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

Geert Uytterhoeven
2025-05-23T09:06:08Z

Hi Thierry,

On Thu, 15 May 2025 at 16:18, Thierry Bultel
<thierry.bultel.yh@bp.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@bp.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@80005000 {
> 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@linux-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