Re: [PATCH v3 1/3] dt-bindings: interconnect: Remove required reg field
From: Krzysztof Kozlowski
Date: Mon Nov 07 2022 - 13:28:47 EST
On 07/11/2022 15:36, Georgi Djakov wrote:
> Hi,
>
> On 2.11.22 23:11, Krzysztof Kozlowski wrote:
>> On 31/10/2022 19:29, Melody Olvera wrote:
>>>
>>>
>>> On 10/27/2022 8:29 AM, Krzysztof Kozlowski wrote:
>>>> On 26/10/2022 15:05, Melody Olvera wrote:
>>>>> Many of the *-virt compatible devices do not have a reg field
>>>>> so remove it as required from the bindings.
>>>> and some virt have it... This should be probably separate binding or if
>>>> the list is small - allOf:if:then.
>>> I attempted this; however I'm still seeing failures in dtb_check. I've added this
>>> to the binding; does this look correct?
>>> allOf:
>>> - $ref: qcom,rpmh-common.yaml#
>>> + - if:
>>> + properties:
>>> + compatible:
>>> + contains:
>>> + enum:
>>> + - qcom,qdu1000-clk-virt
>>> + - qcom,qdu1000-mc-virt
>>> +
>>> + then:
>>> + required:
>>> + - compatible
>>
>> No, because we talk about reg, not compatible. You should not require
>> reg instead for some compatibles... but then the schema is getting
>> complicated.
>>
>> It's difficult to give you recommendation because I do not know what are
>> all these "virt" interconnects. Why some have unit address, why some do not?
>
> My understanding is that the "reg" property is required for the NoCs that have
> registers for controlling the QoS settings for the ports from Linux side.
> Other NoCs might be controlled by some remote processor and direct access from
> Linux may not be possible, so they do not have unit address and are outside of
> the soc DT node.
> Do we need to strictly define when exactly the "reg" property is required,
> can't we just mark it as optional?
It's preferred to make it strictly required or not allowed, so the
bindings are specific. This also allows to validate for mistakes. It
would be a bit different case if such test for req would make the
bindings complicated. I think it's not the case because we could just
split the bindings into two files:
1. One for controlled by AP, with reg.
2. One for controller by remote processors, without reg.
Best regards,
Krzysztof