linux-kernel - Re: [PATCH 3/3] dt-bindings: riscv: sifive: Add SiFive Private L2 cache controller

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Date:   Mon, 26 Jun 2023 11:26:00 +0800
From:   Eric Lin <eric.lin@...ive.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     conor@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, palmer@...belt.com,
        paul.walmsley@...ive.com, aou@...s.berkeley.edu, maz@...nel.org,
        chenhuacai@...nel.org, baolu.lu@...ux.intel.com, will@...nel.org,
        kan.liang@...ux.intel.com, nnac123@...ux.ibm.com,
        pierre.gondois@....com, jgross@...e.com, chao.gao@...el.com,
        maobibo@...ngson.cn, linux-riscv@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dslin1010@...il.com, Zong Li <zong.li@...ive.com>,
        Nick Hu <nick.hu@...ive.com>,
        Greentime Hu <greentime.hu@...ive.com>
Subject: Re: [PATCH 3/3] dt-bindings: riscv: sifive: Add SiFive Private L2
 cache controller

Hi Krzysztof,

On Fri, Jun 16, 2023 at 6:45 PM Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:
>
> On 16/06/2023 08:32, Eric Lin wrote:
> > This add YAML DT binding documentation for SiFive Private L2
> > cache controller
> >
> > Signed-off-by: Eric Lin <eric.lin@...ive.com>
> > Reviewed-by: Zong Li <zong.li@...ive.com>
> > Reviewed-by: Nick Hu <nick.hu@...ive.com>
> > ---
> >  .../bindings/riscv/sifive,pL2Cache0.yaml      | 81 +++++++++++++++++++
> >  1 file changed, 81 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/riscv/sifive,pL2Cache0.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/riscv/sifive,pL2Cache0.yaml b/Documentation/devicetree/bindings/riscv/sifive,pL2Cache0.yaml
> > new file mode 100644
> > index 000000000000..b5d8d4a39dde
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/riscv/sifive,pL2Cache0.yaml
> > @@ -0,0 +1,81 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +# Copyright (C) 2023 SiFive, Inc.
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/riscv/sifive,pL2Cache0.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: SiFive Private L2 Cache Controller
> > +
> > +maintainers:
> > +  - Greentime Hu  <greentime.hu@...ive.com>
> > +  - Eric Lin      <eric.lin@...ive.com>
> > +
> > +description:
> > +  The SiFive Private L2 Cache Controller is per hart and communicates with both the upstream
> > +  L1 caches and downstream L3 cache or memory, enabling a high-performance cache subsystem.
> > +  All the properties in ePAPR/DeviceTree specification applies for this platform.
>
> Drop the last sentence. Why specification would not apply?
>
OK, I'll drop it in v2.

> > +
> > +allOf:
> > +  - $ref: /schemas/cache-controller.yaml#
> > +
> > +select:
> > +  properties:
> > +    compatible:
> > +      contains:
> > +        enum:
> > +          - sifive,pL2Cache0
> > +          - sifive,pL2Cache
> > +
> > +  required:
> > +    - compatible
> > +
> > +properties:
> > +  compatible:
> > +    items:
>
>
> You have only one item, so no need for items... unless you just missed
> proper fallback.

OK, I'll fix it in v2.

>
> > +      - enum:
> > +          - sifive,pL2Cache0
> > +          - sifive,pL2Cache1
>
> What is "0" and "1" here? What do these compatibles represent? Why they
> do not have any SoC related part?

The pL2Cache1 has minor changes in hardware, but it can use the same
pl2 cache driver.
May I ask, what do you mean about the SoC-related part? Thanks.

>
> > +
> > +  cache-block-size:
> > +    const: 64
> > +
> > +  cache-level:
> > +    const: 2
> > +
> > +  cache-sets:
> > +    const: 512
> > +
> > +  cache-size:
> > +    const: 262144
>
> Are you sure? So all private L2 cache controllers will have fixed size
> of cache?

The private L2 cache controllers will have different sizes.
OK, I'll fix in v2.

>
> > +
> > +  cache-unified: true
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  next-level-cache: true
> > +
> > +additionalProperties: false
> > +
> > +required:
>
> required: goes before additionalProperties:.
>
OK, I'll fix it in v2.
Thanks for the review.

Best Regards,
Eric Lin.
>
> Best regards,
> Krzysztof
>