[PATCH 2/2] kbuild: handle dtb-y and CONFIG_OF_ALL_DTBS natively in Makefile.lib

[Arnd Bergmann]

On Sun, Nov 5, 2017 at 6:30 AM, Masahiro Yamada
<yamada.masahiro at socionext.com> wrote:
> If CONFIG_OF_ALL_DTBS is enabled, "make ARCH=arm64 dtbs" compiles each
> DTB twice; one from arch/arm64/boot/dts/*/Makefile and the other from
> the dtb-$(CONFIG_OF_ALL_DTBS) line in arch/arm64/boot/dts/Makefile.
> It could be a race problem when building DTBS in parallel.
>
> Another minor issue is CONFIG_OF_ALL_DTBS covers only *.dts in vendor
> sub-directories, so this broke when Broadcom added one more hierarchy
> in arch/arm64/boot/dts/broadcom/<soc>/.
>
> One idea to fix the issues in a clean way is to move DTB handling
> to Kbuild core scripts.  Makefile.dtbinst already recognizes dtb-y
> natively, so it should not hurt to do so.
>
> Add $(dtb-y) to extra-y, and $(dtb-) as well if CONFIG_OF_ALL_DTBS is
> enabled.  All clutter things in Makefiles go away.
>
> As a bonus clean-up, I also removed dts-dirs.  Just use subdir-y
> directly to traverse sub-directories.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>

Nice, that's much better than the hack I had.

Acked-by: Arnd Bergmann <arnd at arndb.de>