netdev - Re: [PATCH v4 3/4] DO_NOT_MERGE arm64: dts: ti: Add AM62x MCAN MAIN domain transceiver overlay

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Date:   Mon, 1 May 2023 19:18:19 -0500
From:   Nishanth Menon <nm@...com>
To:     Judith Mendez <jm@...com>
CC:     Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, <linux-can@...r.kernel.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Schuyler Patton <spatton@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        Simon Horman <simon.horman@...igine.com>
Subject: Re: [PATCH v4 3/4] DO_NOT_MERGE arm64: dts: ti: Add AM62x MCAN MAIN
 domain transceiver overlay

On 17:46-20230501, Judith Mendez wrote:
> Add an overlay for main domain MCAN on AM62x SK. The AM62x
> SK board does not have on-board CAN transceiver so instead
> of changing the DTB permanently, add an overlay to enable
> MAIN domain MCAN and support for 1 CAN transceiver.
> 
> This DT overlay can be used with the following EVM:
> Link: https://www.ti.com/tool/TCAN1042DEVM
> 
> Signed-off-by: Judith Mendez <jm@...com>
> ---
> Changelog:
> v3:
>  1. Add link for specific board
>  
>  arch/arm64/boot/dts/ti/Makefile               |  2 ++
>  .../boot/dts/ti/k3-am625-sk-mcan-main.dtso    | 35 +++++++++++++++++++
>  2 files changed, 37 insertions(+)
>  create mode 100644 arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso
> 
> diff --git a/arch/arm64/boot/dts/ti/Makefile b/arch/arm64/boot/dts/ti/Makefile
> index c83c9d772b81..abe15e76b614 100644
> --- a/arch/arm64/boot/dts/ti/Makefile
> +++ b/arch/arm64/boot/dts/ti/Makefile
> @@ -9,8 +9,10 @@
>  # alphabetically.
>  
>  # Boards with AM62x SoC
> +k3-am625-sk-mcan-dtbs := k3-am625-sk.dtb k3-am625-sk-mcan-main.dtbo

NAK.
https://lore.kernel.org/all/4e406c96-3f47-1695-324f-a9e45be8c142@ti.com/

Same reasons - we don't want specific instance based overlays please -
that would'nt make sense - maxbitrate will depend on transceiver so it
has nothing to do with mcan-main or mcan-mcu and has everything to do
with the board that is plugged in.

>  dtb-$(CONFIG_ARCH_K3) += k3-am625-beagleplay.dtb
>  dtb-$(CONFIG_ARCH_K3) += k3-am625-sk.dtb
> +dtb-$(CONFIG_ARCH_K3) += k3-am625-sk-mcan.dtb
>  dtb-$(CONFIG_ARCH_K3) += k3-am62-lp-sk.dtb
>  
>  # Boards with AM62Ax SoC
> diff --git a/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso
> new file mode 100644
> index 000000000000..0a7b2f394f87
> --- /dev/null
> +++ b/arch/arm64/boot/dts/ti/k3-am625-sk-mcan-main.dtso

If you are going down this road: am625-sk-tcan10242d.dsto (enable main
and mcu?) or something reasonable. Though looking at the pins, I fail
to see how this physically plugs into AM625-SK (I am hoping the answer
isn't breadboard or jumper wires..).



> @@ -0,0 +1,35 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/**
> + * DT overlay for MCAN transceiver in main domain on AM625 SK
> + *
> + * Copyright (C) 2022 Texas Instruments Incorporated - https://www.ti.com/
> + */
> +
> +/dts-v1/;
> +/plugin/;
> +
> +#include "k3-pinctrl.h"
> +
> +&{/} {
> +	transceiver1: can-phy0 {
> +		compatible = "ti,tcan1042";
> +		#phy-cells = <0>;
> +		max-bitrate = <5000000>;
> +	};
> +};
> +
> +&main_pmx0 {
> +	main_mcan0_pins_default: main-mcan0-pins-default {
> +		pinctrl-single,pins = <
> +			AM62X_IOPAD(0x1dc, PIN_INPUT, 0) /* (E15) MCAN0_RX */
> +			AM62X_IOPAD(0x1d8, PIN_OUTPUT, 0) /* (C15) MCAN0_TX */
> +		>;
> +	};
> +};
> +
> +&main_mcan0 {
> +	status = "okay";
> +	pinctrl-names = "default";
> +	pinctrl-0 = <&main_mcan0_pins_default>;
> +	phys = <&transceiver1>;
> +};
> -- 
> 2.17.1
> 

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D