We get 2 warnings about global functions without a declaration in the ASoC mediatek module when building with W=1: sound/soc/mediatek/common/mtk-afe-fe-dai.c:26:5: warning: no previous prototype for 'mtk_regmap_update_bits' [-Wmissing-prototypes] int mtk_regmap_update_bits(struct regmap *map, int reg, unsigned int mask, ^ sound/soc/mediatek/common/mtk-afe-fe-dai.c:34:5: warning: no previous prototype for 'mtk_regmap_write' [-Wmissing-prototypes] int mtk_regmap_write(struct regmap *map, int reg, unsigned int val) In fact, all of those functions are only used in the file in which they are declared and don't need a declaration, but can be made static. so this patch marks it 'static'. Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org> Signed-off-by: Mark Brown <broonie@kernel.org>