[PATCH AUTOSEL 4.20 11/60] sh: fix build error for invisible CONFIG_BUILTIN_DTB_SOURCE

[Sasha Levin]

From: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>

[ Upstream commit 207a369e3c085799e7836221f64e7a7329985fb6 ]

I fixed a similar build error in commit 1b1e4ee86e00 ("sh: fix build
error for empty CONFIG_BUILTIN_DTB_SOURCE"), but it came back again.

Since commit 37c8a5fafa3b ("kbuild: consolidate Devicetree dtb
build rules"), the combination of CONFIG_OF_EARLY_FLATTREE=y and
CONFIG_USE_BUILTIN_DTB=n results in the following build error:

  make[1]: *** No rule to make target 'arch/sh/boot/dts/.dtb.o',
  needed by 'arch/sh/boot/dts/built-in.a'.  Stop.

Prior to that commit, there was only one path to descend into
arch/sh/boot/dts/, and arch/sh/Makefile correctly guards it with
CONFIG_USE_BUILTIN_DTB:

  core-$(CONFIG_USE_BUILTIN_DTB)  += arch/sh/boot/dts/

Now, there is another path to descend there from the top Makefile
when CONFIG_OF_EARLY_FLATTREE=y. If CONFIG_USE_BUILTIN_DTB is disabled,
CONFIG_BUILTIN_DTB_SOURCE is invisible instead of defined as "".

Add obj-$(CONFIG_USE_BUILTIN_DTB) guard to avoid the attempt to build
the non-existing file.

Fixes: 37c8a5fafa3b ("kbuild: consolidate Devicetree dtb build rules")
Reported-by: kbuild test robot <lkp@xxxxxxxxx>
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 arch/sh/boot/dts/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sh/boot/dts/Makefile b/arch/sh/boot/dts/Makefile
index 01d0f7fb14cc..2563d1e532e2 100644
--- a/arch/sh/boot/dts/Makefile
+++ b/arch/sh/boot/dts/Makefile
@@ -1,3 +1,3 @@
 ifneq ($(CONFIG_BUILTIN_DTB_SOURCE),"")
-obj-y += $(patsubst "%",%,$(CONFIG_BUILTIN_DTB_SOURCE)).dtb.o
+obj-$(CONFIG_USE_BUILTIN_DTB) += $(patsubst "%",%,$(CONFIG_BUILTIN_DTB_SOURCE)).dtb.o
 endif
-- 
2.19.1