On Wed, Sep 5, 2018 at 3:36 PM Frank Rowand [off-list ref] wrote:

On 09/04/18 01:05, Tero Kristo wrote:

quoted

Currently the makefile is setup in such manner that even if
we build a DT file in a subdirectory under arch/arm/boot/dts,
it gets built based on the base boot/dts/Makefile rules.
This patch modifies the base makefile in such manner, that
it detects which makefile to use based on build target path.
This allows setting for example per-directory DTC_FLAGS and
using those for the subdir build. The dtbdir local variable
is setup to target to the build path.

Signed-off-by: Tero Kristo <redacted>
---
 arch/arm/Makefile | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index ab555a0..b7c21e8 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile

@@ -339,8 +339,10 @@ $(BOOT_TARGETS): vmlinux
 $(INSTALL_TARGETS):
      $(Q)$(MAKE) $(build)=$(boot) MACHINE=$(MACHINE) $@

+%.dtb %.dtbo: dtbdir = $(patsubst %/,%,$(patsubst %./,%,$(boot)/dts/$(dir $@)))
+
 %.dtb %.dtbo: | scripts
-     $(Q)$(MAKE) $(build)=$(boot)/dts MACHINE=$(MACHINE) $(boot)/dts/$@
+     $(Q)$(MAKE) $(build)=$(dtbdir) MACHINE=$(MACHINE) $(boot)/dts/$@

 PHONY += dtbs dtbs_install

The makefile magic to handle subdirectories below $(boot)/dts/ already
works properly to have Makefiles in $(boot)/dts/, using the following
rule in arch/arm64/Makefile:

%.dtb: scripts
        $(Q)$(MAKE) $(build)=$(boot)/dts $(boot)/dts/$@

I don't understand why that works for arm64, but it should work the
same way for arm.  Or if arch/arm is missing another piece from
arch/arm64 we should be consistent with however the make system
specifies it in arch/arm64

It should just need a subdir-y for the sub-directory. The target is
"subdir/some.dtb" though.

If we want to build specific directories, we should get the standard
way of doing that to work: make arch/arm/boot/dts/subdir/

Rob