[PATCH 1/2] Makefile: Add environment variable DEVICE_TREE to header

[Michal Simek]

On 26. 02. 20 16:33, Simon Glass wrote:
> Hi Michal,
> 
> On Tue, 18 Feb 2020 at 09:02, Michal Simek <michal.simek at xilinx.com> wrote:
>>
>> Users have option to overwrite default device tree
>> (CONFIG_DEFAULT_DEVICE_TREE) via environment variable DEVICE_TREE.
>>
>> Feature has been added long time ago by commit 74de8c9a1672
>> ("dts/Makefile: Build the user specified dts") for a little bit different
>> reason.
>>
>> But this variable can be also used for different purpose like choosing
>> proper configuration from FIT image in SPL.
>> And this is the functionality I would like to use on Xilinx Zynq devices
>> that current u-boot.img can be composed in the same way based on OF_LIST
>> and different configuration is taken based on platform specific SPL.
>> SPL requires low level ps7_init_gpl configuration that's why different
>> boards require different SPL with fixed board_fit_config_name_match().
>>
>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>> ---
>>
>> I have done it in this way but maybe there is any smarter way how this can
>> be done. Also macro name can change if you want.
> 
> Can you please add a bit of documentation to doc/README.fdt-control ?

This feature is cover by documentation in this file already. What
exactly do you think that should be added?

Thanks,
Michal

169 Build:
170
171 After board configuration is done, fdt supported u-boot can be build
in two ways:
172 1)  build the default dts which is defined from
CONFIG_DEFAULT_DEVICE_TREE
173     $ make
174 2)  build the user specified dts file
175     $ make DEVICE_TREE=<dts-file-name>
176
177