linux-kernel - Re: [PATCH v1 01/15] dt-binding: remoteproc: mediatek: Support dual-core SCP

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Message-ID: <dd3ea397-fa21-abe5-85ad-b8a4818dc011@linaro.org>
Date:   Wed, 1 Jun 2022 13:50:11 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Tinghan Shen <tinghan.shen@...iatek.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        Daisuke Nojiri <dnojiri@...omium.org>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        "Dustin L. Howett" <dustin@...ett.net>,
        Tzung-Bi Shih <tzungbi@...nel.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Prashant Malani <pmalani@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        Brian Norris <briannorris@...omium.org>
Cc:     linux-remoteproc@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        chrome-platform@...ts.linux.dev,
        Project_Global_Chrome_Upstream_Group@...iatek.com,
        weishunc@...gle.com
Subject: Re: [PATCH v1 01/15] dt-binding: remoteproc: mediatek: Support
 dual-core SCP

On 01/06/2022 13:21, Tinghan Shen wrote:
> The SCP co-processor is a dual-core RISC-V MCU on MT8195.
> 
> Add a new property to identify each core and helps to find drivers
> through device tree API to cooperate with each other, e.g. boot flow and
> watchdog timeout flow.
> 
> Add a new compatile for the driver of SCP 2nd core.
> 
> Signed-off-by: Tinghan Shen <tinghan.shen@...iatek.com>
> ---
>  .../devicetree/bindings/remoteproc/mtk,scp.yaml      | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml b/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml
> index eec3b9c4c713..b181786d9575 100644
> --- a/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml
> +++ b/Documentation/devicetree/bindings/remoteproc/mtk,scp.yaml
> @@ -20,6 +20,7 @@ properties:
>        - mediatek,mt8186-scp
>        - mediatek,mt8192-scp
>        - mediatek,mt8195-scp
> +      - mediatek,mt8195-scp-dual
>  
>    reg:
>      description:
> @@ -57,6 +58,16 @@ properties:
>    memory-region:
>      maxItems: 1
>  
> +  mediatek,scp-core:
> +    $ref: /schemas/types.yaml#/definitions/uint32-array
> +    description:
> +      The property value is a list with 2 items, a core id and a phandle

uint32, not phandle.

> +      to the sibling SCP node. 

Skip this. First part is obvious from the schema, second part should be
described via items.

The core id represents the id of the dts node contains
> +      this property. The valid values of core id are 0 and 1 for dual-core SCP.
> +      The phandle of sibling SCP node is used to find the register settings,
> +      trigger core dependent callback, and invoke rproc API.

Entire description did not help me to understand what's this. So far it
looks like it is not a hardware property but some programming help, so
it does not look like properly described in bindings.

> +    maxItems: 1

In description you said - two items.

You need allOf:if:then disallowing this property for other variants.

> +
>  required:
>    - compatible
>    - reg
> @@ -115,6 +126,7 @@ examples:
>          reg-names = "sram", "cfg", "l1tcm";
>          clocks = <&infracfg CLK_INFRA_SCPSYS>;
>          clock-names = "main";
> +        mediatek,scp-core = <0 &scp_dual>;

This looks like phandle, so wrong type.
>  
>          cros_ec {
>              mediatek,rpmsg-name = "cros-ec-rpmsg";


Best regards,
Krzysztof