linux-kernel - Re: [PATCH v2 2/2] dt-bindings: PCI: Convert PCIe Host/Endpoint in Cadence platform to DT schema

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Date:   Mon, 24 Feb 2020 09:26:38 -0600
From:   Rob Herring <robh@...nel.org>
To:     Kishon Vijay Abraham I <kishon@...com>
Cc:     Tom Joseph <tjoseph@...ence.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <amurray@...goodpenguin.co.uk>,
        Mark Rutland <mark.rutland@....com>,
        PCI <linux-pci@...r.kernel.org>, devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] dt-bindings: PCI: Convert PCIe Host/Endpoint in
 Cadence platform to DT schema

On Mon, Feb 24, 2020 at 4:14 AM Kishon Vijay Abraham I <kishon@...com> wrote:
>
> Hi Rob,
>
> On 20/02/20 2:02 am, Rob Herring wrote:
> > On Mon, Feb 17, 2020 at 04:45:19PM +0530, Kishon Vijay Abraham I wrote:
> >> Include Cadence core DT schema and define the Cadence platform DT schema
> >> for both Host and Endpoint mode. Note: The Cadence core DT schema could
> >> be included for other platforms using Cadence PCIe core.
> >>
> >> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> >> ---
> >>  .../bindings/pci/cdns,cdns-pcie-ep.txt        | 27 -------
> >>  .../bindings/pci/cdns,cdns-pcie-ep.yaml       | 48 ++++++++++++
> >>  .../bindings/pci/cdns,cdns-pcie-host.txt      | 66 ----------------
> >>  .../bindings/pci/cdns,cdns-pcie-host.yaml     | 76 +++++++++++++++++++
> >>  MAINTAINERS                                   |  2 +-
> >>  5 files changed, 125 insertions(+), 94 deletions(-)
> >>  delete mode 100644 Documentation/devicetree/bindings/pci/cdns,cdns-pcie-ep.txt
> >>  create mode 100644 Documentation/devicetree/bindings/pci/cdns,cdns-pcie-ep.yaml
> >>  delete mode 100644 Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.txt
> >>  create mode 100644 Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
> >
> >
> >> diff --git a/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
> >> new file mode 100644
> >> index 000000000000..2f605297f862
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/pci/cdns,cdns-pcie-host.yaml
> >> @@ -0,0 +1,76 @@
> >> +# SPDX-License-Identifier: GPL-2.0-only
> >> +%YAML 1.2
> >> +---
> >> +$id: http://devicetree.org/schemas/pci/cdns,cdns-pcie-host.yaml#
> >> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> >> +
> >> +title: Cadence PCIe host controller
> >> +
> >> +maintainers:
> >> +  - Tom Joseph <tjoseph@...ence.com>
> >> +
> >> +allOf:
> >> +  - $ref: /schemas/pci/pci-bus.yaml#
> >> +  - $ref: "cdns-pcie-host.yaml#"
> >> +
> >> +properties:
> >> +  compatible:
> >> +    const: cdns,cdns-pcie-host
> >> +
> >> +  reg:
> >> +    maxItems: 3
> >> +
> >> +  reg-names:
> >> +    items:
> >> +      - const: reg
> >> +      - const: cfg
> >> +      - const: mem
> >> +
> >> +  msi-parent: true
> >> +
> >> +required:
> >> +  - reg
> >> +  - reg-names
> >> +
> >> +examples:
> >> +  - |
> >> +    bus {
> >> +        #address-cells = <2>;
> >> +        #size-cells = <2>;
> >> +
> >> +        pcie@...00000 {
> >> +            compatible = "cdns,cdns-pcie-host";
> >> +            device_type = "pci";
> >> +            #address-cells = <3>;
> >> +            #size-cells = <2>;
> >> +            bus-range = <0x0 0xff>;
> >> +            linux,pci-domain = <0>;
> >> +            cdns,max-outbound-regions = <16>;
> >> +            cdns,no-bar-match-nbits = <32>;
> >
> >> +            vendor-id = /bits/ 16 <0x17cd>;
> >> +            device-id = /bits/ 16 <0x0200>;
> >
> > Please make these 32-bit as that is what the spec says.
>
> Can you clarify this is mentioned in which spec? PCI spec has both of
> these 16 bits and I checked the PCI binding doc but couldn't spot the
> size of these fields.
>
> [1] -> https://www.devicetree.org/open-firmware/bindings/pci/pci2_1.pdf

Section 4.1.2.1. The key point is the type is 'encode-int' which means
32-bit. Keep in mind, that 16-bits was not a defined type when this
spec was written. We added that for FDT.

Also, look at other instances of reading 'vendor-id' in the kernel.

Rob