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Message-ID: <20210506151839.GA322729@robh.at.kernel.org>
Date: Thu, 6 May 2021 10:18:39 -0500
From: Rob Herring <robh@...nel.org>
To: Sergio Paracuellos <sergio.paracuellos@...il.com>
Cc: devicetree@...r.kernel.org, linux-staging@...ts.linux.dev,
gregkh@...uxfoundation.org, neil@...wn.name,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dt-bindings: staging: mt7621-pci: PCIe binding
documentation for MT76721 SoCs
On Sat, May 01, 2021 at 03:36:46PM +0200, Sergio Paracuellos wrote:
> Add device tree binding documentation for PCIe in MT7621 SoCs.
>
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>
> ---
>
> Hi Rob,
>
> Some concerns here. I was not be able to found any case similar to
> this binding where sub-nodes describing each pcie port interface
> are needed. I added them to the 'examples' directly without saying
> anything about properties in any other place since its properties
> seems to be covered in 'pci-bus.yaml' schema definition. I don't
> know if this is the way, I have checked against schema and I noticed
> I am forced to add 'device_type' property in each subnode because
> schema checker complains that this is mandatory. So I have added
> it and schema is properly being validated:
>
> Before add the 'device_type' in each subnode:
> /home/sergio/staging/Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.example.dt.yaml: pcie@0,0: 'device_type' is a required property
> >From schema: /home/sergio/.local/lib/python3.9/site-packages/dtschema/schemas/pci/pci-bus.yaml
> /home/sergio/staging/Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.example.dt.yaml: pcie@1,0: 'device_type' is a required property
> >From schema: /home/sergio/.local/lib/python3.9/site-packages/dtschema/schemas/pci/pci-bus.yaml
> /home/sergio/staging/Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.example.dt.yaml: pcie@2,0: 'device_type' is a required property
> >From schema: /home/sergio/.local/lib/python3.9/site-packages/dtschema/schemas/pci/pci-bus.yaml
Each port is a PCI bridge, right? If so, then 'pcie' for the node name
and 'device_type = "pci";' are correct.
>
> After adding it:
> CHKDT Documentation/devicetree/bindings/processed-schema-examples.json
Validates all the schema
> SCHEMA Documentation/devicetree/bindings/processed-schema-examples.json
Preprocesses all the schema
> DTEX Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.example.dts
Extracts the example to dts file
> DTC Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.example.dt.yaml
Converts the example to yaml
> CHECK Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.example.dt.yaml
Runs the checks.
>
> Looks a bit redundant and maybe I am doing something wrong...
>
> Thanks in advance for clarification.
>
> Best regards,
> Sergio Paracuellos
>
>
> .../bindings/pci/mediatek,mt7621-pci.yaml | 144 ++++++++++++++++++
> .../mt7621-pci/mediatek,mt7621-pci.txt | 104 -------------
> 2 files changed, 144 insertions(+), 104 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.yaml
> delete mode 100644 drivers/staging/mt7621-pci/mediatek,mt7621-pci.txt
>
> diff --git a/Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.yaml b/Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.yaml
> new file mode 100644
> index 000000000000..9c1d05d929a2
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pci/mediatek,mt7621-pci.yaml
> @@ -0,0 +1,144 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/pci/mediatek,mt7621-pci.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: MediaTek MT7621 PCIe controller
> +
> +maintainers:
> + - Sergio Paracuellos <sergio.paracuellos@...il.com>
> +
> +description: |+
> + MediaTek MT7621 PCIe subsys supports single Root complex (RC)
> + with 3 Root Ports. Each Root Ports supports a Gen1 1-lane Link
> +
> +allOf:
> + - $ref: /schemas/pci/pci-bus.yaml#
> +
> +properties:
> + compatible:
> + const: mediatek,mt7621-pci
> +
> + reg:
> + items:
> + - description: host-pci bridge registers
> + - description: pcie port 0 RC control registers
> + - description: pcie port 1 RC control registers
> + - description: pcie port 2 RC control registers
Are these config space registers or MT7621 specific?
> +
> + ranges:
> + maxItems: 2
> +
> + interrupts:
> + maxItems: 3
What are the 3 interrupts?
> +
> + resets:
> + items:
> + - description: pcie port 0 reset.
> + - description: pcie port 1 reset.
> + - description: pcie port 2 reset.
This and clocks should perhaps be in each child node.
> +
> + reset-names:
> + items:
> + - const: pcie0
> + - const: pcie1
> + - const: pcie2
> +
> + clocks:
> + items:
> + - description: pcie port 0 clock.
> + - description: pcie port 1 clock.
> + - description: pcie port 2 clock.
> +
> + clock-names:
> + items:
> + - const: pcie0
> + - const: pcie1
> + - const: pcie2
> +
> + phys:
> + items:
> + - description: Dual-ported phy for pcie port 0 and 1.
> + - description: Phy for pcie port 2.
> +
> + phy-names:
> + items:
> + - const: pcie-phy0
> + - const: pcie-phy2
> +
> +required:
> + - compatible
> + - reg
> + - ranges
> + - interrupts
> + - resets
> + - reset-names
> + - clocks
> + - clock-names
> + - phys
> + - phy-names
> + - reset-gpios
> +
> +unevaluatedProperties: false
> +
> +examples:
> + - |
> + #include <dt-bindings/gpio/gpio.h>
> + #include <dt-bindings/interrupt-controller/mips-gic.h>
> +
> + pcie: pcie@...40000 {
> + compatible = "mediatek,mt7621-pci";
> + reg = <0x1e140000 0x100>,
> + <0x1e142000 0x100>,
> + <0x1e143000 0x100>,
> + <0x1e144000 0x100>;
> +
> + #address-cells = <3>;
> + #size-cells = <2>;
> + pinctrl-names = "default";
> + pinctrl-0 = <&pcie_pins>;
> + device_type = "pci";
> + bus-range = <0 255>;
That's the default, so not needed.
> + ranges = <0x02000000 0 0x00000000 0x60000000 0 0x10000000>, /* pci memory */
> + <0x01000000 0 0x00000000 0x1e160000 0 0x00010000>; /* io space */
> + interrupt-parent = <&gic>;
> + interrupts = <GIC_SHARED 4 IRQ_TYPE_LEVEL_HIGH>,
> + <GIC_SHARED 24 IRQ_TYPE_LEVEL_HIGH>,
> + <GIC_SHARED 25 IRQ_TYPE_LEVEL_HIGH>;
> + resets = <&rstctrl 24>, <&rstctrl 25>, <&rstctrl 26>;
> + reset-names = "pcie0", "pcie1", "pcie2";
> + clocks = <&clkctrl 24>, <&clkctrl 25>, <&clkctrl 26>;
> + clock-names = "pcie0", "pcie1", "pcie2";
> + phys = <&pcie0_phy 1>, <&pcie2_phy 0>;
> + phy-names = "pcie-phy0", "pcie-phy2";
> + reset-gpios = <&gpio 19 GPIO_ACTIVE_LOW>;
> +
> + pcie@0,0 {
> + reg = <0x0000 0 0 0 0>;
> + #address-cells = <3>;
> + #size-cells = <2>;
> + device_type = "pci";
> + ranges;
> + bus-range = <0x00 0xff>;
Besides being the default, I don't think this makes sense here as it
belongs in the parent unless you had some subset of bus numbers allowed
by the parent.
> + };
> +
> + pcie@1,0 {
> + reg = <0x0800 0 0 0 0>;
> + #address-cells = <3>;
> + #size-cells = <2>;
> + device_type = "pci";
> + ranges;
> + bus-range = <0x00 0xff>;
> + };
> +
> + pcie@2,0 {
> + reg = <0x1000 0 0 0 0>;
> + #address-cells = <3>;
> + #size-cells = <2>;
> + device_type = "pci";
> + ranges;
> + bus-range = <0x00 0xff>;
> + };
> + };
> +...
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