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

From: Yixun Lan <dlan@gentoo.org>
To: Alex Elder <elder@riscstar.com>
Cc: broonie@kernel.org, robh@kernel.org, krzk+dt@kernel.org,
	conor+dt@kernel.org, linux-spi@vger.kernel.org,
	devicetree@vger.kernel.org, paul.walmsley@sifive.com,
	palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr,
	p.zabel@pengutronix.de, spacemit@lists.linux.dev,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] riscv: dts: spacemit: define a SPI controller node
Date: Thu, 18 Sep 2025 23:04:50 +0800	[thread overview]
Message-ID: <20250918150450-GYD1274501@gentoo.org> (raw)
In-Reply-To: <0053c0ca-340f-46fd-adb1-6af6928717ee@riscstar.com>

Hi Alex,

On 09:20 Thu 18 Sep     , Alex Elder wrote:
> 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@d401c000 {
> >>>> +				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.
> 
although both should work fine, I do prefer simple "interrupts" version
for dts wide consistence, at least for SpacemiT

while reading Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
interrupts-extended is useful when there are multi interrupt parents, or need
to specific different one..

Yes, we have different opinion here, let's wait and see what DT maintainer think

-- 
Yixun Lan (dlan)

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