linux-kernel - Re: [PATCH 4/4] dt-bindings: PCI: microchip,pcie-host: fix missing address translation property

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Message-ID: <20220816171652.GA2390778-robh@kernel.org>
Date:   Tue, 16 Aug 2022 11:16:52 -0600
From:   Rob Herring <robh@...nel.org>
To:     Conor.Dooley@...rochip.com
Cc:     krzysztof.kozlowski@...aro.org, mail@...chuod.ie,
        Daire.McNamara@...rochip.com, bhelgaas@...gle.com,
        krzysztof.kozlowski+dt@...aro.org, paul.walmsley@...ive.com,
        greentime.hu@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
        lpieralisi@...nel.org, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Subject: Re: [PATCH 4/4] dt-bindings: PCI: microchip,pcie-host: fix missing
 address translation property

On Fri, Aug 12, 2022 at 08:20:45AM +0000, Conor.Dooley@...rochip.com wrote:
> On 12/08/2022 08:52, Krzysztof Kozlowski wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > On 11/08/2022 23:33, Conor Dooley wrote:
> >> From: Conor Dooley <conor.dooley@...rochip.com>
> >>
> >> When the PCI controller node was added to the PolarFire SoC dtsi,
> >> dt-schema was not able to detect the presence of some undocumented
> >> properties due to how it handled unevaluatedProperties. v2022.08
> >> introduces better validation, producing the following error:
> >>
> >> arch/riscv/boot/dts/microchip/mpfs-polarberry.dtb: pcie@...0000000: Unevaluated properties are not allowed ('clock-names', 'microchip,axi-m-atr0' were unexpected)
> >>          From schema: Documentation/devicetree/bindings/pci/microchip,pcie-host.yaml
> >>
> >> Fixes: 528a5b1f2556 ("riscv: dts: microchip: add new peripherals to icicle kit device tree")
> >> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>
> >> ---
> >> I feel like there's a pretty good chance that this is not the way this
> >> should have been done and the property should be marked as deprecated
> >> but I don't know enough about PCI to answer that.
> > 
> > It seems bindings were added incomplete and now based on DTS (which did
> > not match bindings), we keep adding "missing" properties. I don't think
> > it is good. It creates a precedence where someone might intentionally
> > sneak limited bindings (without controversial property) and later claim
> > "I forgot to include foo,bar".
> 
> Yup, again pretty much the same thoughts as me. I don't think that, even
> if the property is valid, should be either named as it is or only work
> for translation table 0.
> 
> > 
> > Therefore the property should pass review just like it is newly added
> > property.
> 
> SGTM.
> 
> > 
> >> ---
> >>   .../devicetree/bindings/pci/microchip,pcie-host.yaml  | 11 +++++++++++
> >>   1 file changed, 11 insertions(+)
> >>
> >> diff --git a/Documentation/devicetree/bindings/pci/microchip,pcie-host.yaml b/Documentation/devicetree/bindings/pci/microchip,pcie-host.yaml
> >> index 9b123bcd034c..9ac34b33c4b2 100644
> >> --- a/Documentation/devicetree/bindings/pci/microchip,pcie-host.yaml
> >> +++ b/Documentation/devicetree/bindings/pci/microchip,pcie-host.yaml
> >> @@ -71,6 +71,17 @@ properties:
> >>     msi-parent:
> >>       description: MSI controller the device is capable of using.
> >>
> >> +  microchip,axi-m-atr0:
> > 
> > Name is not helping. If it is offset, add such suffix (see
> > brcm,iproc-pcie.yaml).
> > 
> > Unfortunately I don't know PCIe good enough to judge whether the
> > property makes any sense or some other ranges-style should be used.
> 
> Yup, I think it is similar to that. Except we have 4 tables rather
> than one.

Looks to me like dma-ranges is the answer.

Rob