linux-kernel - Re: [PATCH 3/3] riscv: dts: spacemit: define a SPI controller node

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Message-ID: <0053c0ca-340f-46fd-adb1-6af6928717ee@riscstar.com>
Date: Thu, 18 Sep 2025 09:20:34 -0500
From: Alex Elder <elder@...cstar.com>
To: Yixun Lan <dlan@...too.org>
Cc: broonie@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
 conor+dt@...nel.org, linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
 paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
 alex@...ti.fr, p.zabel@...gutronix.de, spacemit@...ts.linux.dev,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] riscv: dts: spacemit: define a SPI controller node

On 9/18/25 9:06 AM, Yixun Lan wrote:
> Hi Alex,
> 
> On 08:51 Thu 18 Sep     , Alex Elder wrote:
>> On 9/18/25 8:32 AM, Yixun Lan wrote:
>>>> +			spi3: spi@...1c000 {
>>>> +				compatible = "spacemit,k1-spi";
>>>> +				reg = <0x0 0xd401c000 0x0 0x30>;
>>>> +				#address-cells = <1>;
>>>> +				#size-cells = <0>;
>>>> +				clocks = <&syscon_apbc CLK_SSP3>,
>>>> +					 <&syscon_apbc CLK_SSP3_BUS>;
>>> ..
>>>> +				clock-names = "core",
>>>> +					      "bus";
>>> can you simply put them together in one line? it's kind of tedious to split..
>>
>> Sure I can do that.  I've seen it both ways.
>>
> right, it's merely a coding style I want to enforce, to make it slightly consistent
> 
>>>> +				resets = <&syscon_apbc RESET_SSP3>;
>>>> +				interrupts-extended = <&plic 55>;
>>> why use interrupts-extended?
>>
>> Because it specifies both the controller and interrupt number
>> explicitly.  Why *not* use interrupts-extended?
>>
> It's just unnecessary, the SPI node will fall back to find parent node's interrupt
> which already specific as &plic, brings no benefits

The benefit it brings is that I don't have to search backward to
see what the interrupt controller is.  I realize it's redundant
but I do prefer interrupts-extended over just interrupts.

					-Alex

> 
>>>> +				spacemit,k1-ssp-id = <3>;
>>>> +				dmas = <&pdma 20>,
>>>> +				       <&pdma 19>;
>