linux-kernel - Re: [PATCH V2 1/2] dt-bindings: interrupt-controller: Add Loongson EIOINTC

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Date:   Thu, 16 Feb 2023 17:30:45 +0800
From:   Huacai Chen <chenhuacai@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.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

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.

Huacai
>
> Best regards,
> Krzysztof
>