netdev - Re: [PATCH RFC net] net: dsa: mv88e6xxx: allow use of PHYs on CPU and DSA ports

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Message-ID: <Ya92klnTqoUpFvpo@shell.armlinux.org.uk>
Date:   Tue, 7 Dec 2021 14:58:26 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Martyn Welch <martyn.welch@...labora.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org
Subject: Re: [PATCH RFC net] net: dsa: mv88e6xxx: allow use of PHYs on CPU
 and DSA ports

On Tue, Dec 07, 2021 at 03:54:37PM +0100, Andrew Lunn wrote:
> On Tue, Dec 07, 2021 at 10:59:19AM +0000, Russell King (Oracle) wrote:
> > Martyn Welch reports that his CPU port is unable to link where it has
> > been necessary to use one of the switch ports with an internal PHY for
> > the CPU port. The reason behind this is the port control register is
> > left forcing the link down, preventing traffic flow.
> > 
> > This occurs because during initialisation, phylink expects the link to
> > be down, and DSA forces the link down by synthesising a call to the
> > DSA drivers phylink_mac_link_down() method, but we don't touch the
> > forced-link state when we later reconfigure the port.
> > 
> > Resolve this by also unforcing the link state when we are operating in
> > PHY mode and the PPU is set to poll the PHY to retrieve link status
> > information.
> > 
> > Reported-by: Martyn Welch <martyn.welch@...labora.com>
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
> 
> Hi Russell
> 
> It would be good to have a Fixes: tag here, to help with back porting.

Oh, I thought this was a new development, not a regression. Do you have
a pointer to the earlier bits of the thread please, e.g. the message ID
of the original report.

Thanks.

> The concept looks good, and i see you now have a Tested-by:, so with
> the fixup applied i think you are good to go. Please add my
> Reviewed-by: to the next version.

Will do.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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