Re: [PATCH 1/2] arm64: dts: rockchip: correct uart mux for Radxa ZERO3

From: Ed W <lists@wildgooses.com>
To: "FUKAUMI Naoki" <naoki@radxa.com>,
	"Heiko Stübner" <heiko@sntech.de>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] arm64: dts: rockchip: correct uart mux for Radxa ZERO3
Date: Fri, 19 Sep 2025 10:28:54 +0100	[thread overview]
Message-ID: <da24e503-cb43-45e7-99ff-38eab11a203b@wildgooses.com> (raw)
In-Reply-To: <0DB47BC84E90B0E6+694b1274-4826-4ec1-9aa2-ca8aa790f61a@radxa.com>

On 19/09/2025 00:57, FUKAUMI Naoki wrote:
> Hi Heiko, Ed,
>
> On 9/19/25 01:18, Heiko Stübner wrote:
>> Am Donnerstag, 18. September 2025, 17:23:04 Mitteleuropäische Sommerzeit schrieb Ed W:
>>> Personally, and I'm saying this as a user who is technical enough to fix the definitions, it
>>> took me
>>> quite a few days to figure out what was wrong with the definitions and understand the intricate
>>> tree
>>> of dtsi includes, to finally figure out why I couldn't just do a "status = "okay";" to enable the
>>> UARTs... (which is roughly what is shown in several radxa supplied overlays to enable uarts on
>>> various boards)
>>>
>>> So my vote would be to correctly define all the hardware for a given board. Then users can
>>> simply do
>>> a status="okay" to enable and off they go.
>>
>> And I'd agree with that argument. Setting up the needed pinctrl settings
>> for the peripherals described in the device documentation
>> ( https://docs.radxa.com/en/zero/zero3/hardware-design/hardware-interface#gpio-interface )
>>
>> is the sensible thing to do. While keeping the peripherals itself disabled
>> and for the user to decide which peripheral to enable.
>
> I'm not strongly opposed to this policy, but I thought if you're going to do this, you should do
> it for everything, not just UARTs.
>
> Best regards,
>
> -- 
> FUKAUMI Naoki
> Radxa Computer (Shenzhen) Co., Ltd.

I would most definitely be in favour of doing this for all peripherals! Yes please!

I have a selection of Zero 3W and E devices here. We are going to potentially use them in an OEM
capacity, and I might have some I2C devices to plug into them in the future, and for example would
like to get the I2C working on the pins (is it 2 and 4?). It will be at least some weeks before I
can work on that, but if you want to offer some support to fixup at least that device I won't decline!

Thanks for making these boards

Ed W

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