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From:   Chen-Yu Tsai <wenst@chromium.org>
Date:   Mon, 16 Aug 2021 14:10:21 +0800
Message-ID: <CAGXv+5HohMwU8jow5QXO5MK1tO+u=5YsfhArBWCP4Dgm1Q8igg@mail.gmail.com>
Subject: Re: [PATCH v10 1/2] dt-bindings: pinctrl: mt8195: add rsel define
To:     Linus Walleij <linus.walleij@linaro.org>
Cc:     "zhiyong.tao" <zhiyong.tao@mediatek.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Sean Wang <sean.wang@kernel.org>,
        srv_heupstream <srv_heupstream@mediatek.com>,
        hui.liu@mediatek.com, Eddie Huang <eddie.huang@mediatek.com>,
        Light Hsieh <light.hsieh@mediatek.com>,
        Biao Huang <biao.huang@mediatek.com>,
        Hongzhou Yang <hongzhou.yang@mediatek.com>,
        Sean Wang <sean.wang@mediatek.com>,
        Seiya Wang <seiya.wang@mediatek.com>,
        Devicetree List <devicetree@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
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On Thu, Aug 5, 2021 at 7:02 AM Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Thu, Jul 29, 2021 at 11:43 AM Chen-Yu Tsai <wenst@chromium.org> wrote:
> > On Thu, Jul 29, 2021 at 4:23 PM zhiyong.tao <zhiyong.tao@mediatek.com> wrote:
>
> > > The rsel actual bias resistance of each setting is different in
> > > different IC. we think that the define "MTK_PULL_SET_RSEL_000" is more
> > > common for all different IC.
> >
> > I see. I personally prefer having things clearly described. I can
> > understand this might be an extra burden to support different chips
> > with different parameters, though this should be fairly straightforward
> > with lookup tables tied to the compatible strings.
> >
> > Let's see if Rob and Linus have anything to add.
>
> Not much. We have "soft pushed" for this to be described as generic
> as possible, using SI units (ohms). But we also allow vendor-specific
> numbers in this attribute. Especially when reverse engineering SoCs
> that the contributor don't really have specs on (example M1 Mac).
>
> The intent with the SI units is especially for people like you folks working
> with Chromium to be able to use different SoCs and not feel lost
> to a forest of different ways of doing things and associated
> mistakes because vendors have hopelessly idiomatic pin configs.

I'll take that as "use SI units whenever possible and reasonable".

Thanks.

ChenYu