linux-kernel - Re: [PATCH V5 2/3] dt-bindings: update riscv plic compatible string

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Date:   Sun, 24 Oct 2021 13:05:08 +0530
From:   Anup Patel <anup@...infault.org>
To:     Guo Ren <guoren@...nel.org>
Cc:     Atish Patra <atish.patra@....com>, Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Palmer Dabbelt <palmer@...belt.com>,
        Heiko Stübner <heiko@...ech.de>,
        Rob Herring <robh@...nel.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Guo Ren <guoren@...ux.alibaba.com>,
        Rob Herring <robh+dt@...nel.org>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: Re: [PATCH V5 2/3] dt-bindings: update riscv plic compatible string

On Sun, Oct 24, 2021 at 7:03 AM <guoren@...nel.org> wrote:
>
> From: Guo Ren <guoren@...ux.alibaba.com>
>
> Add the compatible string "thead,c900-plic" to the riscv plic
> bindings to support allwinner d1 SOC which contains c906 core.
>
> Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
> Cc: Anup Patel <anup@...infault.org>
> Cc: Atish Patra <atish.patra@....com>
> Cc: Heiko Stuebner <heiko@...ech.de>
> Cc: Rob Herring <robh@...nel.org>
> Cc: Rob Herring <robh+dt@...nel.org>
> Cc: Palmer Dabbelt <palmerdabbelt@...gle.com>
>
> ---
>
> Changes since V5:
>  - Add DT list
>  - Fixup compatible string
>  - Remove allwinner-d1 compatible
>  - make dt_binding_check
>
> Changes since V4:
>  - Update description in errata style
>  - Update enum suggested by Anup, Heiko, Samuel
>
> Changes since V3:
>  - Rename "c9xx" to "c900"
>  - Add thead,c900-plic in the description section
> ---
>  .../interrupt-controller/sifive,plic-1.0.0.yaml   | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
>
> 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 08d5a57ce00f..18b97bfd7954 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
> @@ -35,6 +35,10 @@ description:
>    contains a specific memory layout, which is documented in chapter 8 of the
>    SiFive U5 Coreplex Series Manual <https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf>.
>
> +  The thead,c900-plic couldn't complete masked irq source which has been disabled in
> +  enable register. Add thead_plic_chip which fix up c906-plic irq source completion
> +  problem by unmask/mask wrapper.
> +

This is an incomplete description about how T-HEAD PLIC is different from
RISC-V PLIC.

I would suggest the following:

The T-HEAD C9xx SoC implements a modified/custom T-HEAD PLIC specification
which will mask current IRQ upon read to CLAIM register and will unmask the IRQ
upon write to CLAIM register. The thead,c900-plic compatible string
represents the
custom T-HEAD PLIC specification.

Regards,
Anup

>  maintainers:
>    - Sagar Kadam <sagar.kadam@...ive.com>
>    - Paul Walmsley  <paul.walmsley@...ive.com>
> @@ -42,11 +46,16 @@ maintainers:
>
>  properties:
>    compatible:
> -    items:
> +   oneOf:
> +    - items:
>        - enum:
> -          - sifive,fu540-c000-plic
> -          - canaan,k210-plic
> +        - sifive,fu540-c000-plic
> +        - canaan,k210-plic
>        - const: sifive,plic-1.0.0
> +    - items:
> +      - enum:
> +        - allwinner,sun20i-d1-plic
> +      - const: thead,c900-plic
>
>    reg:
>      maxItems: 1
> --
> 2.25.1
>