Regression when building with DEVICE_TREE parameter

[Patrice CHOTARD]

Hi Masahiro

As indicated into doc/README.fdt-control, it's possible build U-boot with specifying dts-file-name using
$ make DEVICE_TREE=<dts-file-name>
But since your commit a3444bd09af9 ("Revert "Ensure device tree DTS is compiled") it's no more possible:

make ARCH=arm CROSS_COMPILE=$CROSS_COMPILE -j 16 DEVICE_TREE="trial"

Device Tree Source is not correctly specified.
Please define 'CONFIG_DEFAULT_DEVICE_TREE'
or build with 'DEVICE_TREE=<device_tree>' argument

dts/Makefile:28: recipe for target 'arch/arm/dts/trial.dtb' failed
make[1]: *** [arch/arm/dts/trial.dtb] Error 1
Makefile:1087: recipe for target 'dts/dt.dtb' failed
make: *** [dts/dt.dtb] Error 2

By reverting the above patch, it's restoring the attended behavior. But In your commit you indicated several issues.

Unfortunately, i am not a Makefile "expert", can anybody have a look at it ?

Thanks

Patrice