linux-kernel - Re: [PATCH net-next v2 1/5] ethtool: introduce core UAPI and driver API for PHY MSE diagnostics

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aKVSpmKR0MGZhAD1@pengutronix.de>
Date: Wed, 20 Aug 2025 06:44:22 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Andrew Lunn <andrew@...n.ch>
Cc: Jakub Kicinski <kuba@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>,
	Simon Horman <horms@...nel.org>,
	Donald Hunter <donald.hunter@...il.com>,
	Jonathan Corbet <corbet@....net>,
	Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	Kory Maincent <kory.maincent@...tlin.com>,
	Maxime Chevallier <maxime.chevallier@...tlin.com>,
	Nishanth Menon <nm@...com>, kernel@...gutronix.de,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	UNGLinuxDriver@...rochip.com, linux-doc@...r.kernel.org,
	Michal Kubecek <mkubecek@...e.cz>, Roan van Dijk <roan@...tonic.nl>
Subject: Re: [PATCH net-next v2 1/5] ethtool: introduce core UAPI and driver
 API for PHY MSE diagnostics

On Wed, Aug 20, 2025 at 05:03:14AM +0200, Andrew Lunn wrote:
> > Channel-to-pair mapping is normally straightforward, but in some cases
> > (e.g. 100BASE-TX with MDI-X resolution unknown) the mapping is ambiguous.
> > If hardware does not expose MDI-X status, the exact pair cannot be
> > determined. To avoid returning misleading per-channel data in this case,
> > a LINK selector is defined for aggregate MSE measurements.
> 
> This is the same with cable test. The API just labels the pairs using
> 
>         ETHTOOL_A_CABLE_PAIR_A,
>         ETHTOOL_A_CABLE_PAIR_B,
>         ETHTOOL_A_CABLE_PAIR_C,
>         ETHTOOL_A_CABLE_PAIR_D,
> 
> It does not take into account MDI-X or anything.

In the case of the cable test, MDI-X does not affect the reported
results, or if it does, we can actively change the configuration and
re-run the test. For SQI/MSE on this chip, however, the measurement is
purely passive. If the hardware does not expose an MDI-X indicator, we
cannot reliably assign the values to a specific pair, so we need the
LINK selector to avoid returning misleading data.

> > @@ -1174,6 +1246,60 @@ struct phy_driver {
> >  	/** @get_sqi_max: Get the maximum signal quality indication */
> >  	int (*get_sqi_max)(struct phy_device *dev);
> >  
> > +	/**
> > +	 * get_mse_config - Get configuration and scale of MSE measurement
> > +	 * @dev:    PHY device
> > +	 * @config: Output (filled on success)
> > +	 *
> > +	 * Fill @config with the PHY's MSE configuration for the current
> > +	 * link mode: scale limits (max_average_mse, max_peak_mse), update
> > +	 * interval (refresh_rate_ps), sample length (num_symbols) and the
> > +	 * capability bitmask (supported_caps).
> > +	 *
> > +	 * Implementations may defer configuration until hardware has
> > +	 * converged; in that case they should return -EAGAIN and allow the
> > +	 * caller to retry later.
> > +	 *
> > +	 * Return:
> > +	 *  * 0              - success, @config is valid
> > +	 *  * -EOPNOTSUPP    - MSE configuration not implemented by the PHY
> > +	 *		       or not supported in the current link mode
> > +	 *  * -ENETDOWN      - link is down and configuration is not
> > +	 *		       available in that state
> 
> This seems a bit odd. phylib knows the state of the link. If it is
> down, why would it even ask? 

Good point. I'll remove this part of comment.

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |