Re: [PATCH v2 2/4] dt-bindings: firmware: thead,th1520: Add resets for GPU clkgen

[Conor Dooley <conor@kernel.org>]

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On Mon, Apr 14, 2025 at 08:52:56PM +0200, Michal Wilczynski wrote:
> Extend the TH1520 AON firmware bindings to describe the GPU clkgen reset
> line, required for proper GPU clock and reset sequencing.
> 
> The T-HEAD TH1520 GPU requires coordinated management of two clocks
> (core and sys) and two resets (GPU core reset and GPU clkgen
> reset).  Only the clkgen reset is exposed at the AON level, to support
> SoC-specific initialization handled through a generic PM domain. The GPU
> core reset remains described in the GPU device node, as from the GPU
> driver's perspective, there is only a single reset line [1].
> 
> This follows upstream maintainers' recommendations [2] to abstract
> SoC specific details into the PM domain layer rather than exposing them
> to drivers directly.
> 
> [1] - https://lore.kernel.org/all/816db99d-7088-4c1a-af03-b9a825ac09dc@imgtec.com/
> [2] - https://lore.kernel.org/all/38d9650fc11a674c8b689d6bab937acf@kernel.org/
> 
> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
> ---
>  .../devicetree/bindings/firmware/thead,th1520-aon.yaml        | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/firmware/thead,th1520-aon.yaml b/Documentation/devicetree/bindings/firmware/thead,th1520-aon.yaml
> index bbc183200400de7aadbb21fea21911f6f4227b09..6ea3029c222df9ba6ea7d423b92ba248cfb02cc0 100644
> --- a/Documentation/devicetree/bindings/firmware/thead,th1520-aon.yaml
> +++ b/Documentation/devicetree/bindings/firmware/thead,th1520-aon.yaml
> @@ -32,6 +32,13 @@ properties:
>      items:
>        - const: aon
>  
> +  resets:
> +    maxItems: 1
> +
> +  reset-names:
> +    items:
> +      - const: gpu-clkgen
> +
>    "#power-domain-cells":
>      const: 1
>  
> @@ -39,6 +46,8 @@ required:
>    - compatible
>    - mboxes
>    - mbox-names
> +  - resets
> +  - reset-names

Given these are new required properties, have you made sure in the
driver that their absence will not cause problems with older
devicetrees? I took a brief look at the driver, and it _looked_ like you
were failing if they were not there? It was a brief look though, tbf.

>    - "#power-domain-cells"
>  
>  additionalProperties: false
> @@ -49,5 +58,7 @@ examples:
>          compatible = "thead,th1520-aon";
>          mboxes = <&mbox_910t 1>;
>          mbox-names = "aon";
> +        resets = <&rst 0>;
> +        reset-names = "gpu-clkgen";
>          #power-domain-cells = <1>;
>      };
> 
> -- 
> 2.34.1
> 

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