Re: [PATCH V3 1/2] dt-bindings: update riscv plic compatible string

[Anup Patel]

On Wed, Oct 13, 2021 at 6:52 AM <guoren@xxxxxxxxxx> wrote:
>
> From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
>
> Add the compatible string "thead,c900-plic" to the riscv plic
> bindings to support SOCs with thead,c9xx processor cores.
>
> Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
> Cc: Rob Herring <robh@xxxxxxxxxx>
> Cc: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
> Cc: Anup Patel <anup@xxxxxxxxxxxxxx>
> Cc: Atish Patra <atish.patra@xxxxxxx>
>
> ---
>
> Changes since V3:
>  - Rename "c9xx" to "c900"
>  - Add thead,c900-plic in the description section
> ---
>  .../bindings/interrupt-controller/sifive,plic-1.0.0.yaml    | 6 ++++++
>  1 file changed, 6 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 08d5a57ce00f..82629832e5a5 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 +35,11 @@ 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>.
>
> +  While the "thead,c900-plic" would mask IRQ with readl(claim), so it needn't
> +  mask/unmask which needed in RISC-V PLIC. When in IRQS_ONESHOT & IRQCHIP_EOI_THREADED
> +  path, unnecessary mask operation would cause a blocking irq bug in thead,c900-plic.
> +  Because when IRQ is disabled in c900, writel(hwirq, claim) would be invalid.

This is a totally incorrect description of the errata required for C9xx PLIC.

Please don't project non-compliance as a feature of C9xx PLIC.

> +
>  maintainers:
>    - Sagar Kadam <sagar.kadam@xxxxxxxxxx>
>    - Paul Walmsley  <paul.walmsley@xxxxxxxxxx>
> @@ -46,6 +51,7 @@ properties:
>        - enum:
>            - sifive,fu540-c000-plic
>            - canaan,k210-plic
> +          - thead,c900-plic
>        - const: sifive,plic-1.0.0

The PLIC DT node requires two compatible string:
<implementation_compat>, <spec_compat>

The C9xx PLIC is not RISC-V PLIC so, the DT node should
be: "thead,c900-plic", "thead,c9xx-plic"

You need to change "- const: sifive,plic-1.0.0" to
- enum:
    - sifive,plic-1.0.0
    - thead,c9xx-plic

>
>    reg:
> --
> 2.25.1
>

Regards,
Anup