linux-kernel - Re: [PATCH v4 03/17] dt-bindings: PCI: dwc: Add phys/phy-names common properties

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Date:   Mon, 8 Aug 2022 09:58:56 -0600
From:   Rob Herring <robh@...nel.org>
To:     Serge Semin <fancer.lancer@...il.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Pavel Parkhomenko <Pavel.Parkhomenko@...kalelectronics.ru>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Frank Li <Frank.Li@....com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        PCI <linux-pci@...r.kernel.org>, devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 03/17] dt-bindings: PCI: dwc: Add phys/phy-names common properties

On Mon, Aug 8, 2022 at 4:36 AM Serge Semin <fancer.lancer@...il.com> wrote:
>
> On Mon, Aug 01, 2022 at 11:56:36AM -0600, Rob Herring wrote:
> > On Thu, Jul 28, 2022 at 05:34:13PM +0300, Serge Semin wrote:
> > > It's normal to have the DW PCIe RP/EP DT-nodes equipped with the explicit
> > > PHY phandle references. There can be up to 16 PHYs attach in accordance
> > > with the maximum number of supported PCIe lanes. Let's extend the common
> > > DW PCIe controller schema with the 'phys' and 'phy-names' properties
> > > definition. The PHY names are defined with the regexp pattern
> > > '^pcie([0-9]+|-?phy[0-9]*)?$' so to match the names currently supported by
> > > the DW PCIe platform drivers ("pcie": meson; "pciephy": qcom, imx6;
> > > "pcie-phy": uniphier, rockchip, spear13xx; "pcie": intel-gw; "pcie-phy%d":
> > > keystone, dra7xx; "pcie": histb, etc). Though the "pcie%d" format would
> > > the most preferable in this case.
> >
>
> > No phy-names is my preference. Some string plus an index is utterly
> > pointless. Oh well...
>
> Mine too, but we have no choice in this case since the named
> PHY-properties support has already been advertised by the platform
> drivers. This patch just provides the bindings for them. Just note
> the string patterns have been designed in a way to match these bindings.
>
> Anyway thanks for telling about the preferred option. Keeping that in
> mind I won't have doubts what approach to select for the new
> driver/bindings development.
>
> >
> > >
> > > Signed-off-by: Serge Semin <Sergey.Semin@...kalelectronics.ru>
> > >
> > > ---
> > >
> > > Changelog v3:
> > > - This is a new patch unpinned from the next one:
> > >   https://lore.kernel.org/linux-pci/20220503214638.1895-2-Sergey.Semin@baikalelectronics.ru/
> > >   by the Rob' request. (@Rob)
> > > ---
> > >  .../bindings/pci/snps,dw-pcie-common.yaml         | 15 +++++++++++++++
> > >  .../devicetree/bindings/pci/snps,dw-pcie-ep.yaml  |  3 +++
> > >  .../devicetree/bindings/pci/snps,dw-pcie.yaml     |  3 +++
> > >  3 files changed, 21 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
> > > index 3e992b653d12..627a5d6625ba 100644
> > > --- a/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
> > > +++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie-common.yaml
> > > @@ -17,6 +17,21 @@ description:
> > >  select: false
> > >
> > >  properties:
> > > +  phys:
> > > +    description:
> > > +      There can be up to the number of possible lanes PHYs specified.
> >
>
> > This needs something about being in order of lane number.
>
> Ok.
>
> >
> > > +      Obviously each specified PHY is supposed to be able to work in the
> > > +      PCIe mode with a speed implied by the DWC PCIe controller it is
> > > +      attached to.
> > > +    minItems: 1
> > > +    maxItems: 16
> > > +
> > > +  phy-names:
> > > +    minItems: 1
> > > +    maxItems: 16
> > > +    items:
> > > +      pattern: '^pcie([0-9]+|-?phy[0-9]*)?$'
> >
>
> > Please comment here that pcie[0-9] is the preferred form.
>
> What about a bit more sophisticated update?
> phy-names:
>   minItems: 1
>   maxItems: 16
>   oneOf:
>     - items:
>         pattern: '^pcie[0-9]+$'
>     - deprecated: true
>       items:
>         pattern: '^pcie(-?phy[0-9]*)?$'

Sure.

Rob