linux-kernel - Re: [PATCH v4 1/5] dt-bindings: PCI: add snps,dw-pcie.yaml

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Date:   Sun, 18 Jul 2021 11:59:16 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     Rob Herring <robh@...nel.org>
Cc:     linuxarm@...wei.com, mauro.chehab@...wei.com,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Jingoo Han <jingoohan1@...il.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v4 1/5] dt-bindings: PCI: add snps,dw-pcie.yaml

Em Thu, 15 Jul 2021 11:23:37 -0600
Rob Herring <robh@...nel.org> escreveu:

> On Tue, Jul 13, 2021 at 01:17:51PM +0200, Mauro Carvalho Chehab wrote:
> > Currently, the designware schema is defined on a text file:
> > 	designware-pcie.txt
> > 
> > Convert the pci-bus part into a schema.
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> > ---
> >  .../devicetree/bindings/pci/snps,dw-pcie.yaml | 96 +++++++++++++++++++
> >  MAINTAINERS                                   |  1 +
> >  2 files changed, 97 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
> > new file mode 100644
> > index 000000000000..fd372d715ab4
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/pci/snps,dw-pcie.yaml
> > @@ -0,0 +1,96 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/pci/snps,dw-pcie.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Synopsys DesignWare PCIe interface
> > +
> > +maintainers:
> > +  - Jingoo Han <jingoohan1@...il.com>
> > +  - Gustavo Pimentel <gustavo.pimentel@...opsys.com>
> > +
> > +description: |
> > +  Synopsys DesignWare PCIe host controller
> > +
> > +allOf:
> > +  - $ref: /schemas/pci/pci-bus.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    anyOf:
> > +      - {}
> > +      - const: snps,dw-pcie
> > +
> > +  reg:
> > +    description: |
> > +      It should contain Data Bus Interface (dbi) and config registers for all
> > +      versions.
> > +      For designware core version >= 4.80, it may contain ATU address space.
> > +    minItems: 2
> > +    maxItems: 4
> > +
> > +  reg-names:
> > +    minItems: 2
> > +    maxItems: 4
> > +    items:
> > +      enum: [dbi, dbi2, config, atu, addr_space, app, elbi, mgmt]  
> 
> Isn't 'config' only for host and 'addr_space' only for endpoint?

The problem on enforcing an enum here is that severa *.dts files violate it. 
In the specific case of 'addr_space', there is (are?) place(s) where the wrong
compatible was used, like on arch/arm/boot/dts/artpec6.dtsi:

	pcie: pcie@...50000 {
		compatible = "axis,artpec6-pcie", "snps,dw-pcie";
		reg = <0xf8050000 0x2000
		       0xf8040000 0x1000
		       0xc0000000 0x2000>;
		reg-names = "dbi", "phy", "config";
		#address-cells = <3>;
		#size-cells = <2>;
		device_type = "pci";
			  /* downstream I/O */
		ranges = <0x81000000 0 0 0xc0002000 0 0x00010000
			  /* non-prefetchable memory */
			  0x82000000 0 0xc0012000 0xc0012000 0 0x1ffee000>;
		num-lanes = <2>;
		bus-range = <0x00 0xff>;
		interrupts = <GIC_SPI 148 IRQ_TYPE_LEVEL_HIGH>;
		interrupt-names = "msi";
		#interrupt-cells = <1>;
		interrupt-map-mask = <0 0 0 0x7>;
		interrupt-map = <0 0 0 1 &intc GIC_SPI 144 IRQ_TYPE_LEVEL_HIGH>,
				<0 0 0 2 &intc GIC_SPI 145 IRQ_TYPE_LEVEL_HIGH>,
				<0 0 0 3 &intc GIC_SPI 146 IRQ_TYPE_LEVEL_HIGH>,
				<0 0 0 4 &intc GIC_SPI 147 IRQ_TYPE_LEVEL_HIGH>;
		axis,syscon-pcie = <&syscon>;
		status = "disabled";
	};

	pcie_ep: pcie_ep@...50000 {
		compatible = "axis,artpec6-pcie-ep", "snps,dw-pcie";
		reg = <0xf8050000 0x2000
		       0xf8051000 0x2000
		       0xf8040000 0x1000
		       0xc0000000 0x20000000>;
		reg-names = "dbi", "dbi2", "phy", "addr_space";
		num-ib-windows = <6>;
		num-ob-windows = <2>;
		num-lanes = <2>;
		axis,syscon-pcie = <&syscon>;
		status = "disabled";
	};

(funny enough, this is not generating warnings here).

Btw, besides the above, there are some DTS that use something different
from what's there at the enum:


	$ make CROSS_COMPILE=aarch64-linux-gnu- ARCH=arm64 dtbs_check 2>&1 |tee dtbs_check.log
	$ grep "\['dbi', 'dbi2', 'config', 'atu', 'app', 'elbi', 'mgmt'\]" dtbs_check.log|sed "s,From schema:,,"|cut -d: -f 2-|cut -d' ' -f 4-|sort|uniq -c|sort -n -r
	     51 'ctrl' is not one of ['dbi', 'dbi2', 'config', 'atu', 'app', 'elbi', 'mgmt']
	     44 'parf' is not one of ['dbi', 'dbi2', 'config', 'atu', 'app', 'elbi', 'mgmt']
	     18 'cfg' is not one of ['dbi', 'dbi2', 'config', 'atu', 'app', 'elbi', 'mgmt']
	      4 'link' is not one of ['dbi', 'dbi2', 'config', 'atu', 'app', 'elbi', 'mgmt']

In order to use an enum and not having warnings, the enum should be 
instead:

	reg-names:
	  minItems: 2
	  maxItems: 4
	  items:
	    enum: [dbi, dbi2, config, atu, app, elbi, mgmt, ctrl, parf, cfg, link]  


Thanks,
Mauro