netdev - Re: [PATCH net-next v4 02/23] net: phy: add genphy_c45_read_eee

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Date:   Mon, 6 Feb 2023 16:42:57 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Oleksij Rempel <o.rempel@...gutronix.de>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Wei Fang <wei.fang@....com>,
        Heiner Kallweit <hkallweit1@...il.com>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Arun.Ramadoss@...rochip.com, intel-wired-lan@...ts.osuosl.org
Subject: Re: [PATCH net-next v4 02/23] net: phy: add
 genphy_c45_read_eee_abilities() function

On Mon, Feb 06, 2023 at 01:22:46PM +0200, Vladimir Oltean wrote:
> On Mon, Feb 06, 2023 at 11:49:55AM +0100, Oleksij Rempel wrote:
> > > Why stop at 10GBase-KR? Register 3.20 defines EEE abilities up to 100G
> > > (for speeds >10G, there seem to be 2 modes, "deep sleep" or "fast wake",
> > > with "deep sleep" being essentially equivalent to the only mode
> > > available for <=10G modes).
> > 
> > Hm,
> > 
> > If i take only deep sleep, missing modes are:
> > 3.20.13 100GBASE-R deep sleep
> >        family of Physical Layer devices using 100GBASE-R encoding:
> >        100000baseCR4_Full
> >        100000baseKR4_Full
> >        100000baseCR10_Full (missing)
> >        100000baseSR4_Full
> >        100000baseSR10_Full (missing)
> >        100000baseLR4_ER4_Full
> > 
> > 3.20.11 25GBASE-R deep sleep
> >        family of Physical Layer devices using 25GBASE-R encoding:
> >        25000baseCR_Full
> >        25000baseER_Full (missing)
> >        25000baseKR_Full
> >        25000baseLR_Full (missing)
> >        25000baseSR_Full
> > 
> > 3.20.9 40GBASE-R deep sleep
> >        family of Physical Layer devices using 40GBASE-R encoding:
> >        40000baseKR4_Full
> >        40000baseCR4_Full
> >        40000baseSR4_Full
> >        40000baseLR4_Full
> > 
> > 3.20.7 40GBASE-T
> >        40000baseT_Full (missing)
> > 
> > I have no experience with modes > 1Gbit. Do all of them correct? What
> > should we do with missing modes? Or may be it make sense to implement >
> > 10G modes separately?
> 
> Given the fact that UAPI needs an extension to cover supported/advertisement
> bits > 31, I think it makes sense to add these separately. I had not
> realized this when I commented on this patch. I don't think we want the
> kernel to advertise EEE for some link modes without user space seeing it.

We also don't currently support any PHYs which do more than 10G. So i
don't see any need for 40GB and above at the moment.

      Andrew