linux-kernel - Re: [PATCH v6 3/3] riscv: dts: sophgo: add rtc dt node for CV1800

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Message-ID: <20240116165356eaa221fe@mail.local>
Date: Tue, 16 Jan 2024 17:53:56 +0100
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: Jingbao Qiu <qiujingbao.dlmu@...il.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
	robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
	conor+dt@...nel.org, chao.wei@...hgo.com, unicorn_wang@...look.com,
	paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
	linux-rtc@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
	dlan@...too.org, inochiama@...look.com
Subject: Re: [PATCH v6 3/3] riscv: dts: sophgo: add rtc dt node for CV1800

On 17/01/2024 00:29:28+0800, Jingbao Qiu wrote:
> On Wed, Jan 17, 2024 at 12:03 AM Krzysztof Kozlowski
> <krzysztof.kozlowski@...aro.org> wrote:
> >
> > On 16/01/2024 16:51, Jingbao Qiu wrote:
> > >>> CV1800 is a RISCV based SOC that includes an RTC module. The RTC
> > >>> module has an OSC oscillator
> > >>
> > >>
> > >> I am not going to read pages of description. Please write concise replies.
> > >
> > > Thanks, What I mean is that this hardware includes two functions, RTC
> > > and POR. How should I describe their relationship?
> >
> > Your POR does not need to take any resources, so no need to describe any
> > relationship.
> >
> > ...
> >
> > >>> Your suggestion is, firstly, the por submodule does not have any
> > >>> resources, so it should be deleted.
> > >>
> > >> So where did you delete it? I still see it in this patch.
> > >
> > > Should I completely delete him? How can a por driver obtain device information?
> >
> > Delete completely.
> >
> > Device information? What is this? We already agreed you don't have any
> > resources for POR.
> >
> > ....
> >
> > >> Device is only one thing, not two.
> > >>
> > >>>                     reg = <0x5025000 0x2000>;
> > >>>                     interrupts = <17 IRQ_TYPE_LEVEL_HIGH>;
> > >>>                     clocks = <&osc>;
> > >>> };
> > >>> However, in reality, the POR submodule does not use IRQ and CLK.
> > >>> Please do not hesitate to teach. Thanks.
> > >>
> > >> I expect one device node. How many drivers you have does not matter: you
> > >> can instantiate 100 Linux devices in 100 Linux device drivers.
> > >
> > > I understand what you mean. A device node corresponds to multiple drivers.
> > > Should I completely delete the POR device tree node and add it when
> > > submitting the POR driver?
> >
> > ? I wrote it in previous messages and twice in this thread. Completely
> > delete. You do not add it back! Because if you ever intended to add it
> > back, it should be added since beginning. I don't understand what
> > submitting later would solve.
> >
> > > If that's the case, how can I explain that the rtc device tree node
> > > uses the syscon tag?
> > > How can I describe a POR device in DTS? POR is a submodule of RTC, and
> > > it also has corresponding drivers.
> >
> > I said, there is no need for POR in DTS, because you have nothing there.
> > Why do you insist on putting it on DTS?
> >
> > > It's just that his resources are only shared with RTC's Reg.
> >
> > What resources? Reg? That's not a separate resource.
> 
> I'm very sorry about this.
> But I found a binding file that only contains Reg and Compatible.
> 
> rtc@...20000 {
> compatible = "cirrus,ep9301-rtc";
> reg = <0x80920000 0x100>;
> };
> 
> Link: Documentation/devicetree/bindings/rtc/cirrus,ep9301-rtc.yaml
> 
> >
> > To summarize: Drop POR from DTS and never bring it back, unless you come
> > with some different arguments, which you did not say already.
> >
> 
> You are right, if there is no por device tree node, how can the por
> driver obtain the Reg?

I guess the question is why don't you register everything from the RTC
driver?


-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com