netdev - Re: [PATCH ethtool 2/2] Ethtool: Implements PHY Loopback

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Date:   Mon, 28 Nov 2016 09:56:04 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     "Allan W. Nielsen" <allan.nielsen@...rosemi.com>,
        netdev@...r.kernel.org
Cc:     linville@...driver.com, andrew@...n.ch,
        raju.lakkaraju@...rosemi.com
Subject: Re: [PATCH ethtool 2/2] Ethtool: Implements PHY Loopback

On 11/28/2016 05:25 AM, Allan W. Nielsen wrote:
> From: Raju Lakkaraju <Raju.Lakkaraju@...rosemi.com>
> 
> Add loopback in ethtool tunables to access PHY drivers.
> 
> Ethtool Help: ethtool -h for PHY tunables
>     ethtool --set-phy-tunable DEVNAME      Set PHY tunable
>                 [ loopback off|near|far|extn ]
>     ethtool --get-phy-tunable DEVNAME      Get PHY tunable
>                 [ loopback ]
> 
> Ethtool ex:
>   ethtool --set-phy-tunable eth0 loopback near
>   ethtool --set-phy-tunable eth0 loopback far
>   ethtool --set-phy-tunable eth0 loopback extn
>   ethtool --set-phy-tunable eth0 loopback off
> 
>   ethtool --get-phy-tunable eth0 loopback
> 
> Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@...rosemi.com>
> Signed-off-by: Allan W. Nielsen <allan.nielsen@...rosemi.com>
> ---

> +Near-End Loopback:
> +Transmitted data (TXD) is looped back in the PCS block onto the receive data
> +signal (RXD). When Near-End loopback enable, no data is transmitted over
> +the network. no data receive from the network.

This is also known as the local loopback test mode, right?

> +
> +Far-End Loopback:
> +This loopback is a special test mode to allow testing the PHY from link
> +partner side. In this mode data that is received from the link partner pass
> +through the PHY's receiver, looped back on the MII and transmitted back to
> +the link partner.

And this is the remote loopback mode.


> +
> +External Loopback:
> +An RJ45 loopback cable can be used to route the transmit signals an the
> +output of the trnsformer back to the receiver inputs and this loopback will
> +work at either 10 or 100 or 1000 Mbps speed.
> +RJ45 Loopback cable created by conncting pin 1 to pin 3 and connecting pin
> +2 to pin 6.

OK, this name makes sense to me, but for the two other names, we need to
use a terminology that is clearer to the reader and/or people familiar
and targeted at using this feature (e.g: in a lab or during manufacturing).
-- 
Florian