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Date:   Sun, 24 Feb 2019 15:34:49 +0000
From:   Russell King - ARM Linux admin <>
To:     Heiner Kallweit <>
Cc:     Andrew Lunn <>,
        Florian Fainelli <>,
        "" <>
Subject: Re: No traffic with Marvell switch and latest linux-next

On Sun, Feb 24, 2019 at 04:28:32PM +0100, Heiner Kallweit wrote:
> On 24.02.2019 16:15, Russell King - ARM Linux admin wrote:
> > On Sun, Feb 24, 2019 at 04:04:03PM +0100, Andrew Lunn wrote:
> >>> I think what's not correct is that phydev->autoneg is set
> >>> (by phy_device_create) for a fixed link.
> >>
> >> Fixed-link tries to emulate auto-neg:
> >>
> >>                 bmsr |= BMSR_LSTATUS | BMSR_ANEGCOMPLETE;
> >>
> >> Maybe it needs better emulation of auto-neg?
> > 
> > Or maybe it needs to represent a fixed-speed PHY by clearing bit 1.3
> > (BMSR_ANEGCAPABLE).  In any case, 0.12 (BMCR_ANENABLE) is not set,
> > so according to 802.3-2015, we should not be setting 1.5
> > 
> > However, swphy does try to emulate autonegotiation - we do have cases
> > where swphy is used in situations where the speed and duplex are not
> > fixed.  It returns an emulated link partner advertisement for the
> > current speed, which would suggest that we should set BMCR_ANENABLE.
> > 
> If we emulate auto-neg, then it's not needed to set the speed bits
> in BMCR. Also what just comes to my mind, certain speeds like 1000BaseT
> don't support forced mode. So we may have to go with auto-neg.


> To avoid the original issue it should be sufficient to copy
> supported -> advertising at a suited place.

Why bother - the software PHY emulation is an emulation to allow
existing userspace that pre-dates the ethtool API to get some link
parameters.  If we augment the PHY emulation in non-standard ways,
userspace will need to be updated to handle those non-standard
ways.  If userspace needs to be updated, why not just bite the
bullet and update to ethtool APIs rather than adding more
complication through an emulation layer?

RMK's Patch system:
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to 11.9Mbps down 500kbps up

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