linux-kernel - Re: [PATCH 1/1] dt-bindings: net: mdio: Add negative patten match for child node

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Message-ID: <20240812-unmoving-viscosity-5f03dfd87f1f@spud>
Date: Mon, 12 Aug 2024 17:44:50 +0100
From: Conor Dooley <conor@...nel.org>
To: Frank Li <Frank.Li@....com>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Florian Fainelli <f.fainelli@...il.com>,
	"open list:ETHERNET PHY LIBRARY" <netdev@...r.kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@...r.kernel.org>,
	open list <linux-kernel@...r.kernel.org>, imx@...ts.linux.dev
Subject: Re: [PATCH 1/1] dt-bindings: net: mdio: Add negative patten match
 for child node

On Sun, Aug 11, 2024 at 11:11:14PM -0400, Frank Li wrote:
> mdio.yaml wrong parser mdio controller's address instead phy's address when
> mdio-mux exist.
> 
> For example:
> mdio-mux-emi1@54 {
> 	compatible = "mdio-mux-mmioreg", "mdio-mux";
> 
>         mdio@20 {
> 		reg = <0x20>;
> 		       ^^^ This is mdio controller register
> 
> 		ethernet-phy@2 {
> 			reg = <0x2>;
>                               ^^^ This phy's address
> 		};
> 	};
> };

I don't understand MDIO well enough to know the answer - does this
actually solve the problem? It seems to me that the problem is that
mdio.yaml is applied to the mdio-mux node because it matches the pattern
"^mdio(@.*)?" that applies the binding based on node-names. If the
properties in mdio.yaml do not apply to mdio muxes, then the binding
should not be applied and the patch here is only treating a symptom
rather than the actual problem.

From a quick check, I don't see any of the mdio-mux-mmioreg nodes using
the properties from mdio.yaml, so should the binding be applied to them
at all?

Cheers,
Conor.


FWIW, adding a $ after the ? in the pattern I linked would stop the
binding being applied to the mdio-mux nodes, but if something like that
were done, all mdio nodes would need to be checked to ensure they match
the new pattern...


> 
> Only phy's address is limited to 31 because MDIO bus defination.
> 
> But CHECK_DTBS report below warning:
> 
> arch/arm64/boot/dts/freescale/fsl-ls1043a-qds.dtb: mdio-mux-emi1@54:
> 	mdio@20:reg:0:0: 32 is greater than the maximum of 31
> 
> The reason is that "mdio@20" match "patternProperties: '@[0-9a-f]+$'" in
> mdio.yaml.
> 
> Change to '^(?!mdio@).*@[0-9a-f]+$' to avoid match parent's mdio
> controller's address.
> 
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
>  Documentation/devicetree/bindings/net/mdio.yaml | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/mdio.yaml b/Documentation/devicetree/bindings/net/mdio.yaml
> index a266ade918ca7..a7def3eb4674d 100644
> --- a/Documentation/devicetree/bindings/net/mdio.yaml
> +++ b/Documentation/devicetree/bindings/net/mdio.yaml
> @@ -59,7 +59,7 @@ properties:
>      type: boolean
>  
>  patternProperties:
> -  '@[0-9a-f]+$':
> +  '^(?!mdio@).*@[0-9a-f]+$':
>      type: object
>  
>      properties:
> -- 
> 2.34.1
> 

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