@
 
 #define DTRACE(str, ...) dm_logger_write(mode_lib->logger, LOG_DML, str, ##__VA_ARGS__);
 
-bool dml_util_is_420(enum source_format_class sorce_format);
 double dml_round(double a);
 unsigned int dml_round_to_multiple(
 			unsigned int num, unsigned int multiple, bool up);