Please define CONFIG_ARCH_DEVICE_TREE))
# We preprocess the device tree file provide a useful define
-DTS_CPPFLAGS := -ansi \
+DTS_CPPFLAGS := -x assembler-with-cpp \
-DARCH_CPU_DTS=\"$(SRCTREE)/arch/$(ARCH)/dts/$(CONFIG_ARCH_DEVICE_TREE).dtsi\" \
-DBOARD_DTS=\"$(SRCTREE)/board/$(VENDOR)/$(BOARD)/dts/$(DEVICE_TREE).dts\"