Re: [RFC PATCH 2/4] dt-bindings: firmware: thead,th1520-aon: add a mailbox name for SBI

[Krzysztof Kozlowski <krzk@kernel.org>]

On 14/08/2025 09:30, Icenowy Zheng wrote:
> 在 2025-08-14星期四的 09:18 +0200，Krzysztof Kozlowski写道：
>> On 14/08/2025 09:07, Icenowy Zheng wrote:
>>> The SBI firmware might want to communicate to the AON firmware too.
>>>
>>> Add a mbox-name item to allow to allocate a mailbox for SBI.
>>>
>>> Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
>>> ---
>>>  .../devicetree/bindings/firmware/thead,th1520-aon.yaml     | 7
>>> ++++---
>>>  1 file changed, 4 insertions(+), 3 deletions(-)
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/firmware/thead,th1520-aon.yaml
>>> b/Documentation/devicetree/bindings/firmware/thead,th1520-aon.yaml
>>> index 3365124c7fd47..555465f4aab4e 100644
>>> --- a/Documentation/devicetree/bindings/firmware/thead,th1520-
>>> aon.yaml
>>> +++ b/Documentation/devicetree/bindings/firmware/thead,th1520-
>>> aon.yaml
>>> @@ -26,11 +26,12 @@ properties:
>>>      const: thead,th1520-aon
>>>  
>>>    mboxes:
>>> -    maxItems: 1
>>> +    maxItems: 2
>>
>>
>> ABI break without explanation why ("allow" is not a reason to affect
>> ABI) and its impact.
> 
> Is adding items an ABI break?

Adding required items is ABI break. You can easily test it. Apply patch
#1 and test your DTS. Apply patch #2 and test your DTS. New warnings
appear, so that's a proof of ABI impact.


> 
> Or should I explicitly say "minItems: 1" here?

Yes, but you should clearly explain the impact. Is it working? Not
working? Are you fixing something?

Best regards,
Krzysztof