linux-kernel - Re: [PATCH v5 2/6] dt-bindings: PCI: renesas,pci-rcar-gen2: Add device tree support for r9a06g032

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Message-ID: <20220506143518.3ed9765b@bootlin.com>
Date:   Fri, 6 May 2022 14:35:18 +0200
From:   Herve Codina <herve.codina@...tlin.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Rob Herring <robh@...nel.org>,
        Marek Vasut <marek.vasut+renesas@...il.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Magnus Damm <magnus.damm@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        linux-pci <linux-pci@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sergey Shtylyov <s.shtylyov@....ru>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Clement Leger <clement.leger@...tlin.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: Re: [PATCH v5 2/6] dt-bindings: PCI: renesas,pci-rcar-gen2: Add
 device tree support for r9a06g032

Hi All,

On Tue, 3 May 2022 11:37:31 +0200
Geert Uytterhoeven <geert@...ux-m68k.org> wrote:

> Hi Krzysztof,
> 
> On Tue, May 3, 2022 at 11:29 AM Krzysztof Kozlowski
> <krzysztof.kozlowski@...aro.org> wrote:
> > On 03/05/2022 08:51, Geert Uytterhoeven wrote:  
> > >>>> This should not be a reason why a property is or is not required. Either
> > >>>> this is required for device operation or not. If it is required, should
> > >>>> be in the bindings. Otherwise what are you going to do in the future?
> > >>>> Add a required property breaking the ABI?  
> > >>>
> > >>> The problem is that there are no bindings for the reset controller
> > >>> (actually the reset controller feature of the system-controller) yet.
> > >>> Yeah, we can just add #reset-cells = <1> to the system-controller
> > >>> device node, but we cannot add the actual resets properties to the
> > >>> consumers, until the actual cell values are defined.  
> > >>
> > >> Sounds like you should implement providers first. Or just live with the
> > >> warning as a reminder to implement the reset provider?  
> > >
> > > I'd go for the latter. The upstream r9a06g032.dtsi is still under active
> > > development. Until very recently, the only device supported was the
> > > serial console.  
> >
> > For clocks we use in such cases fixed-clock placeholders or empty
> > phandles. Maybe something like that would work here as well?  
> 
> I don't think that works for resets.
> Besides, the driver doesn't need or use the reset anyway.
> 

Finally, related to the "resets" property, what should I do ?
 (a) Keep the property as not required an change the commit log
 (b) Set the property as required and live with a warning (Rob's suggestion)

Regards,
Hervé

-- 
Hervé Codina, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com