linux-kernel - Re: [PATCH v4 3/3] arm64: dts: imx93: Add phyBOARD-Segin-i.MX93 support

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Date: Tue, 23 Jan 2024 09:25:05 +0100
From: Wadim Egorov <w.egorov@...tec.de>
To: Stefan Wahren <wahrenst@....net>, Mathieu Othacehe <othacehe@....org>, Rob
 Herring <robh+dt@...nel.org>, Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
	Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam
	<festevam@...il.com>, NXP Linux Team <linux-imx@....com>, Li Yang
	<leoyang.li@....com>, Primoz Fiser <primoz.fiser@...ik.com>, Christoph
 Stoidner <c.stoidner@...tec.de>
CC: <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <upstream@...ts.phytec.de>
Subject: Re: [PATCH v4 3/3] arm64: dts: imx93: Add phyBOARD-Segin-i.MX93
 support


Am 23.01.24 um 08:42 schrieb Stefan Wahren:
> Hi Wadim,
>
> Am 23.01.24 um 07:11 schrieb Wadim Egorov:
>> Hey Mathieu,
>>
>> Am 22.01.24 um 10:53 schrieb Mathieu Othacehe:
>>> Add basic support for phyBOARD-Segin-i.MX93.
>>> Main features are:
>>> * eMMC
>>> * Ethernet
>>> * SD-Card
>>> * UART
>>>
>>> Signed-off-by: Mathieu Othacehe <othacehe@....org>
>>> ---
>>>   arch/arm64/boot/dts/freescale/Makefile        |   1 +
>>>   .../dts/freescale/imx93-phyboard-segin.dts    | 141 
>>> ++++++++++++++++++
>>>   .../boot/dts/freescale/imx93-phycore-som.dtsi | 127 ++++++++++++++++
>>>   3 files changed, 269 insertions(+)
>>>   create mode 100644
>>> arch/arm64/boot/dts/freescale/imx93-phyboard-segin.dts
>>>   create mode 100644
>>> arch/arm64/boot/dts/freescale/imx93-phycore-som.dtsi
>>>
>>> diff --git a/arch/arm64/boot/dts/freescale/Makefile
>>> b/arch/arm64/boot/dts/freescale/Makefile
>>> index 2e027675d7bb..65db918c821c 100644
>>> --- a/arch/arm64/boot/dts/freescale/Makefile
>>> +++ b/arch/arm64/boot/dts/freescale/Makefile
>>> @@ -201,6 +201,7 @@ dtb-$(CONFIG_ARCH_MXC) +=
>>> imx8qxp-colibri-iris-v2.dtb
>>>   dtb-$(CONFIG_ARCH_MXC) += imx8qxp-mek.dtb
>>>   dtb-$(CONFIG_ARCH_MXC) += imx8ulp-evk.dtb
>>>   dtb-$(CONFIG_ARCH_MXC) += imx93-11x11-evk.dtb
>>> +dtb-$(CONFIG_ARCH_MXC) += imx93-phyboard-segin.dtb
>>>   dtb-$(CONFIG_ARCH_MXC) += imx93-tqma9352-mba93xxca.dtb
>>>   dtb-$(CONFIG_ARCH_MXC) += imx93-tqma9352-mba93xxla.dtb
>>>   diff --git a/arch/arm64/boot/dts/freescale/imx93-phyboard-segin.dts
>>> b/arch/arm64/boot/dts/freescale/imx93-phyboard-segin.dts
>>> new file mode 100644
>>> index 000000000000..5433c33d1322
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/freescale/imx93-phyboard-segin.dts
>>> @@ -0,0 +1,141 @@
>>> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT)
>>> +/*
>>> + * Copyright (C) 2023 PHYTEC Messtechnik GmbH
>>> + * Author: Wadim Egorov <w.egorov@...tec.de>, Christoph Stoidner
>>> <c.stoidner@...tec.de>
>>> + * Copyright (C) 2024 Mathieu Othacehe <m.othacehe@...il.com>
>>> + *
>>> + * Product homepage:
>>> + * phyBOARD-Segin carrier board is reused for the i.MX93 design.
>>> + *
>>> https://www.phytec.de/produkte/single-board-computer/phyboard-segin-imx6ul/ 
>>>
>>> + */
>>> +
>>> +#include "imx93-phycore-som.dtsi"
>>> +
>>> +/{
>>> +    model = "PHYTEC phyBOARD-Segin-i.MX93";
>>> +    compatible = "phytec,imx93-phyboard-segin",
>>> "phytec,imx93-phycore-som",
>>> +             "fsl,imx93";
>>> +
>>> +    chosen {
>>> +        stdout-path = &lpuart1;
>>> +    };
>>> +
>>> +    reg_usdhc2_vmmc: regulator-usdhc2 {
>>> +        compatible = "regulator-fixed";
>>> +        enable-active-high;
>>> +        gpio = <&gpio3 7 GPIO_ACTIVE_HIGH>;
>>> +        pinctrl-names = "default";
>>> +        pinctrl-0 = <&pinctrl_reg_usdhc2_vmmc>;
>>> +        regulator-min-microvolt = <3300000>;
>>> +        regulator-max-microvolt = <3300000>;
>>> +        regulator-name = "VCC_SD";
>>> +    };
>>> +};
>>> +
>>> +/* GPIOs */
>>> +&gpio1 {
>>> +    pinctrl-names = "default";
>>> +    pinctrl-0 = <&pinctrl_gpio1>;
>>
>> You are doing more than you describing in your changes log.
>> Here you are forcing a gpio-only functionality for the X16 header. But
>> the pins we route down to the X16 expansion connector can be also used
>> differently.
>
> i think the word "forcing" is little bit hard in this case. It doesn't
> define a gpio-hog.

You are defaulting it to be a GPIO.

>
>> Typically we provide device tree overlays for different use cases on
>> this expansion connectors.
>
> Can you please explain why the device tree overlays cannot overwrite the
> pinmuxing?

It can, and it should. Thats why I mentioned to use different overlays 
for different use cases.
I think it is nicer to have a board only defining it's static components.
At this point we do not know what users will use the expansion connector 
for.
Adding this kind of functionality with overlays follows the idea of 
defining components where they are actually used/implemented: soc, 
som/board level.
You can find a few of the adapters we provide as dtsi files in
   arch/arm/boot/dts/nxp/imx/*peb*
Nowadays we have overlays and can use them instead.


>
>>
>> Please drop the muxing.
>>
>> Same applies for the gpio names.
> What's the problem with defining gpio line names for user friendliness?
> The Raspberry Pi has also an expansion header, all the pins can be muxed
> to different functions but still have gpio line names.

This may cause confusion if you use overlays defining other 
functionalities as the names you define.

Regards,
Wadim


>
> Best regards