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Date:   Wed, 12 Aug 2020 17:22:32 +0100
From:   Russell King - ARM Linux admin <>
To:     Marek BehĂșn <>
Cc:     Andrew Lunn <>,
        Maxime Chevallier <>,
        Baruch Siach <>,
        Chris Healy <>,
        Florian Fainelli <>,
Subject: Re: [PATCH RFC russell-king 3/4] net: phy: marvell10g: change
 MACTYPE according to phydev->interface

On Wed, Aug 12, 2020 at 06:13:33PM +0200, Marek BehĂșn wrote:
> The MACTYPE is not being lost. But changing it requires Port Software
> Reset, which resets the link, so it cannot be done for example in
> read_status.

Wouldn't the right place to configure it be in the config_init()
method - which is called once we have a MAC attaching to the PHY?
As I mentioned, if we had a way to pass the MAC interface supported
mask into phylib, config_init() could then use that to determine what
to do.

> I think the MACTYPE should be set sometime during PHY initialisation,
> and only once: either to XFI with rate matching, if the underlying MAC
> does not support lower modes, or to 10gbase-r/2500base-x/sgmii mode, if
> the underlying MAC supports only slower modes than 10G.

Yes - only changing the MAC type if we have good reason to do so to
support other rates.

There is a related problem however.  Note that if you have an 88x3310
(non-P) in the SFP, then when rate matching is enabled, the PHY will
_not_ generate pause frames, and the PHY expects the MAC to be
configured to pace itself to the slower speed.  I don't believe we
have support in MACs for that, but phylib and therefore phylink
provides the information:

	interface - 10GBASE-R
	speed - media speed
	pause - media pause modes

So, if speed != SPEED_10000 and there are no pause modes, we should,
for the sake of the entire link, pace the MAC to the media speed by
controlling its egress rate.

RMK's Patch system:
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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