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From:   Rob Herring <robh@kernel.org>
Date:   Tue, 18 Dec 2018 15:10:43 -0600
Message-ID: <CAL_JsqJb24ZpM7qQfy_F7RUVEGyceBAXOndbZcTMh3a__k38UQ@mail.gmail.com>
Subject: Re: [PATCH v3 3/3] PCI: imx6: Add support for i.MX8MQ
To:     Leonard Crestez <leonard.crestez@nxp.com>
Cc:     Andrey Smirnov <andrew.smirnov@gmail.com>,
        Lucas Stach <l.stach@pengutronix.de>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Fabio Estevam <fabio.estevam@nxp.com>,
        Chris Healy <cphealy@gmail.com>,
        Dong Aisheng <aisheng.dong@nxp.com>,
        Richard Zhu <hongxing.zhu@nxp.com>, devicetree@vger.kernel.org,
        NXP Linux Team <linux-imx@nxp.com>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-pci@vger.kernel.org
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On Tue, Dec 18, 2018 at 12:09 PM Leonard Crestez
<leonard.crestez@nxp.com> wrote:
>
> On 12/18/2018 5:15 PM, Rob Herring wrote:
> > On Mon, Dec 17, 2018 at 08:07:02PM -0800, Andrey Smirnov wrote:
> >> Add code needed to support i.MX8MQ variant.
> >>
> >> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> >> Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
>
> >> --- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> >> +++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.txt
> >>
> >> +Additional required properties for imx8mq-pcie:
> >> +- fsl,controller-id: Logical ID of a given PCIE controller. PCIE1 is 0, PCIE2 is 1;
> >> +
> >
> > Remove this.
> >
> > If GPR register offset is what you need, then put that into DT.
> > Typically, we'd have a property with iomuxc phandle and offset.
>
> This series initially added explicit offsets but I suggested a single
> "controller-id" because:
>   * There are multiple bit and byte offsets
>   * Other imx8 SOCs also have 2x pcie with other bit/byte offsets
>
> Hiding this behind a compatible string and single "controller-id" seem
> preferable to elaborating register maps in dt bindings. It also makes
> upgrades simpler: if features are added which use other bits there is no
> need to describe them in DT and deal with compatibility headaches.

You already have an id for the controllers: the address. Use that if
you don't want to put the register offsets in DT.

Rob