linux-kernel - Re: [PATCH v9 01/10] dt-bindings: serial: Added secondary clock for RZ/T2H RSCI

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Message-ID: <CAMuHMdW9A1hoeF4nZ-n1z-SkHhW0Hgrzcqtm9ekF+q0AAuFX+A@mail.gmail.com>
Date: Fri, 23 May 2025 11:05:54 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Thierry Bultel <thierry.bultel.yh@...renesas.com>
Cc: thierry.bultel@...atsea.fr, linux-renesas-soc@...r.kernel.org, 
	paul.barker.ct@...renesas.com, linux-kernel@...r.kernel.org, 
	linux-serial@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v9 01/10] dt-bindings: serial: Added secondary clock for
 RZ/T2H RSCI

Hi Thierry,

On Thu, 15 May 2025 at 16:18, Thierry Bultel
<thierry.bultel.yh@...renesas.com> wrote:
> At boot, the default clock is the PCLKM core clock (synchronous
> clock, which is enabled by the bootloader).
> For different baudrates, the asynchronous clock input must be used.
> Clock selection is made by an internal register of RCSI.
>
> Also remove the unneeded serial0 alias from the dts example.
>
> Signed-off-by: Thierry Bultel <thierry.bultel.yh@...renesas.com>
> ---
> Changes v8->v9:
>  - typo in description
>  - named clocks 'operational' and 'bus', and added optional 'sck' clock
>  - uses value of 2nd core clock in example to break the dependency on cpg patch

Thanks for the update!

> --- a/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> +++ b/Documentation/devicetree/bindings/serial/renesas,rsci.yaml
> @@ -35,10 +35,17 @@ properties:
>        - const: tei
>
>    clocks:
> -    maxItems: 1
> +    minItems: 2
> +    maxItems: 3
>
>    clock-names:
> -    const: fck # UART functional clock
> +    minItems: 2
> +    maxItems: 3

I think you can drop the maxItems.

> +    items:
> +      enum:
> +        - operation
> +        - bus
> +        - sck # optional external clock input

The addition of this (third) clock is not mentioned in the patch
description.

>
>    power-domains:
>      maxItems: 1
> @@ -58,11 +65,7 @@ unevaluatedProperties: false
>  examples:
>    - |
>      #include <dt-bindings/interrupt-controller/arm-gic.h>
> -    #include <dt-bindings/clock/renesas-cpg-mssr.h>
> -
> -    aliases {
> -        serial0 = &sci0;
> -    };
> +    #include <dt-bindings/clock/renesas,r9a09g077-cpg-mssr.h>

Now you no longer use any definitions from this header file, please
keep on using <dt-bindings/clock/renesas-cpg-mssr.h> instead, to relax
the dependency on [PATCH v9 02/10].

>
>      sci0: serial@...05000 {
>          compatible = "renesas,r9a09g077-rsci";
> @@ -72,7 +75,7 @@ examples:
>                       <GIC_SPI 592 IRQ_TYPE_EDGE_RISING>,
>                       <GIC_SPI 593 IRQ_TYPE_LEVEL_HIGH>;
>          interrupt-names = "eri", "rxi", "txi", "tei";
> -        clocks = <&cpg CPG_MOD 108>;
> -        clock-names = "fck";
> +        clocks = <&cpg CPG_MOD 8>, <&cpg CPG_CORE 13>;
> +        clock-names = "operation", "bus";
>          power-domains = <&cpg>;
>      };

The rest LGTM.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds