Message-ID: <0f5f367e-5531-e209-9be3-94a94c4ad65c@linaro.org>
Date:   Thu, 16 Feb 2023 10:34:11 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Huacai Chen <chenhuacai@...nel.org>
Cc:     Binbin Zhou <zhoubb.aaron@...il.com>,
        Binbin Zhou <zhoubinbin@...ngson.cn>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jianmin Lv <lvjianmin@...ngson.cn>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        loongarch@...ts.linux.dev, devicetree@...r.kernel.org,
        loongson-kernel@...ts.loongnix.cn
Subject: Re: [PATCH V2 1/2] dt-bindings: interrupt-controller: Add Loongson
 EIOINTC

On 16/02/2023 10:30, Huacai Chen wrote:
> Hi, Krzysztof,
> 
> On Thu, Feb 16, 2023 at 4:10 PM Krzysztof Kozlowski
> <krzysztof.kozlowski@...aro.org> wrote:
>>
>> On 16/02/2023 02:46, Binbin Zhou wrote:
>>> On Tue, Feb 14, 2023 at 8:43 PM Krzysztof Kozlowski
>>> <krzysztof.kozlowski@...aro.org> wrote:
>>>>
>>>> On 14/02/2023 13:40, Binbin Zhou wrote:
>>>>> On Tue, Feb 14, 2023 at 5:53 PM Krzysztof Kozlowski
>>>>> <krzysztof.kozlowski@...aro.org> wrote:
>>>>>>
>>>>>> On 13/02/2023 13:15, Binbin Zhou wrote:
>>>>>>> Add Loongson Extended I/O Interrupt controller binding with DT schema
>>>>>>> format using json-schema.
>>>>>>>
>>>>>>> Signed-off-by: Binbin Zhou <zhoubinbin@...ngson.cn>
>>>>>>> ---
>>>>>>>  .../loongson,eiointc.yaml                     | 80 +++++++++++++++++++
>>>>>>>  1 file changed, 80 insertions(+)
>>>>>>>  create mode 100644 Documentation/devicetree/bindings/interrupt-controller/loongson,eiointc.yaml
>>>>>>>
>>>>>>> diff --git a/Documentation/devicetree/bindings/interrupt-controller/loongson,eiointc.yaml b/Documentation/devicetree/bindings/interrupt-controller/loongson,eiointc.yaml
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..88580297f955
>>>>>>> --- /dev/null
>>>>>>> +++ b/Documentation/devicetree/bindings/interrupt-controller/loongson,eiointc.yaml
>>>>>>> @@ -0,0 +1,80 @@
>>>>>>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>>>>>>> +%YAML 1.2
>>>>>>> +---
>>>>>>> +$id: "http://devicetree.org/schemas/interrupt-controller/loongson,eiointc.yaml#"
>>>>>>> +$schema: "http://devicetree.org/meta-schemas/core.yaml#"
>>>>>>
>>>>>> Drop quotes from bopth.
>>>>>>
>>>>>>> +
>>>>>>> +title: Loongson Extended I/O Interrupt Controller
>>>>>>> +
>>>>>>> +maintainers:
>>>>>>> +  - Binbin Zhou <zhoubinbin@...ngson.cn>
>>>>>>> +
>>>>>>> +description: |
>>>>>>> +  This interrupt controller is found on the Loongson-3 family chips and
>>>>>>> +  Loongson-2K0500 chip and is used to distribute interrupts directly to
>>>>>>> +  individual cores without forwarding them through the HT's interrupt line.
>>>>>>> +
>>>>>>> +allOf:
>>>>>>> +  - $ref: /schemas/interrupt-controller.yaml#
>>>>>>> +
>>>>>>> +properties:
>>>>>>> +  compatible:
>>>>>>> +    enum:
>>>>>>> +      - loongson,eiointc-1.0
>>>>>>
>>>>>> Why not using SoC based compatible? It is preferred.
>>>>>
>>>>> Hi Krzysztof:
>>>>>
>>>>> So far, from the datasheet, I know that only the EXIOINTC of the
>>>>> Loongson-2K0500 is different from the other chips, and that is the
>>>>> "loongson,eio-num-vecs" below, which is 128, while all the others are
>>>>> 256.
>>>>> My original idea was to add this property to make compatible
>>>>> consistent, and also to make it easier to add new chips if they have
>>>>> different eio-num-vecs.
>>>>
>>>> We talk about different things. SoC based compatibles are preferred over
>>>> version ones. This was on the lists expressed many times. Please provide
>>>> a reason why you deviate from general recommendation. Flexibility and
>>>> genericness of bindings is not a reason - it's the opposite of the
>>>> argument, thus this will be a: NAK. :(
>>>>
>>>>
>>> Hi Krzysztof:
>>>
>>> Allow me to give a brief overview of the current status of eiointc (DT-based):
>>>      Loongson-3A series supports eiointc;
>>>      Loongson-2K1000 does not support eiointc now;
>>>      Loongson-2K0500 supports eiointc, with differences from
>>> Loongson-3, e.g. only up to 128 devices are supported;
>>>      Loongson-2K2000 supports eiointc, similar to Loongson-3.
>>>      ....
>>>
>>> As can be seen, there is now a bit of confusion in the chip's design of eiointc.
>>>
>>> The design of eiointc is probably refined step by step with the chip.
>>> The same version of eiointc can be used for multiple chips, and the
>>> same chip series may also use different versions of eiointc. Low-end
>>> chips may use eiointc-2.0, and high-end chips may use eiointc-1.0,
>>> depending on the time it's produced.
>>>
>>> So in the Loongson-2K series I have defined the current state as
>>> eiointc-1.0, using the dts property to indicate the maximum number of
>>> devices supported by eiointc that can be used directly in the driver.
>>>
>>> If there are new changes to the design later on, such as the
>>> definition of registers, we can call it eiointc-2.0, which can also
>>> cover more than one chip.
>>
>> Just go with SoC-based compatibles. If your version is not specific
>> enough, then it is not a good way to represent the hardware.
> EIOINTC is a bit like the existing LIOINTC which is already use
> version to represent hardware.

Heh, so why did you go with version in compatible for liointc if it also
does not match it correctly?

Best regards,
Krzysztof

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