linux-kernel - Re: [PATCH v4 05/12] Documentation: net: phy: Add phy-is-internal binding

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Message-ID: <20170810002041.GA10776@lunn.ch>
Date:   Thu, 10 Aug 2017 02:20:41 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     David Wu <david.wu@...k-chips.com>, davem@...emloft.net,
        heiko@...ech.de, robh+dt@...nel.org, mark.rutland@....com,
        catalin.marinas@....com, will.deacon@....com, olof@...om.net,
        linux@...linux.org.uk, arnd@...db.de, peppe.cavallaro@...com,
        alexandre.torgue@...com, huangtao@...k-chips.com,
        hwg@...k-chips.com, netdev@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 05/12] Documentation: net: phy: Add phy-is-internal
 binding

On Wed, Aug 09, 2017 at 03:47:34PM -0700, Florian Fainelli wrote:
> On August 9, 2017 5:10:30 AM PDT, David Wu <david.wu@...k-chips.com> wrote:
> >Add the documentation for internal phy. A boolean property
> >indicates that a internal phy will be used.
> >
> >Signed-off-by: David Wu <david.wu@...k-chips.com>
> >---
> > Documentation/devicetree/bindings/net/phy.txt | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> >diff --git a/Documentation/devicetree/bindings/net/phy.txt
> >b/Documentation/devicetree/bindings/net/phy.txt
> >index b558576..942c892 100644
> >--- a/Documentation/devicetree/bindings/net/phy.txt
> >+++ b/Documentation/devicetree/bindings/net/phy.txt
> >@@ -52,6 +52,9 @@ Optional Properties:
> >   Mark the corresponding energy efficient ethernet mode as broken and
> >   request the ethernet to stop advertising it.
> > 
> >+- phy-is-internal: If set, indicates that phy will connect to the MAC
> >as a
> >+  internal phy.
> 
> Something along the lines of:
> 
> If set, indicates that the PHY is integrated into the same physical package as the Ethernet MAC.

Hi Florian, David.

I'm happy with the property name. But i think the text needs more
description. We deal with Ethernet switches with integrated PHYs. Yet
for us, this property is unneeded.

Seeing this property means some bit of software needs to ensure the
internal PHY should be used, when given the choice between an internal
and external PHY. So i would say something like:

    If set, indicates that the PHY is integrated into the same
    physical package as the Ethernet MAC. If needed, muxers should be
    configured to ensure the internal PHY is used. The absence of this
    property indicates the muxers should be configured so that the
    external PHY is used.

This last part is important. If the bootloader has set the internal
PHY to be used, you need to reset it. Otherwise we are going to get
into a mess sometime later and need to add a phy-is-external property.

     Andrew