linux-kernel - Re: [PATCH v2 1/2] dt-binding: pinctrl: Add NPCM8XX pinctrl and GPIO documentation

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Message-ID: <CAP6Zq1hEM67cZt-pcn95VpcPcOVnySb=3XV69irzdkuAuXgofw@mail.gmail.com>
Date:   Tue, 20 Sep 2022 20:00:14 +0300
From:   Tomer Maimon <tmaimon77@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Rob Herring <robh@...nel.org>,
        Avi Fishman <avifishman70@...il.com>,
        Tali Perry <tali.perry1@...il.com>,
        Joel Stanley <joel@....id.au>,
        Patrick Venture <venture@...gle.com>,
        Nancy Yuen <yuenn@...gle.com>,
        Benjamin Fair <benjaminfair@...gle.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Jonathan Neuschäfer <j.neuschaefer@....net>,
        zhengbin13@...wei.com, OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] dt-binding: pinctrl: Add NPCM8XX pinctrl and GPIO documentation

On Tue, 20 Sept 2022 at 18:16, Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:
>
> On 20/09/2022 11:27, Tomer Maimon wrote:
> > On Tue, 20 Sept 2022 at 11:47, Krzysztof Kozlowski
> > <krzysztof.kozlowski@...aro.org> wrote:
> >>
> >> On 20/09/2022 10:32, Tomer Maimon wrote:
> >>> On Tue, 20 Sept 2022 at 11:21, Krzysztof Kozlowski
> >>> <krzysztof.kozlowski@...aro.org> wrote:
> >>>>
> >>>> On 20/09/2022 09:59, Tomer Maimon wrote:
> >>>>>>>>>>> +      pinctrl: pinctrl@...00000 {
> >>>>>>>>>>> +        compatible = "nuvoton,npcm845-pinctrl";
> >>>>>>>>>>> +        ranges = <0x0 0x0 0xf0010000 0x8000>;
> >>>>>>>>>>> +        #address-cells = <1>;
> >>>>>>>>>>> +        #size-cells = <1>;
> >>>>>>>>>>> +        nuvoton,sysgcr = <&gcr>;
> >>>>>>>>>>> +
> >>>>>>>>>>> +        gpio0: gpio@...10000 {
> >>>>>>>>>>
> >>>>>>>>>> gpio@0
> >>>>>>>>>>
> >>>>>>>>>> Is this really a child block of the pinctrl? Doesn't really look like it
> >>>>>>>>>> based on addressess. Where are the pinctrl registers? In the sysgcr? If
> >>>>>>>>>> so, then pinctrl should be a child of it. But that doesn't really work
> >>>>>>>>>> too well with gpio child nodes...
> >>>>>>>>> the pin controller mux is handled by sysgcr this is why the sysgcr in
> >>>>>>>>> the mother node,
> >>>>>>>>> and the pin configuration are handled by the GPIO registers.  each
> >>>>>>>>> GPIO bank (child) contains 32 GPIO.
> >>>>>>>>> this is why the GPIO is the child node.
> >>>>>>>>
> >>>>>>>> Then maybe pinctrl should be the sysgcr and expose regmap for other devices?
> >>>>>>> The pin controller using the sysgcr to handle the pinmux, this is why
> >>>>>>> the sysgcr is in the mother node, is it problematic?
> >>>>>>
> >>>>>> You said pin-controller mux registers are in sysgcr, so it should not be
> >>>>>> used via syscon.
> >>>>> Sorry but maybe I missed something.
> >>>>> the sysgcr is used for miscellaneous features and not only for the pin
> >>>>> controller mux, this is why it used syscon and defined in the dtsi:
> >>>>>                 gcr: system-controller@...00000 {
> >>>>>                         compatible = "nuvoton,npcm845-gcr", "syscon";
> >>>>>                         reg = <0x0 0xf0800000 0x0 0x1000>;
> >>>>>                 };
> >>>>>>
> >>>>>> Please provide address map description to convince us that this is
> >>>>>> correct HW representation.
> >>>>> GCR (sysgcr) registers 0xf0800000-0xf0801000 - used for miscellaneous
> >>>>> features, not only pin mux.
> >>>>> GPIO0 0xf0010000-0xf0011000
> >>>>> GPIO1 0xf0011000-0xf0012000
> >>>>> ...
> >>>>> GPIO7 0xf0017000-0xf0018000
> >>>>>>
> >>>>
> >>>> Then why your pinctrl is in sysgcr IO range? (pinctrl@...00000)
> >>> you suggest using pinctrl@0 or pinctrl@...10000 and not
> >>> pinctrl@...00000 because 0xf0800000 is the GCR address that serve
> >>> miscellaneous features and not only pinmux controller ?
> >>
> >> If you have a map like you pasted, then DTS like this:
> >>
> >> syscon@...00000 {}
> >> pinctrl@...00000 {
> >>   gpio@...10000 {}
> >> }
> >>
> >> Is quite weird, don't you think? You have two devices on the same unit
> >> address which is not allowed. You have child of pinctrl with entirely
> > O.K.
> >> different unit address, so how is it its child?
> > The pinctrl node name will modify the pinctrl@...10000 the same as the
> > range property and the start of the child registers,is it fine?
>
> We are all busy, so I don't have that much bandwidth to review each of
> your many solutions and instead poking me with every possible solution,
> I would prefer if you think a bit how this all should work and look.
>
> I don't know if it is fine. Why you should have two devices like this:
> pinctrl@...10000 {
> gpio@...10000 {}
> }
>
> ???
> Instead of one device? Answer such questions to yourself before asking
> me. Please come with reasonable DTS describing the hardware.
>
Will do, thanks.
> Best regards,
> Krzysztof

Best regards,

Tomer