linux-kernel - Re: [PATCH v4 1/4] dt-bindings: net: phy: Add support for NXP TJA11xx

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Message-ID: <20200317115626.4ncavxdcw4wu5zgc@pengutronix.de>
Date:   Tue, 17 Mar 2020 12:56:27 +0100
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>, Mark Rutland <mark.rutland@....com>,
        Marek Vasut <marex@...x.de>, devicetree@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        David Jander <david@...tonic.nl>,
        "David S. Miller" <davem@...emloft.net>,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [PATCH v4 1/4] dt-bindings: net: phy: Add support for NXP TJA11xx

On Fri, Mar 13, 2020 at 07:53:27PM +0100, Oleksij Rempel wrote:
> On Fri, Mar 13, 2020 at 11:20:35AM -0700, Florian Fainelli wrote:
> > 
> > 
> > On 3/13/2020 11:16 AM, Oleksij Rempel wrote:
> > > On Fri, Mar 13, 2020 at 07:10:56PM +0100, Andrew Lunn wrote:
> > >>>> diff --git a/Documentation/devicetree/bindings/net/nxp,tja11xx.yaml b/Documentation/devicetree/bindings/net/nxp,tja11xx.yaml
> > >>>> new file mode 100644
> > >>>> index 000000000000..42be0255512b
> > >>>> --- /dev/null
> > >>>> +++ b/Documentation/devicetree/bindings/net/nxp,tja11xx.yaml
> > >>>> @@ -0,0 +1,61 @@
> > >>>> +# SPDX-License-Identifier: GPL-2.0+
> > >>>> +%YAML 1.2
> > >>>> +---
> > >>>> +$id: http://devicetree.org/schemas/net/nxp,tja11xx.yaml#
> > >>>> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > >>>> +
> > >>>> +title: NXP TJA11xx PHY
> > >>>> +
> > >>>> +maintainers:
> > >>>> +  - Andrew Lunn <andrew@...n.ch>
> > >>>> +  - Florian Fainelli <f.fainelli@...il.com>
> > >>>> +  - Heiner Kallweit <hkallweit1@...il.com>
> > >>>> +
> > >>>> +description:
> > >>>> +  Bindings for NXP TJA11xx automotive PHYs
> > >>>> +
> > >>>> +allOf:
> > >>>> +  - $ref: ethernet-phy.yaml#
> > >>>> +
> > >>>> +patternProperties:
> > >>>> +  "^ethernet-phy@[0-9a-f]+$":
> > >>>> +    type: object
> > >>>> +    description: |
> > >>>> +      Some packages have multiple PHYs. Secondary PHY should be defines as
> > >>>> +      subnode of the first (parent) PHY.
> > >>>
> > >>>
> > >>> There are QSGMII PHYs which have 4 PHYs embedded and AFAICT they are
> > >>> defined as 4 separate Ethernet PHY nodes and this would not be quite a
> > >>> big stretch to represent them that way compared to how they are.
> > >>>
> > >>> I would recommend doing the same thing and not bend the MDIO framework
> > >>> to support the registration of "nested" Ethernet PHY nodes.
> > >>
> > >> Hi Florian
> > >>
> > >> The issue here is the missing PHY ID in the secondary PHY. Because of
> > >> that, the secondary does not probe in the normal way. We need the
> > >> primary to be involved to some degree. It needs to register it. What
> > >> i'm not so clear on is if it just needs to register it, or if these
> > >> sub nodes are actually needed, given the current code.
> > > 
> > > There are a bit more dependencies:
> > > - PHY0 is responsible for health monitoring. If some thing wrong, it may
> > >   shut down complete chip.
> > > - We have shared reset. It make no sense to probe PHY1 before PHY0 with
> > >   more controlling options will be probed
> > > - It is possible bat dangerous to use PHY1 without PHY0.
> > 
> > probing is a software problem though. If we want to describe the PHY
> > package more correctly, we should be using a container node, something
> > like this maybe:
> >
> > phy-package {
> > 	compatible = "nxp,tja1102";
> > 
> > 	ethernet-phy@4 {
> > 		reg = <4>;
> > 	};
> > 
> > 	ethernet-phy@5 {
> > 		reg = <5>;
> > 	};
> > };
> 
> Yes, this is almost the same as it is currently done:
> 
> phy-package {
> 	reg = <4>;
>  
>  	ethernet-phy@5 {
>  		reg = <5>;
>  	};
> };
> 
> Because the primary PHY0 can be autodetected by the bus scan.
> But I have nothing against your suggestions. Please, some one should say the
> last word here, how exactly it should be implemented?

ping,

Regards,
Oleksij
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