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Date:   Wed, 4 May 2022 08:53:17 -0500
From:   Rob Herring <robh@kernel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Herve Codina <herve.codina@bootlin.com>,
        Marek Vasut <marek.vasut+renesas@gmail.com>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        Magnus Damm <magnus.damm@gmail.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        linux-pci <linux-pci@vger.kernel.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Sergey Shtylyov <s.shtylyov@omp.ru>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        Clement Leger <clement.leger@bootlin.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>
Subject: Re: [PATCH v5 2/6] dt-bindings: PCI: renesas,pci-rcar-gen2: Add
 device tree support for r9a06g032
Message-ID: <YnKFTVFaYO9uk2m0@robh.at.kernel.org>
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On Tue, May 03, 2022 at 11:29:53AM +0200, Krzysztof Kozlowski 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?

IMO, we should move away from doing that for clocks. It's a guaranteed 
ABI break.

Rob