[U-Boot] [PATCH v5 10/13] tegra: Use a U-Boot-specific .dtsi file

[Simon Glass]

Hi Stephen,

On 2 December 2016 at 12:19, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 11/30/2016 07:19 PM, Simon Glass wrote:
>>
>> Hi Stephen,
>>
>> On 29 November 2016 at 21:09, Stephen Warren <swarren at wwwdotorg.org>
>> wrote:
>>>
>>> On 11/28/2016 03:09 PM, Simon Glass wrote:
>>>>
>>>>
>>>> Hi Stephen,
>>>>
>>>> On 17 November 2016 at 12:45, Stephen Warren <swarren at wwwdotorg.org>
>>>> wrote:
>>>>>
>>>>>
>>>>>
>>>>> On 11/16/2016 06:13 PM, Simon Glass wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> With the new device-tree rules it is possible to put device-tree
>>>>>> changes
>>>>>> needed by U-Boot into their own file. As an example of this approach,
>>>>>> move
>>>>>> Tegra over to use it.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Sounds like a good idea.
>>>>>
>>>>>> diff --git a/arch/arm/dts/tegra20-u-boot.dtsi
>>>>>> b/arch/arm/dts/tegra20-u-boot.dtsi
>>>
>>>
>>>
>>>>> I'd expect to see more "U-Boot overlay" DTs than this; I recall there
>>>>> being more differences between U-Boot and kernel DTS files when I last
>>>>> sync'd the two.
>>>>
>>>>
>>>>
>>>> Yes but most of those changes should be dropped. I did a partial sync
>>>> a few months back but if you recall there were still differences. Is
>>>> this something the Tegra maintainer might look at?
>>>>
>>>> I don't want to immortalise those differences in a separate U-Boot
>>>> file when really we should just get rid of them.
>>>
>>>
>>>
>>> From my perspective, we should have two files:
>>>
>>> 1) The base DT.
>>>
>>> This should not contain any U-Boot modifications, and should exactly
>>> match
>>> the DT used elsewhere, such as in mainline Linux. Since this should
>>> always
>>> match other DTs, we should pretty much always be able to over-write it
>>> with
>>> any updated DT from other sources.
>>>
>>> 2) The U-Boot modifications.
>>>
>>> This always contain /all/ local modifications applied by U-Boot. It
>>> shouldn't matter why the change was made, or how long we hope/expect the
>>> delta to continue to exist. This will isolate all U-Boot changes into
>>> this
>>> file so it's obvious what local changes exist. If some changes are
>>> intended
>>> to be temporary, we can add a comment to that effect, and eventually
>>> submit
>>> a patch to remove the delta.
>>>
>>> I don't think that putting a change into this "U-Boot local overlay"
>>> should
>>> in any way imply that the change is by definition correct and long-term;
>>> some changes may satisfy that decription and others won't. Just like we
>>> sometimes have C code that we wish we didn't and eventually clean up.
>>
>>
>> That's fine with me. What do you want to do with this patch?
>
>
> IIRC the patch content is fine as far as it goes, but it'd be nice to take
> it all the way and move all the U-Boot diffs into
> arch/arm/dts/tegra20-u-boot.dtsi if possible.

OK, can you please add a review or test tag?

I will see if I can take a look in January. Is there any chance that
Nvidia might put some effort into this?

Regards,
Simon