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From: Andrew Lunn <andrew@lunn.ch>
To: Heiner Kallweit <hkallweit1@gmail.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
	David Miller <davem@davemloft.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next] net: phy: aquantia: add downshift support
Date: Thu, 21 Mar 2019 09:38:27 +0100	[thread overview]
Message-ID: <20190321083827.GD2900@lunn.ch> (raw)
In-Reply-To: <1d3111d4-5af9-0611-8642-b5f29067651e@gmail.com>

On Wed, Mar 20, 2019 at 10:15:10PM +0100, Heiner Kallweit wrote:
> Aquantia PHY's of the AQR107 family support the downshift feature.
> Add support for it as standard PHY tunable so that it can be controlled
> via ethtool.
> The AQCS109 supports a proprietary 2-pair 1Gbps mode. If two such PHY's
> are connected to each other with a 2-pair cable, they may not be able
> to establish a link if both advertise modes >= 1Gbps. Therefore enable
> downshift per default on this model.

Hi Heiner

Is there any way to know it has done a downshift?

Florian said the Intel drivers print a message when they downshift. It
could be interesting to know, especially when a PHY goes from 1G to
100M.

Even for a downshift to 1000Base-T2, i'm guessing for most use cases,
this means the cable is partially broken, and it serves as an early
warning it needs replacing.

	Andrew

  parent reply	other threads:[~2019-03-21  8:38 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-20 21:15 [PATCH net-next] net: phy: aquantia: add downshift support Heiner Kallweit
2019-03-20 21:27 ` Florian Fainelli
2019-03-21  8:38 ` Andrew Lunn [this message]
2019-03-21 16:30   ` David Miller
2019-03-21 16:36     ` Florian Fainelli
2019-03-21 18:49   ` Heiner Kallweit

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