netdev - Re: Ethtool: advance phy debug support

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Message-ID: <843c25c6-dd49-4710-b449-b03303c7cf45@bootlin.com>
Date: Thu, 13 Nov 2025 12:11:08 +0100
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: Susheela Doddagoudar <susheelavin@...il.com>, netdev@...r.kernel.org,
 mkubecek@...e.cz, Hariprasad Kelam <hkelam@...vell.com>,
 Andrew Lunn <andrew@...n.ch>, Lee Trager <lee@...ger.us>,
 Alexander Duyck <alexanderduyck@...com>
Subject: Re: Ethtool: advance phy debug support

Hi,

On 13/11/2025 06:12, Susheela Doddagoudar wrote:
> Hi All/ Michal Kubecek,
> 
> To support Advanced PHY Debug operations like
> PRBS pattern tests,  EHM tests, TX_EQ settings, Various PHY loopback etc.....

Added a bunch of people in CC:

I don't have feedback on your current proposition, however people have
showed interest in what you mention, it may be a good idea to get everyone
in the loop.

For the Loopback you're mentionning, there's this effort here [1] that
Hariprasad is working on, it may be a good idea to sync the effort :)

[1] : https://lore.kernel.org/netdev/20251024044849.1098222-1-hkelam@marvell.com/

As for the PRBS, there was a discussion on this at the last Netdevconf,
see the slides and talk here [2], I've added Lee in CC but I don't
really know what's the state of that work.

[2] : https://netdevconf.info/0x19/sessions/talk/open-source-tooling-for-phy-management-and-testing.html

Maxime


> proposing a solution by custom ethtool extension implementation.
> 
> By enhancing below ethtool options
> 1.ethtool --phy-statistics
> 2.ethtool --set-phy-tunable
> 3.ethtool --get-phy-tunable
> 
> Currently standard ethtool supports 3 parameters configuration with phy-tunables
> that are defined in "include/uapi/linux/ethtool.h".
> --------
> enum phy_tunable_id {
>         ETHTOOL_PHY_ID_UNSPEC,
>         ETHTOOL_PHY_DOWNSHIFT,
>         ETHTOOL_PHY_FAST_LINK_DOWN,
>         ETHTOOL_PHY_EDPD,
>         /*
>          * Add your fresh new phy tunable attribute above and remember to update
>          * phy_tunable_strings[] in net/ethtool/common.c
>          */
>         __ETHTOOL_PHY_TUNABLE_COUNT,
> };
> 
> 
> Command example:
> # Enable PRBS31 transmit pattern
> ethtool --set-phy-tunable eth0 prbs on pattern 31
> 
> # Disable PRBS test
> ethtool --set-phy-tunable eth0 prbs off
> 
> 
> Let me know if the proposal is a feasible solution or any best
> alternative options available.
> 
> Thanks,
> Susheela
>