drivers/gpu/drm/i915/display/Makefile - linux - Git at Google

 # For building individual subdir files on the command line
 subdir-ccflags-y += -I$(srctree)/$(src)/..

 # Extra header tests
 header-test-pattern-$(CONFIG_DRM_I915_WERROR) := *.h
 header-test- := intel_vbt_defs.h
	# For building individual subdir files on the command line
	subdir-ccflags-y += -I$(srctree)/$(src)/..

	# Extra header tests
	header-test-pattern-$(CONFIG_DRM_I915_WERROR) := *.h
	header-test- := intel_vbt_defs.h