[U-Boot] [PATCH v2 4/4] kbuild: fix build rule of u-boot-spl.dtb

[Masahiro Yamada]

The build command of u-boot-spl.dtb is not constant, but dependent
on CONFIG_OF_SPL_REMOVE_PROPS.  Use $(call if_changed,...) so that
the change of CONFIG_OF_SPL_REMOVE_PROPS is detected.

Also, add tools/fdtgrep to the dependency to make sure u-boot-spl.dtb
is generated by the up-to-date fdtgrep in case the tool is modified.

Signed-off-by: Masahiro Yamada <yamada.masahiro at socionext.com>
---

Changes in v2:
  - add tools/fdtgrep to the dependency

 scripts/Makefile.spl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl
index d21c278..43df675 100644
--- a/scripts/Makefile.spl
+++ b/scripts/Makefile.spl
@@ -193,8 +193,8 @@ quiet_cmd_fdtgrep = FDTGREP $@
 	$(objtree)/tools/fdtgrep -r -O dtb - -o $@ \
 		$(addprefix -P ,$(subst $\",,$(CONFIG_OF_SPL_REMOVE_PROPS)))
 
-$(obj)/$(SPL_BIN).dtb: dts/dt.dtb
-	$(call cmd,fdtgrep)
+$(obj)/$(SPL_BIN).dtb: dts/dt.dtb $(objtree)/tools/fdtgrep FORCE
+	$(call if_changed,fdtgrep)
 
 quiet_cmd_cpp_cfg = CFG     $@
 cmd_cpp_cfg = $(CPP) -Wp,-MD,$(depfile) $(cpp_flags) $(LDPPFLAGS) -ansi \
-- 
1.9.1