[U-Boot] [PATCH 3/7] arm: use generic dtb rule with CONFIG_DEFAULT_DEVICE_TREE

[Thomas Chou <thomas@wytron.com.tw>]

Hi Simon,

On 2016?01?05? 08:56, Simon Glass wrote:
> One of the benefits of device tree is that we can run the same code
> paths on multiple boards. Then buildman has less work to do. For
> example, if it builds 'snow' then we know that 'pit' and 'pi' are good
> also. If you change the way device trees work then we lose this
> benefit. It would be great if we could build (say) 100 boards for 100%
> code coverage instead of 1000 boards.
>
> If you can find a way to build all the device tree files for a
> particular SoC without listing them out in the Makefile, then fine.
> But I really don't want to lose that feature. It is very useful.
>

I am preparing an update v2 to support building list of DT from configs.

By adding support of list to DEFAULT_DEVICE_TREE,
This option specifies a space-separated list of Device Tree used
for DT control.  Each DT in the list will be compiled. The first will be 
used as default to ship.

> Another example is sandbox, which builds both 'sandbox.dts' and
> 'test.dts'. It allows us to run a test easily:
>
> ./sandbox/u-boot -d sandbox/arch/sandbox/dts/test.dtb -c "ut dm
> usb_kdb" for example.
>
> If we didn't have that it would be a right pain to run tests.
>

No problem. The test.dtb rules is retained.

> I still don't understand what problem you are trying to solve. Can you
> explain again what is wrong with the status quo?

The current build generate too many DTB that users probably don't 
want/need. And the arch//dts/Makefile grows fat as every new 
board/target add lines to it. There should be some way to handle it in a 
cleaner style.

Best regards,
Thomas