marvell/linux/drivers/gpu/drm/i915/gem/Makefile - T108 - Gitiles

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

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

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