linux-kernel - Re: [PATCH 1/1] net: phy: meson-gxl: Add generic dummy stubs for MMD register access

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Message-ID: <CAFXsbZppb5tDxR9tO7RN76=rt04MdAUU16HhyNizJBtAXtq+fg@mail.gmail.com>
Date:   Sun, 29 Jan 2023 13:28:12 -0800
From:   Chris Healy <cphealy@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
        neil.armstrong@...aro.org, khilman@...libre.com,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        jeremy.wang@...ogic.com, Chris Healy <healych@...zon.com>
Subject: Re: [PATCH 1/1] net: phy: meson-gxl: Add generic dummy stubs for MMD
 register access

On Sun, Jan 29, 2023 at 8:52 AM Andrew Lunn <andrew@...n.ch> wrote:
>
> On Sat, Jan 28, 2023 at 06:26:15PM -0800, Chris Healy wrote:
> > From: Chris Healy <healych@...zon.com>
> >
> > The Meson G12A Internal PHY does not support standard IEEE MMD extended
> > register access, therefore add generic dummy stubs to fail the read and
> > write MMD calls. This is necessary to prevent the core PHY code from
> > erroneously believing that EEE is supported by this PHY even though this
> > PHY does not support EEE, as MMD register access returns all FFFFs.
>
> Hi Chris
>
> This change in itself makes sense. But i wounder if we should also
> change phy_init_eee(). It reads the EEE Ability register. The 2018
> version of the standard indicates the top two bits are reserved and
> should be zero. We also don't have any PHY which supports 100GBase-R
> through to 100Base-TX. So a read of 0xffff suggests the PHY does not
> support EEE and returning -EPROTONOSUPPORT would be good.
>
This seems like a good change to make in phy_init_eee().  I should be
able to do this.  Can this be done in a subsequent patch or does this
need to be present to land this meson specific PHY patch?

>         Andrew