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

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Message-ID: <CAJRtX8Tkie+ykLv8L2EgBQcy9tVP5Yz-_J_eHE-9N9hjt+6gkg@mail.gmail.com>
Date: Wed, 17 Jan 2024 00:29:28 +0800
From: Jingbao Qiu <qiujingbao.dlmu@...il.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: alexandre.belloni@...tlin.com, 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 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?
Thank you again.

Best regards,
Jingbao Qiu