Re: [PATCH v4 2/4] dt-bindings: interrupt-controller: sifive,plic: add legacy riscv compatible

[<Conor.Dooley@microchip.com>]

On 24/08/2022 18:44, Heiko Stübner wrote:
> Am Dienstag, 23. August 2022, 20:33:18 CEST schrieb Conor Dooley:
>> From: Conor Dooley <conor.dooley@microchip.com>
>>
>> While "real" hardware might not use the compatible string "riscv,plic0"
>> it is present in the driver & QEMU uses it for automatically generated
>> virt machine dtbs. To avoid dt-validate problems with QEMU produced
>> dtbs, such as the following, add it to the binding.
>>
>> riscv-virt.dtb: plic@c000000: compatible: 'oneOf' conditional failed, one must be fixed:
>>         'sifive,plic-1.0.0' is not one of ['sifive,fu540-c000-plic', 'starfive,jh7100-plic', 'canaan,k210-plic']
>>         'sifive,plic-1.0.0' is not one of ['allwinner,sun20i-d1-plic']
>>         'sifive,plic-1.0.0' was expected
>>         'thead,c900-plic' was expected
>> riscv-virt.dtb: plic@c000000: '#address-cells' is a required property
>>
>> Reported-by: Rob Herring <robh@kernel.org>
>> Link: https://lore.kernel.org/linux-riscv/20220803170552.GA2250266-robh@kernel.org/
>> Reviewed-by: Rob Herring <robh@kernel.org>
>> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
>> ---
>>  .../bindings/interrupt-controller/sifive,plic-1.0.0.yaml     | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml
>> index 92e0f8c3eff2..99e01f4d0a69 100644
>> --- a/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml
>> +++ b/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml
>> @@ -66,6 +66,11 @@ properties:
>>            - enum:
>>                - allwinner,sun20i-d1-plic
>>            - const: thead,c900-plic
>> +      - items:
>> +          - const: sifive,plic-1.0.0
>> +          - const: riscv,plic0
>> +        deprecated: true
> 
> hmm, when setting this to deprecated, does this mean qemu was changed
> to not use that compatible anymore?
> 
> I.e. reading deprecated I'd assume that this is kept around for old qemu builds?

I did not make that change to QEMU. From v1 [0]:

Rob:
> Conor:
>> In arm's virt.c they use the generic gic compatible & I don't see any
>> evidence of other archs using "qemu,foo" bindings. I suppose there's
>> always the option of just removing the "riscv,plic0" from the riscv's
>> virt.c
>
> I think we're pretty much stuck with what's in use already.

> I'm on the fence whether to mark it deprecated though if there is no 
> plan to 'fix' it. Doesn't really matter until the tools can selectively 
> remove deprecated properties from validation.

My interpretation was "do not use this compatible in any new devicetrees".

I don't really have any strong feelings here. Maybe the description is
sufficient?

Thanks,
Conor,

0 - https://lore.kernel.org/linux-riscv/20220809141436.GA1706120-robh@kernel.org/
> 
>> +        description: For the QEMU virt machine only
>>  
>>    reg:
>>      maxItems: 1
>>
> 
> 
> 
>