linux-kernel - Re: [PATCH V3 11/17] dt-bindings: arm: mediatek: Add #reset-cells property for MT8192-sys-clock

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Message-ID: <edaf444b9c45e5f36757116fe098749348cb54b7.camel@mediatek.com>
Date:   Tue, 26 Apr 2022 16:24:54 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "mturquette@...libre.com" <mturquette@...libre.com>,
        "sboyd@...nel.org" <sboyd@...nel.org>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>
CC:     "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        Chun-Jie Chen (陳浚桀) 
        <Chun-Jie.Chen@...iatek.com>,
        "wenst@...omium.org" <wenst@...omium.org>,
        Runyang Chen (陈润洋) 
        <Runyang.Chen@...iatek.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH V3 11/17] dt-bindings: arm: mediatek: Add #reset-cells
 property for MT8192-sys-clock

On Mon, 2022-04-25 at 15:44 +0800, Krzysztof Kozlowski wrote:
> On 25/04/2022 04:37, Rex-BC Chen wrote:
> > > > +  '#reset-cells':
> > > > +    maximum: 2
> > > 
> > > Why this is a maximum? Usually this is const, so how do you use
> > > it
> > > (with
> > > what values)?
> > > 
> > 
> > We need to let the driver compatible with previous setting in
> > drivers/clk/mediatek/reset.c
> 
> Then it should be enum [1, 2], because '0' is not valid.
> 
> > There are two use cases in our reset driver:
> > (Refer to [1])
> > 
> > 1. #reset-cells = <1>
> >    When we input the argument, the older driver
> > use is to calculate  
> >    bank and bit by different method. From the implementation of
> >    reset_xlate(), we can see if the argument number is 1, it will
> >    return directly.
> 
> I understand this is an old binding with older compatibles, so this
> should be restricted per each variant (allOf:if:then)... but wait,
> old
> binding did not allow any reset-cells! You add an entirely new
> binding
> property and already want to support some older (deprecated?) way.
> 
> > 
> > 2. #reset-cells = <2>
> >    The input arguments is offset and bit. When we input two
> > arguments,
> >    we can use reset_xlate() to calculate the corresponding id to
> > assert
> >    and deassert.
> > 
> > [1]:
> > 
https://urldefense.com/v3/__https://lore.kernel.org/all/20220422060152.13534-10-rex-bc.chen@mediatek.com/__;!!CTRNKA9wMg0ARbw!0U0Yrp6WQxZ0YNMjaLJbAdq6Zyc524B4CY57-TP7QJ5FoSkCM72VI7mHJyWa1SZCnYTK$
> >  
> > 
> > If it's acceptable, I will add this in commit message.
> 
> 
> Best regards,
> Krzysztof

Hello Krzysztof,

I will let #reset-cells = <1> in next version and abandon the
modification of reset_xlate().

Thanks!

BRs,
Rex