Re: [PATCH] of: unittest: Statically apply overlays using fdtoverlay

[Frank Rowand]

On 1/11/21 9:46 AM, Rob Herring wrote:
> On Fri, Jan 8, 2021 at 2:41 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
>>
>> Now that fdtoverlay is part of the kernel build, start using it to test
>> the unitest overlays we have by applying them statically.
> 
> Nice idea.
> 
>> The file overlay_base.dtb have symbols of its own and we need to apply
>> overlay.dtb to overlay_base.dtb alone first to make it work, which gives
>> us intermediate-overlay.dtb file.
> 
> Okay? If restructuring things helps we should do that. Frank?

I'm a little slow responding to this thread.  After seeing this question, I
responded to the patch email with a NACK (with further explanation in that
response).

-Frank

> 
>> The intermediate-overlay.dtb file along with all other overlays is them
> 
> s/them/then/
> 
>> applied to testcases.dtb to generate the master.dtb file.
>>
>> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
>>
>> ---
>> Depends on:
>>
>> https://lore.kernel.org/lkml/be5cb12a68d9ac2c35ad9dd50d6b168f7cad6837.1609996381.git.viresh.kumar@xxxxxxxxxx/
>>
>> I have kept the .dtb naming for overlays for now, lets see how we do it
>> eventually.
>>
>> Rob/Frank, this doesn't work properly right now. Maybe I missed how
>> these overlays must be applied or there is a bug in fdtoverlay.
>>
>> The master.dtb doesn't include any nodes from overlay_base.dtb or
>> overlay.dtb probably because 'testcase-data-2' node isn't present in
>> testcases.dtb and fdtoverlay doesn't allow applying new nodes to the
>> root node, i.e. allows new sub-nodes once it gets phandle to the parent
>> but nothing can be added to the root node itself. Though I get a feel
>> that it works while applying the nodes dynamically and it is expected to
>> work here as well.
> 
> Sounds like a bug in fdtoverlay to me. Though maybe you need an empty
> base tree. An overlay serving as the base is a bit odd so it's
> somewhat understandable fdtoverlay couldn't handle that. OTOH,
> combining 2 overlays together seems like a valid use.
> 
>>
>> (And yeah, this is my first serious attempt at updating Makefiles, I am
>> sure there is a scope of improvement here :))
> 
> Usually I write something and Masahiro rewrites it for me. :)
> 
> Rob
>