linux-kernel - Re: [PATCH net-next 4/5] arm64: dts: ti: k3-am62-main: Add timesync router node

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Message-ID: <20230516133101.ezt5jacp6i47nspa@oblivion>
Date:   Tue, 16 May 2023 08:31:01 -0500
From:   Nishanth Menon <nm@...com>
To:     Siddharth Vadapalli <s-vadapalli@...com>,
        Peter Rosin <peda@...ntia.se>, <tony@...mide.com>
CC:     <davem@...emloft.net>, <edumazet@...gle.com>, <kuba@...nel.org>,
        <pabeni@...hat.com>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski@...aro.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <kristo@...nel.org>,
        <vigneshr@...com>, <rogerq@...nel.org>, <nsekhar@...com>,
        <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <srk@...com>
Subject: Re: [PATCH net-next 4/5] arm64: dts: ti: k3-am62-main: Add timesync
 router node

On 17:14-20230111, Siddharth Vadapalli wrote:
> TI's AM62x SoC has a Time Sync Event Router, which enables routing a single
> input signal to multiple recipients. This facilitates syncing all the
> peripherals or processor cores to the input signal which acts as a master
> clock.
> 
> Signed-off-by: Siddharth Vadapalli <s-vadapalli@...com>
> ---
>  arch/arm64/boot/dts/ti/k3-am62-main.dtsi | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-am62-main.dtsi b/arch/arm64/boot/dts/ti/k3-am62-main.dtsi
> index 072903649d6e..4ce59170b6a7 100644
> --- a/arch/arm64/boot/dts/ti/k3-am62-main.dtsi
> +++ b/arch/arm64/boot/dts/ti/k3-am62-main.dtsi
> @@ -649,6 +649,15 @@ cpts@...00 {
>  		};
>  	};
>  
> +	timesync_router: pinctrl@...000 {
> +		compatible = "pinctrl-single";

While I understand that the timesync router is essentially a mux,
pinctrl-single is a specific mux model that is used to model external
facing pins to internal signals - pin mux sections of control module
which is already in place is an example of the same.

Using the pinctrl-single scheme for timesync router is, IMHO, wrong
and limiting to potential functions that timesync router could need
enabling.

Is there a reason for using pinctrl-single rather than writing a
mux-controller / consumer model driver instead or rather simpler a
reg-mux node?

> +		reg = <0x0 0xa40000 0x0 0x800>;
> +		#pinctrl-cells = <1>;
> +		pinctrl-single,register-width = <32>;
> +		pinctrl-single,function-mask = <0x000107ff>;
> +		status = "disabled";
> +	};
> +
-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D