drm: prefix header search paths with $(srctree)/

Currently, the Kbuild core manipulates header search paths in a crazy
way [1].

To fix this mess, I want all Makefiles to add explicit $(srctree)/ to
the search paths in the srctree. Some Makefiles are already written in
that way, but not all. The goal of this work is to make the notation
consistent, and finally get rid of the gross hacks.

Having whitespaces after -I does not matter since commit 48f6e3cf
("kbuild: do not drop -I without parameter").

[1]: https://patchwork.kernel.org/patch/9632347/Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1553859161-2628-1-git-send-email-yamada.masahiro@socionext.com

drivers/gpu/drm/amd/amdgpu/Makefile

@@ -23,7 +23,7 @@
 # Makefile for the drm device driver.  This driver provides support for the
 # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
 
-FULL_AMD_PATH=$(src)/..
+FULL_AMD_PATH=$(srctree)/$(src)/..
 DISPLAY_FOLDER_NAME=display
 FULL_AMD_DISPLAY_PATH = $(FULL_AMD_PATH)/$(DISPLAY_FOLDER_NAME)
 

drivers/gpu/drm/arm/display/komeda/Makefile

 # SPDX-License-Identifier: GPL-2.0
 
 ccflags-y := \
-	-I$(src)/../include \
-	-I$(src)
+	-I $(srctree)/$(src)/../include \
+	-I $(srctree)/$(src)
 
 komeda-y := \
 	komeda_drv.o \

drivers/gpu/drm/i915/gvt/Makefile

@@ -5,5 +5,5 @@ GVT_SOURCE := gvt.o aperture_gm.o handlers.o vgpu.o trace_points.o firmware.o \
 	execlist.o scheduler.o sched_policy.o mmio_context.o cmd_parser.o debugfs.o \
 	fb_decoder.o dmabuf.o page_track.o
 
-ccflags-y				+= -I$(src) -I$(src)/$(GVT_DIR)
+ccflags-y				+= -I $(srctree)/$(src) -I $(srctree)/$(src)/$(GVT_DIR)/
 i915-y					+= $(addprefix $(GVT_DIR)/, $(GVT_SOURCE))

drivers/gpu/drm/msm/Makefile

 # SPDX-License-Identifier: GPL-2.0
-ccflags-y := -Idrivers/gpu/drm/msm
-ccflags-y += -Idrivers/gpu/drm/msm/disp/dpu1
-ccflags-$(CONFIG_DRM_MSM_DSI) += -Idrivers/gpu/drm/msm/dsi
+ccflags-y := -I $(srctree)/$(src)
+ccflags-y += -I $(srctree)/$(src)/disp/dpu1
+ccflags-$(CONFIG_DRM_MSM_DSI) += -I $(srctree)/$(src)/dsi
 
 msm-y := \
 	adreno/adreno_device.o \

drivers/gpu/drm/nouveau/Kbuild

-ccflags-y += -I$(src)/include
-ccflags-y += -I$(src)/include/nvkm
-ccflags-y += -I$(src)/nvkm
-ccflags-y += -I$(src)
+ccflags-y += -I $(srctree)/$(src)/include
+ccflags-y += -I $(srctree)/$(src)/include/nvkm
+ccflags-y += -I $(srctree)/$(src)/nvkm
+ccflags-y += -I $(srctree)/$(src)
 
 # NVKM - HW resource manager
 #- code also used by various userspace tools/tests