[U-Boot] dtoverlay for mx6 ARM

[Michal Suchanek]

Hello,

On 12 June 2015 at 00:14, Johann Obermayr <johann.obermayr at sigmatek.at> wrote:
> Am 11.06.2015 um 22:13 schrieb Jakub Kiciński:
>>
>> On Thu, 11 Jun 2015 21:49:57 +0200, Johann Obermayr wrote:
>>>
>>> Hello,
>>
>> Hi there,
>>
>>>
>>> for raspberyy pi there are some "features" available.
>>> dtoverlay, dtparam, ...
>>> we have a Freescale mx6 CPU.
>>> How we can add/enable this features ?
>>
>> I'm new to U-Boot but on RPi the "features" are provided by their
>> proprietary firmware/bootloader.   AFAIK U-Boot doesn't support DT
>> overlays.
>>
>> Kuba
>>
> Thank you for this information.
>
> Is there a way to change a loaded devicetree configuration ?
>
> Because we have many boards with small differents. but less memory on disk.
> at this time one DTB file need ~150kb. we have 1MB free, but we have > 20
> different boards and
> every month 1 or 2 new boards.

This depends on the changes you want.

If the change is in a part of the DT which you do not need to boot you
can just leave that part out and build overlay bits which you load at
runtime in your init scripts (needs kernel and dtc patches).

If the changes are required to boot there is some support in u-boot to
modify DTs but I am not sure how much functionality is desirable and
already implemented. Currently simplefb depends on u-boot modifying
pre-made DT nodes.

Thanks

Michal