diff --git a/drivers/base/regmap/regmap-mmio.c b/drivers/base/regmap/regmap-mmio.c
index 7526906ca080..1aa26aa31f6a 100644
--- a/drivers/base/regmap/regmap-mmio.c
+++ b/drivers/base/regmap/regmap-mmio.c
@@ -212,6 +212,7 @@ static const struct regmap_bus regmap_mmio = {
 	.reg_write = regmap_mmio_write,
 	.reg_read = regmap_mmio_read,
 	.free_context = regmap_mmio_free_context,
+	.val_format_endian_default = REGMAP_ENDIAN_LITTLE,
 };
 
 static struct regmap_mmio_context *regmap_mmio_gen_context(struct device *dev,